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1. if cre_init Atrn_ASM1 0 2 VERBOSE lt Ok abort If all localization resources have been allocated subsequent calls to cre init fail until a cre close is called to free resources Since all listeners share the same sound space the number of sources requested for each head should be consistent Important In the CRE implementation all gains were initially set by cre_init to GAIN_dB_OFF so that active analog inputs at full level will not pop on without user control The AuSIM implementation does not turn the gain off but rather initializes each source with no signal channel assignment To hear sound the programmer MUST assign a signal channel with cre define source cre select _source or cre_ctrl_wave Before connecting a signal channel the programmer may choose to make use of the cre _amplfy_source function to control the initial source amplitude Note The fixed point distance resolution within the RS 232 ATRON protocol is in hundreths of units If the base units are set to At rn INCHES then the smallest movement would be 0 01 GOLDSERVE Manual37 cre_update_audio Synopsis include cre_tron h int cre_update_audio void Description Synchronizes frames and controls signal processing This routine checks for any pending updates since the previous call recomputes signal processing parameters with respect to all affected source to listener relationships and passes the new
2. The atmospheric absorption distance can be accessed and adjusted or disabled from its default value with the cre define medium function Spreading loss roll off As sound waves radiate from a point source their power spreads over an ever increasing volume of propagation medium This spreading reduces the sound pressure level as the sound propagates from the source position to the listener position The effect of this spreading loss roll off is governed by an exponential curve which scales a sound s apparent power by the reciprocal of the sound s distance raised to an exponent In a perfect model this exponent is 1 0 but anechoic simulations may need some adjustment to sound right The exponential factor for all sources may be examined and adjusted from its default value through the cre define medium function 32 GOLDSERVE Manual Chapter 4 CRE TRON API Function Reference Data stuctures wavFt The waveform structure and typedef are provided for the application developer to have detailed information on open wave forms for the purpose of computing useful estimates such length of play All members are read only except wavEt next typedef struct wavFs const char fname host soundfile filename void pSignal pointer to the signal buffers struct wavFs next linked list pointer for user void synch synchronize with this signal int diskBased TRUE if file still open
3. displays the sound space by updating the hardware The cre_init call will locate and initialize sufficient hardware to localize two sources locate the listener s head at the origin and locate a sound source 50 inches directly in front of the head by default Since a zero was specified for the units argument locations will be interpreted in inches the default units The HeadLoc variable therefore refers to a position 10 inches below the origin The source is by default a uniform radiator After successful initialization the call cre amplfy source turns source 0 on Note that all sources are initialized with no amplification In order to hear anything from a source after initialization cre amplfy source must be used The cre open wave and cre ctrl1_wave calls are used to load a waveform from disk and play it The listener is located once to move from the default position to the one specified by HeadLoc Then the program moves the location of source 0 using cre_locate_source and uses cre update audio to flush all changes to the hardware in order to display the new sound space for the listener until any character is typed at which point the hardware is closed 26 GOLDSERVE Manual Coordinate system The environment in which localized sounds can be experienced is described by a three dimensional coordinate system Within this coordinate system six dimensional vectors are used to specify the position an
4. include cre_tron h struct float azim elev rang polar int cre_get_polar int head int src float polar Retrieves the relative position in polar coordinates of sound source src with respect to listener head If the sound source was relatively positioned either the rendering system is imaging reflections or the rendering model is far field The information should have been computed in the most recent update but if not it will be computed from global coordinates The retrieved polar coordinates are written to the polar structure head the identifier of an initialized listener from which the source is relatively located The macro ALL_HEADS is not supported src the zero based index of the audio source to which the bearing is requested The macro ALL_SOURCES is not applicable polar a pointer to storage for three floats Upon success three floats will be copied into the storage pointed to by polar azimuth elevation in radians and range in current units On success Ok On failure Error0 audio source srcis out of range Errorl polaris NULL Error2 uninitialized listener identifier head struct float azim elev rang polar cre_get_polar 0 src amp polar 80 GOLDSERVE Manual Remarks 3 function is provided for utility only GOLDSERVE Manual81 cre_test atron Synopsis include atron h int cre test_atron int verbose Description Tests the connection to the localization serv
5. Figure6 Six dimensional coordinate system with listener located at 0 0 0 0 0 0 Head tracking Closed loop tracking of head position can provide an important enhancement to real time audio localization The proprio sensation correlation in the human brain between head movement and aural differences is very tight Slight incongruities can cause simulated aural images to collapse Head tracking allows AuSIM s dynamic audio localization to maintain a consistent source to listener relationship providing motion parallax localization cues The Software applications using AuSIM3D libraries work well with many six degree of freedom tracking systems including e Fakespace Labs BOOM integrated mechanical tracker and head coupled stereo visual display or popular electromagnetic devices such as 28 GOLDSERVE Manual e Polhemus Navigation s Isotrak Fastrak InsideTRAK and 3SPACE tracker and e Ascension Technology s Flock of Birds multiple receiver system or popular ultrasonic devices such as e Logitech s 6D head tracker from Fakespace Labs or popular inertial hybrid devices such as e InterSense Technology s 15 300 15 600 IS 900 and the source less InterTrax There is no direct software support for tracking devices in The AuSIM3D client libraries do not directly support these tracking devices however the vectors resulting from head tracker sensor sampling are perfectly compatible with AuSIM3
6. PROTEUS_RESET to reset the Proteus synthesizer to boot up condition PROTEUS_I NTERNAL to select internal MIDI string input In this mode the received TRON MIDI messages are PROTEUS EXTERNAL to select external MIDI string input In this mode the through it synthesizer only receives messages s external port and ignores messages passed by TRON MIDI functions PROTEUS_L OAD_PRESET_FILE to map a preset file specified by the NULL terminated character string filename pointed to by data 74 GOLDSERVE Manual Returns Error3 if the preset file does not exist or is invalid or if the load fails data optional Set to NULL except when used with PROTEUS_LOAD_PRESET_FILE where it is set to a null terminated character string Retum Value On success Ok On failure Error0 audio source src is out of range or no Tron sources have been initialized Errorl invalid command cmd Error2 command cmd requires data but data is NULL Error3 command specific error See descriptions above Example cre _set_midi 2 PROTEUS_RESET NULL GOLDSERVE Manual75 cre_msg_midi Synopsis Description include cre_midi h int cre_msg_midi int src int msg int chnl int datal int data2 Constructs and sends a MIDI channel voice message to the proper Proteus synthesizer channel or MIDI port associated with s
7. defined in ATRON H Supported drivers are Atrn_CMP1 D ct P n_BMP1 trn_BMP3 trn_BMP4 trn_ASM1 gt TP P DP trn_A441 Note Using any outdated driver values will cause cre init to fail GOLDSERVE Manual35 36 Head Sources Mode GOLDSERVE Manual listener identifier to be initialized An identifier must be unique for each listener numbered sequentially from 0 to 63 If the listener is also a sound source to other listeners the _ORATOR_ flag may be OR ed with the listener ID The _ORATOR_ flag forces the source with the same ID as the given listener ID not to be mixed for that listener If the listener identifier has been previously initialized the requested sources are additional maximum number of sources to be heard by the given listener bit field OR ed from ATRON H macros and enums units defined in the ATRNunitsDef enum Select one from trnINCHES trn FEET A A AtrnMMETER A trnCMETER Atrn_ METER mode flags _VERBOSE_ set verbose messages to be displayed Retum Value Example Remarks On success returns the number of sources allocated On failure Erroro0 no sources requested no hardware available or Trons already initialized Error1 memory allocation error or load failure Error3 acoustic headmap invalid or load failure Error4 invalid driver type Error5 invalid listener identifier Error server response error
8. double sampleRate in Hz assumes 44 1kHz short numChannels 1 mono 2 stereo sampleSize in bytes 1 8 bit 2 16 bit frameSize in bytes samplesize channels waveld remote serial identifier sourceld value 1 if not attached float pitchFactor pitch shift factor unsigned long numFrames total frames in file remFrames remaining frames NOT loaded selFrames length of signal selection startFrame beginning of signal selection unsigned long loopStart loop start in samples loopEnd loop end in samples loopCount loop count wavFt GOLDSERVE Manual33 MEMBERS fname pSignal next synch diskBased sampleRate numChannels sampleSize frameSize waveld sourceld pitchFactor numFrames remFrames loopStart loopEnd loopCount host sound filename string with full path pointer to waveform signal data internal use only pointer to next waveform struct for application use pointer to waveform that this wave will synchronize with Boolean non zero indicates that file is open sample rate of the sound signal in samples per second number of signal channels 1 monoaural 2 stereo Currently only supports monoaural bytes per sample 1 8 bit 2 16 bit Promotes 8 bit RIFF files to 16 bit playback Non RIFF files are assumed 16 bit bytes per frame frame sampleSize numChannels unique index assigned for remote c
9. following categories e General system functions declared in CRE_TRON H cre_init driver head sources mode Gre update audio cre_close driver head cre_end O cre detect prm e Listener head functions declared in CRE_TRON H cre define head id prm pts data cre locate_head id hloc e Audio source functions declared in CRE_TRON H cre define source id prm pts datal cre _locate_source id sloc cre_amplfy source id dB cre _select_source id channel GOLDSERVE Manual23 cre _pmeter_source id amp power e Propagation medium specific functions declared in CRE_TRON H cre_define_medium volm prm pts datal e Waveform functions declared in CRE_WAVE H cre_open_wave wavefile mode cre_ctrl_wave src wave cmd data cre_close_wave wave e MIDI functions declared in CRE_MIDI H cre send midi src midistr cre_set_midi src cmd data cre _msg_midi src msg chnl datal data2 e Acoustic research functions declared in CRE_TRON H cre_set_rel pos head src azim elev gain cre_get_polar head src polar e Acoustetron test function declared in ATRON H cre_test_atron verbose Sample rates and driver selection The GoldServe can run multiple software drivers Each driver implements the CRE_TRON software interface but might offer different functionality see the description of cre_init for specific driver details One of the important distinctio
10. in an application using the cre open wave and cre ctrl wave commands If you wish to play the same sound file simultaneously on multiple sources you must open that sound file multiple times as well The maximum length of a sound file is limited only by the size of the hard disk since files get automatically played back from disk when playback memory is exhausted If you hear stuttering gaps in the wave file playback the system bandwidth has reached its limit and too many files are being started at the same time If a sound file s name ends with WAV it must be formatted as a RIFF file format per Microsoft Multimedia specifications WAVE files can be created on the server using the Wave File Editing option available for the GoldServe or using other sound recording and editing tools and downloading the sounds from the client If a sound file s extension is not given the WAV is assumed and appended If a sound file s extension is explicitly something other than WAV the content must be in the CD Audio format 16 bit PCM words at 44100Hz 30 GOLDSERVE Manual Extemal inputs The GoldServe can localize concurrent live sounds that are connected via analog or digital inputs The external inputs can take their data from microphones CD players or other sources of analog audio The physical connectors depend on the GoldServe system see your system specific guide For all drivers GOLDSERV
11. mostly far field never comes near the receiver you can optimize the dynamic range by setting the gain to a higher value A table relating source amplitude setting to clipping distance may be found in ATRON H If you need to adjust the relative amplitude of the source it should be done at the synthesis of the sound cre amplfy source will provide such relative amplitude service but you run the risk of ruining the 3D effect for near field sounds GOLDSERVE Manual59 cre_select source Synopsis Description Parameters Retum Value Example include cre_tron h int cre_select_source int id int channel Selects from among the available hardware analog input channels for a given source id for all listeners The implementation of this function is hardware specific and the command may not be desirable globally This function is not defined for all drivers such as At rn_CMP1 which uses all inputs available This function may produce unexpected results when used with different drivers rendering the same audio source to different listeners This has the same effect as cre define source id AtrnCHNLinput 1 channel id the zero based index of the audio source to be patched The macro ALL_SOURCES is supported Channel the zero based index of the analog input channel on the target hardware On success Ok On failure Erroro audio source idis out of range or no Tron sources have been initialized Errorl1
12. tee Zeeche 48 cre define SOUICE iia ld evap ces 50 cre locate SOUTO caracas tampa 55 cre amplty ROU curiosa Eege 58 cre select SOUEEN 60 Gre PME EE SOU iii 61 cr define medi iii ds 62 CLES OPEN WAVE data 65 CLE CH WAVE ciu tir did ds 67 crecio WI iia 72 ce send Midi ii ia dias elsa 73 2 GOLDSERVE Manual CL OL SOL IMIG ER heehee A eae 74 TEM EE 76 cre set rel POs cia idas 78 LE Bet POLAT ninia aa 80 A A A 82 Appendix 1 WEE Te OS 83 FCE NOTICE coi tota 90 Appendix 2 NOA 91 GOLDSERVE Manual 3 Chapter1 Introduction Overview Interactive real time auditory localization greatly enhances the effectiveness of virtual environments By presenting sounds to a listener as located in three dimensional space an application transmits more information to the user stimulating situational awareness and creating a sense of immersion in a virtual environment The audio simulation technology AuSIM3D from AuSIM Inc uses physical modeling and empirical data to synthesize a sound space in a completely natural and realistic way When listening to a system incorporating such technology a user not only feels immersed by real world three dimensional sounds but also can use natural filtering to discern and comprehend any of several layered concurrent sound streams The GoldServe audio localizing systems from AuSIM Inc incorporate AuSIM3D technology and perform real time localization of multiple real time audi
13. to be loaded If pts 0 datais ignored and the default HRTF map is reloaded Otherwise the filename pointed to by data is loaded from the directory given by the HRTF environment variable The pts value should be the string length of the filename for consistency AtrnDELAYtable Redefine the interaural delay table This parameter requires a properly formatted interaural delay table This parameter is provided for psychoacoustic research and is otherwise undocumented AtrnDELAYscale Scale the current delay table When pts 1 this will scale all interaural delays by the float value pointed to by data If pts 0 datais ignored and the interaural delays are reset to their GOLDSERVE Manual45 default values AtrnHRTFresolve Sets the filter order trim AtrnHRTFmodel Sets the model to use This will be one of NearField FarField or MixedField AtrnHEADgain AtrnHEADgain sets a single floating point dB level for the final conversion gain in preparing a listener s signal pair for output The pts parameter is ignored AtrnDISPLAYtype AtrnDISPLAYtype sets the output type for filtering per display device The enum describing the particular device is given in the pts parameter Choose one of the following eqGenericHeadphone eqGenericNearphone eqSennheiserHD250 or eqSennheiserHD570 data is ignored AtrnEQleft Downloads the display type for left EQ coefficients AtrnEQright Downloads the displ
14. tumbler on the screen What to Do Either your server environment variables PC startup files config sys and autoexec bat or DSP card address switches have been changed A call to the factory phone number on front cover is your best bet Problem Your local demo program does not produce sound but there is a tumbler What to Do The server is up and running and very likely producing sound The problem must be in the audio connection between the server and your ears Check all connectors and make sure the headphone amp is powered on Problem The server runs in local demo mode but does not respond to the client What to Do The communication link is most likely the problem 14 GOLDSERVE Manual Serial communication link Make sure both ends are operating at the same baud see chapters on Startup menus and Environment variables for details On WinNT systems the client and server baud should both be set to 115200 The server is so set at the factory but the client may be set by setting the environment variable TRONCOM by adding the following line in the client s AUTOEXEC BAT file set TRONCOM 1 1152 30 GOLDSERVE Manuall5 Client software and directory organization Directory File Description Client Cli EE Test client application Cre_test exe Test client application Demo exe Demonstration program Example exe Ltrkstrm exe A very simple example program Test tracker application Ltrkstrm exe Test tracker
15. x forward and z up a positive pitch is down AtrnROL angle of n to n from the world y axis about the world x axis of the head s y axis From the listener s point of view a clockwise roll of the head rolls y into z and is 48 GOLDSERVE Manual Retum Value Example therefore positive On success Ok On failure Error0 no Trons have been initialized Errorl headLocis NULL Error2 uninitialized listener identifier id const float headLoc 6 10 0 20 0 30 0 0 0 0 0 0 0 cre _locate_head 2 headLoc GOLDSERVE Manual49 cre_define_source Synopsis include cre_tron h int cre_define_source int id int prm data Description Allows the user to specify paramete int pts const void rs defining the source rendering model directional radiation pattern localization ON OFF and listener linkage The function is a generic dispatcher that may be extended in future releases See parameter descriptions below for specific behavior Parameters the zero based index of The macro ALL_SOURCI id the audio source in reference prm ATRNsrcDef enumerat following values AtrnRADfields trnRADprofile trnPROFILEpts trnSPATIALOff trnSPATIALon trnHEAD1 ink trnHEADunl ink trnGAINdist trnCHNLinput A A A A A A A A A AtrnCHNLmidi A trnDPLRfactor 50 GOLDSERVE Manual ES is supported one of the pre defined parameter values from the ion This can be o
16. D and the CRE_TRON APL There are many ways to get head tracker support 1 All trackers bought through AuSIM Inc are value added with AuSIM s AuTrak C tracker class library for Win32 AuTrak provides a single API for all types of trackers as listed above AuTrak may also be purchased separately 2 Many simulation toolkits EAI Sense8 s WorldToolKit Division s dVise Paradigm Multigen s Vega Centric s EasyScene etc include support for these tracking devices and others 3 Write your own Most of these tracking instruments are RS 232 serial devices for which many operating systems provide good programming tools Some of the vendors of these instruments provide sample code 4 Use the AuSIM3D service application GoldServ running on the GoldServe DAPU with its built in tracking support to directly read your head tracking instrument and automatically update your listener s position For the AuTrak toolkit or build your own methods see the respective associated documentation For the GoldServ service application usage see Appendix A GOLDSERVE Manual29 Audio sources Sound files Each GoldServe can playback and localize multiple concurrent monophonic sound files In order to play multiple sound files simultaneously each sound file must be assigned to a different localization source Before a sound file can be played it has to be loaded onto the GoldServe Once a wave file is loaded it can then be used
17. DRIVERS ALL HEADS will close all audio and wave files cre_close is required to safely terminate a host application driver selected from enumeration list in ATRON H see ere init The macro ALL DRIVERS shuts down all CRE drivers head the identifier of an initialized listener to be closed The macro ALL_HEADS will force all listeners associated with the given driver to be closed On success Ok On failure Exrroro no Tron sources have been initialized Error1 invalid driver type Error2 uninitialized listener identifier head cre close ALL DRIVERS ALL HEADS GOLDSERVE Manual39 cre_end Synopsis include cre_tron h void cre end void Description This is an alias for cre_close ALL DRIVERS ALL HEADS and is compatible with the ANSI C atexit function Parameters None Retum Value None Example atexit cre end 40 GOLDSERVE Manual cre_detect Synopsis Description Parameters Retum Value Example include cre_tron h int cre_detect int prm This is an undocumented CRE function that has been formalized and extended in the AuSIM implementation to retrieve system parameter values of interest to the application programmer prm one of the pre defined parameter values from ATRNdetectDef enum Values can be one of the following list AtrnLSTNRinit AtrnASRCinit AtrnFRAMErate AtrnSYSunits AtrnWAVBUFavail On success non negative value detected On
18. E Manual31 Special topics Directional radiators For different audio sources and environments the sound will travel through the atmosphere in the space in different ways The directional radiators are used to model this propagation pattern The following figure shows two different radiation patterns for two different directional sources The heavy lines indicate contours of constant pressure As you can see in front of the speaker the sound attenuates much more slowly with distance than behind the speaker where almost no sound propagates If there were objects placed in the environment you would see a change in the radiation pattern when the sound is absorbed and reflected from the surfaces of the object Atmospheric absorption The GoldServe includes an atmospheric absorption model which attenuates higher frequencies a greater amount than lower frequencies The degree of attenuation depends on the distance through which the sound travels in the atmosphere the further it travels the greater the relative attenuation As a result distant sounds have a lowpass filtered or muffled characteristic This model is controlled by a distance parameter For sounds that are close to the listener as compared with the absorption distance the relative high frequency attenuation will be slight Conversely sounds whose range is equal to or greater than this distance will incur correspondingly more high frequency attenuation
19. ERVE Manual e sweet spot the location where a listener has to be placed to get the optimal effect when listening to a specific speaker setup e transmission loss sounds get absorbed as they travel through objects such as walls similar to atmospheric absorption in the case of traveling through a medium Transmission loss models are needed to realistically simulate sounds outside a window or in the next room update rate the number of times that a specific instance of a sound space is re computed and updated per second Each time any object moves most often the listener the space needs to be updated The higher the update rate the faster objects can move without creating audio artifacts such as clicking Audio update rates generally range from a minimum of 20Hz to 100Hz Video update rates are usually in the same range TV signals are updated at 30Hz e wave file a digital sound file stored in the Microsoft RIFF file format e wavetracing the idea of tracing sound waves as they emit from a source and bounce around an environment walls objects openings The resulting sound reflections are rendered to a listener to create a more convincing 3D effect as well as a more immersive familiar and realistic sound space GOLDSERVE Manual89 FCC Notice WARNING This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with this instruction manual may cause interferen
20. GoldServe AuSIM3D Gold Series Audio Localizing Server System Users Guide and Reference Covering both Hardware and Software AuS M Inc Manual Revision 1d October 2001 Copyright 2001 AuSIM Inc All rights reserved AuSIM Inc acknowledges all trademarks found in this manual AuSIM Inc 4692 El Camino Real Suite 101 Los Altos CA 94022 Phone 650 322 8746 FAX 561 325 0849 e mail info audiosimulation com web http www ausim inc com Contents Chapter 1 Chapter 2 Chapter 3 Introduction siose onee e aran E Er E r isi O gedeien GoldServe System Components mcccoccccccnonononncncnononononon cono nonnnnos Configurations in an AT E E tb Organization of this manual o ooccccicicncnonnnnnnnnncnonnnononononananano coro rncncncnos Audio localization wiv i sssisciseesiesdasestscussnsssionsvesostvonsdasebisectetbeoncecuaststventie Localization inputs amp outputs m cccccicccinnonononcnnnnnncnnononononocncncn conos Real time signal input Sampled playback input Displays for localized sound Localized output Getting Started AAA ZGeegdeeEedeES ege deed Sesa ere Required red Hard Ware ii cissisinssateviscdesivies See EENS EES SOW ALE estate EEN Input and output ampht fiers Output vi ii isis Headphones sicarios copias desisti Nearphones isis tana an iban Quad pekt Eed et e ee Eeer Multimedia stereo speakers 00 ci eeccesseseeseeeceerseseseeteesenseeeaees Other stereo speakers iei i pisn Sys
21. GoldServe s disk returning a pointer to the allocated wavefile structure wavFt Sound file control such as playback through a particular source is effected through cre ctrl wave Currently the only formally recognized sound file format is RIFF MS Windows WAV format Note that independent of which driver is being used both 22 05 kHz and 44 1 kHz wave files can be opened and played back Note All calls to cre_open_wave should precede any call to cere init and every ore open wave should be paired with a corresponding cre close wave Wave file open close pairs are independent of but must enclose cre init cre_close pairs The maximum number of concurrently open wave files is determined by the amount of system memory available see remarks below Wavefile a string which specifies the filename to be loaded from disk If the filename extension is WAV the file must have a valid RIFF format header mode This parameter is no longer needed and is ignored On success wavFt the returned structure will be empty See cre ctrl wave s wave WaveCTRL FSTAT NULL command to filled the wavFt structure On failure NULL filename wavefile not found could not be opened was invalid or system out of memory char fname test wav wavFt wave cre open wave fname NULL GOLDSERVE Manual65 Remarks if wave NULL printf Ss failed to open n fname All wave files are loaded into memory The maxi
22. Hotter signals up to 4 dBu can be accommodated via factory adjustment A second Addabox may be added to the GoldServe Sampled playback input Any sampled signal stored as PCM data hereafter generically called wavefiles may be replayed by the GoldServe system as a source input All wavefiles are converted to 32 bit floating point and resampled to the simulation sample rate at load time Unlike legacy CRE audio simulation products the GoldServe system loads all wavefiles entirely into memory upon opening performing preprocessing as necessary This mechanism enables the GoldServe to accommodate wavefiles opened from a variety of locations including hard disk CD ROM or mounted network drive GoldServe does not currently support CD A Internet URL s or compressed formats such as MP3 Displays for localized sound The key to localizing sounds for a particular listener is to compute the signal shapes as they should be entering the listener s respective ear canals and then deliver them to the canal entrance A pair of signals intended for delivery at the ear canal entrance whether computed or measured is called binaural To contrast stereo signals are intended for loudspeaker display utilizing the listening environment for the final propagation to the listener If the characteristics of the listening environ ment are well known essentially the transfer function from the loudspeakers to the listener then compensation cou
23. I commands midistr terminated by MIDI_MsgTerm as defined in CRE_MIDI H to the MIDI port on the Tron card that is responsible for source src A well constructed MIDI string is assumed See CRE_MIDI H for some pre defined MIDI strings Parameters src the zero based index of the audio source in reference The macro ALL_SOURCES is supported same message is sent once to each port i e per pair of sources midistr a character string of any length of MIDI commands terminated by MIDI_MsgTerm Retum Value On success Ok On failure Error0 audio source src is out of range or no Tron sources have been initialized Errorl1 MIDI string midistr is invalid Example MIDIbyte MyFavoriteNote 10x90 Ox3C 0x40 MIDI_MsgTerm cre_send_midi 1l MyFavoriteNote The message terminator MIDI_MsgTerm is not sent to the port GOLDSERVE Manual73 cre_set midi be extended in future releases See Synopsis include cre_midi h int cre_set_midi int src int cmd void data Description Provides necessary services for the Proteus synthesizer on a Beachtron card which is associated with source src The function is a generic dispatcher that may command descriptions below for specific behavior Parameters src the zero based index of the audio source in reference The macro ALL_SOURCES is supported In this mode the TRON MIDI messages are received cmd an integer which specifies one of four Proteus commands
24. Loc 6 d Ee 007 TOS Me 02 0 DO Hr ds wavFt wave initialize two Tron sources with verbose report if cre_init Atrn_ASM1 HeadID Sources _CONSOLE_ _VERBOSE_ lt Ok return open WAV file and load wave form using all buffers if wave cre_open_wave WaveFile 0 printf nwave load error return play open wave form as SourceID with repeat loop cre_ctrl_wave SourceID wave WaveCTRL_LOOP NULL locate listener once not moving GOLDSERVE Manual25 cre_locate_head HeadID HeadLoc printf nPress Any Key to Exit enter simulation loop until key is pressed while kbhit SrcLoc AtrnY step move source location if SrcLoc AtrnY lt PanLimit SrcLoc AtrnY gt PanLimit step step reverse panning direction set new location as location of source 0 in space cre_locate_source SourcelD SrcLoc cre_update_audio flush all changes stop wave form playback and detach from SourcelD cre_ctrl_wave SourceID wave WaveCTRL_STOP NULL cre_close_wave wave close waveform cre_close Atrn_CLOS HeadID close Tron printf An The example program listed above is a minimal program which initializes the GoldServe loads and plays a wave file turns on a single source to be used positions a listener in space moves a source between two points in space and
25. ance between ear canal openings AtrnAURALcrown AURAL OFFSET along Z axis Typically either the vertical separation of ocular and aural axes or the vertical offset to the head tracking sensor which is often placed on top of the head An offset from the head crown which is above the aural axis would be negative The single value AURAL OFFSET parameter settings must have either a positive value pts 1 and one float pointed to by data to set a new value or pts 0 to reset the default value in current units data will be ignored These parameters locate the pinnae with respect to the head location given in each call to cre locate head along the right handed head coordinate axes of which the positive X axis extends out in front of the listener The values must be in the current units as set by cre init Setting to At rnAURALpinnae affects only the spatial relationship of sound sources and receivers and not the temporal delays See AtrnINTERAURAL below for temporal control The head location to the head center vector direction determines the sign of the AtrnAURALocular and At rnAURALcrown offsets Negative values for At rnAURALpinnae may yield unpredictable results Default offsets are zero except for At rnAURALpinnae which is one half the interaural separation in current units specific to the loaded listener map AtrnAURALoffsets The set of ordered AURAL OFFSETs With a single call to cre define head this parame
26. application Win32com Communications test program cre_tron h all CRE header files include atron h lient lib Source code main library for serial server Mstrak32 1ib Source code main library for tracker code RETRON_Ref txt CRE TRON reference manual GoldServe pdf wavelist html This document Catalog of available wave files BasicCRI connect WIN32CO WIN32CO demo Example code and project workspace QA Example code and project workspace test wav welcome wav quack wav jaws wav Sound files Figure 4 Client directory organization WinNT Win9x client 16 GOLDSERVE Manual _ File Description listAtron Utility to list wave file directory on Atron II downloadAtron Utility to download wave file to Atron II deleteAtron Utility to delete wave file from Atron II playAtron Utility to playback a wave file on Atron II audioClient An X windows based sample application example A very simple example program demo Demonstration program F cre_tron h all CRE header files include atron h z re_api c Source code switching API cre_client c Source code main library for serial server cre_serial_io C Source code serial driver aio_client c Source code main library for ethernet server libCRE a Object library Makefile Makefile to build libCRE a Makefile Makefile to build test programs demo c Source code for test programs stresstest c Test dk Makefile Makefile to build utility prog
27. as the signals that someone perceives when listening to a sound that is coming from a location in real life 3D space HRTFs are the core concept behind AuSIM3D since they contain the information that is necessary to simulate a realistic sound space see localization Once the HRTF of a generic person is captured it can be used to create AuSIM3D sound for a large percentage of the population most people s heads and ears and therefore their HRTFs are similar enough for the filters to be interchangeable IID Interaural Intensity Difference see 3D sound ITD Interaural Time Difference see 3D sound e listener an object in a sound space that is sampling listening to sound usually a head with associated HRTF characteristics materials by absorbing sound energy at different frequencies the material of which an object is made effects the way the sound reflects off and transmits through the object A carpeted room sounds very different from a glass room An object s material characteristics can be measured empirically by recording known sounds as they bounce off materials e medium see atmospheric absorption and transmission loss e MIDI MIDI or Musical Instrument Digital Interface is a standard control language that is used for communication between electronic music and effects devices mono monophonic refers to a single audio signal usually rendered on a single speaker Mono sounds appea
28. ay type for right EQ coefficients 46 GOLDSERVE Manual Retum Value On success Ok On failure Error0 no Trons have been initialized Errorl invalid parameter prm Error2 pts gt 0 but datais NULL Error3 AHM is invalid or load failure Error4 uninitialized listener identifier id Example setting offset for a tracking device on top of the head const float offsets 3 0 0 INTERAURAL CROWN_OFFSET cre define head 2 AtrnAURALoffsets 3 offsets GOLDSERVE Manual47 cre_locate_head Synopsis Description Parameters include cre_tron h int cre_locate_head int id const float headLoc Locates the head of a listener six dimensionally in world coordinates It only updates changes from previous state recalculating pinnae locations as needed This function does not affect processing until a synchronization call to cre_update_audio is successful id the identifier of a listener to be defined HeadLoc a pointer to an ordered array of six floats as follows AtrnX world x axis coordinate AtrnY world y axis coordinate AtrnZ world z axis coordinate AtrnYAW angle of n to n from the world x axis about the world z axis of the projection of the head s x axis onto the world x y plane Looking down at the x y plane a counter clockwise rotation is positive AtrnPTC angle of 11 2 to 11 2 from the world x y plane of the head s x axis about the world y axis Remember that with
29. ce is 1 96 inches from the head if units of inches default are being used To alter this distance scale the base 2 by the macro GAIN_RATIO Distant sound sources may need to be set much higher as much as 30 dB in order to be audible at the listener s position id the zero based index of the sound source to be amplified The macro ALL_SOURCES is supported dB the amplification level in decibels The macro GAIN_dB_OFF is provided to definitively turn off a sound source Any value less than 120 dB is interpreted as off On success Ok On failure Erroro audio source id is out of range or no Tron sources have been initialized Errorl1 dB is unreasonable To prevent floating point overflows dB should not exceed 20 EXPONENT LIMIT defined in ATRON H cre_amplfy source ALL_SOURCES 1 0 This is the most misunderstood function in the CRE_TRON API Attenuation over distance is a very important 3D cue over which the system must have dynamic range to apply As a sound source gets closer to a receiver its sound pressure level must increase exponentially nominally 6 dB for every half of the distance but there is a maximum volume that audio hardware can and for 58 GOLDSERVE Manual safety reasons should reach We have set the library so that the maximum volume is reached for a 0 dB at 2 5 inches from the receiver If a source is within this range our software can provide very little distance cue If the source is
30. ce to radio communications It has been tested and found to comply with the limits of a class A computing device pursuant to Subpart J of Part 15 of FCC rules which are designed to provide reasonable protection against such interference when operated in a commercial environment Operation of this equipment in a residential area is likely to cause interference in which case the user at her own expense will be required to take whatever measures necessary to correct the interference 90 GOLDSERVE Manual Appendix 2 Errata Chapter 1 Real time signal input Real time signal input is not yet supported at this time However it is at the top of the list of functionality to be completed and it is expected to be available within a matter of days Chapter 2 Software Although the sample UNIX GUI application audioClient in theory should work as described it has not yet actually been tested by AuSIM with the current line of GoldServe servers Therefore the reliability of this application should be considered less solid than other applications this document mentions Chapter 2 System components and specifications System library and demos not yet available on CD GoldServe User Manual this document available only online not in hardcopy e Chapter 2 Hardware Step 3 The double beep when the server is initialized has not yet been activated Step 5 and Startup problems Audio service through ethernet is not supported at this time Howeve
31. ction principal direction of aural emission of a sound source e Chapin William the founder of AuSIM Inc and inventor of the Crystal River Engineering Acoustetron WaveTracing and AuSIM3D GoldServe Audio Localization Server Often confused with Harry Chapin his distant cousin and legendary performing artist Harry is deceased e Convolvotron the world s first multi source real time digital localization system built by Crystal River Engineering for NASA in 1987 e direct path the direct path from a sound source to a listener s ears as opposed to the path that includes reflections off surfaces The direct path allows a listener to tell where each sound is coming from 360 degrees both in azimuth and elevation This is the main concept of any 3D sound system Doppler effect the change in frequency of a sound wave due to the relative motion between a sound source and listener For example when a car moves past you while sounding its horn you will hear a drop in pitch as the car passes e extended stereo a term that summarizes a number of techniques that involve processing of traditional stereo sounds with the goal of making them appear to originate from a range which extends beyond the physical speaker locations The effect is often limited to a planar arc in front of the listener with everything at the same elevation Extended stereo effects tend to be incompatible with headphone listening and to only have the intended effect if
32. d orientation of the listener s head and of all sound sources The inputs to the GoldServe external or wave forms are mapped to the corresponding locations in the coordinate system relative to the listener s location The GoldServe software library represents a six dimensional location vector as an array of six floats 32 bit floating point number In this array the first three elements specify the x y and z position in space in number of units units are selected at initialization of the GoldServe see cre_init The second three vector elements specify the yaw pitch and roll in radians They define the orientation of the source or head at position x y z The coordinate system is adopted from the vehicle dynamic simulation world As illustrated in Figure 4 the system is right handed with the positive x axis straight ahead and the positive z axis ascending vertically Orientations are specified as right handed radian Euler rotations roll pitch and yaw about respective x y and z axes The six element vector employed in the GoldServe software in using cre locate head andcre locate source is ordered lt x y Z yaw pitch roll gt The order of rotations depends upon the rotation basis With respect to the global coordinate system from a local coordinate system that initially coincides with the global one an object is rolled pitched yawed and finally translated GOLDSERVE Manual27 Z
33. d the identifier of an initialized listener from which the source is relatively located The macro ALL_HEADS is supported src the zero based index of the audio source to be amplified The macro ALL_SOURCES is not supported To locate multiple audio sources this function must be applied for each sound source azim counter clockwise rotation in radians from straight ahead of the source s projection onto the head s median plane elev angular elevation in radians from the head s median plane to the source Note that as opposed to pitch an elevation is positive above the plane and negative below it gain linear amplitude from 0 0 to 1 0 for the mixed field and far field models No range is computed hence acoustic rendering effects such as reflected source 78 GOLDSERVE Manual Retum Value Example On success On failure images Doppler pitch shift and atmospheric absorption will be interpreted as though the source were located at the head s center For near field models gain is interpreted as a range greater than 1 0 in current units with the rendering effects including gain computed normally Ok Erroro audio source src is out of range Errorl gain argument out of range for current rendering model Error2 uninitialized listener identifier head cre_set_rel_pos 0 src 0 0 0 0 1 0 GOLDSERVE Manual79 cre_get polar Synopsis Description Parameters Retum Value Example
34. dServe use headphones with as few metal parts as possible in order to avoid electro magnetic interference between headphones and tracking sensors Try to avoid tracking systems that use transmission frequencies between 20 20 000 Hz the audible region Nearphones In applications where unobtrusive equipment is important nearphones can be used instead of headphones Nearphones are two speakers left and right signal placed near within 25 inches the user s ear An example of where nearphones are applicable would be a simulator cab with a projection screen and two speakers mounted next to the user s seat The user can get in and out of the cab by simply sitting down in a chair To achieve optimal results the user s head should not move out of the range of the speakers or turn more than 45 degrees in any direction The closer the speakers are placed to the user s ears the better the resulting localization perception Quad speakers If speakers cannot be placed close to the listener a quad speaker setup left front back and right front back is recommended In this case the left output of the GoldServe would be wired to both left speakers the right output to both right speakers The listener should be placed near the center of the square formed by the four speakers Multimedia stereo speakers The term multimedia speakers refers to a stereo speaker setup where the speakers are built into a computer monitor or are located clo
35. different levels of localization performance Their ranking in order from best to worst headphones nearphones quad speakers multimedia stereo speakers and other stereo speakers Headphones Headphones are an important part of a virtual acoustic system Your GoldServe system has been optimized for use with circumaural diffuse field equalized headphones i e headphones which enclose your entire ear as opposed to headphones that are placed inside the ear canals For optimal localization results we strongly recommend usage of high quality headphones The reference headphones for use with AuSIM HRTF models are Sennheiser HD250 I s contact AuSIM for availability Depending on your virtual audio application the difference between acoustically open or acoustically closed headphones might be important Open headphones such as the Sennheiser HD540 II s do not provide a tight seal between the ear and the environment Such headphones are useful in applications where the user has to be able to hear sounds from the surrounding environment operator s voice warning signals during the simulation Acoustically closed headphones try to suppress all sounds other than the ones delivered by the headphones They are useful in completely immersive virtual environments or to attenuate noisy surroundings trade shows noisy workspaces 10 GOLDSERVE Manual If you plan to use electro magnetic head tracking devices in conjunction with your Gol
36. dio source src is out of range or no Tron sources have been initialized Errorl1 waveform structure pointed to by wave is invalid Error2 command cmd is unsupported Error3 wave already playing on another source Error4 failed attempt to perform Example wavFt wavep cre_open_wave TEST WAV 4 cre_ctrl_wave 0 wavep WaveCTRL_LOOP NULL do other things while sound plays cre_update_audio tend to playback buffers do other things while sound plays cre_ctrl_wave 0 wavep WaveCTRL_STOP NULL cre_close_wave wavep GOLDSERVE Manual71 cre_close_wave Synopsis Description Parameters Retum Value Example tinclude cre_wave h int cre close wave wavFt wave Closes the wavefile if open and frees the signal and the wave structure If wave is attached to a sound source and is playing it will be stopped before the wave file is closed In order to properly deallocate resources each successful call to cre open wave must be balanced with a call to this routine wave a pointer to the waveform structure to be closed On success Ok On failure Error1 invalid wave structure wavFt wavep cre _ open wave TEST WAV 4 listen to the music cre _close wave wavep 72 GOLDSERVE Manual cre_send_midi Synopsis include cre_midi h int cre _ send midi int src const unsigned char midistr Description Sends a string of MID
37. e or if the message can not be stored in buffer Example char last_error 256 cre_fetch_message 0 last_error 256 84 GOLDSERVE Manual Appendix 1 Glossary 3D sound refers to the fact that sounds in the real world are three dimensional Human beings have the ability to perceive sound spatially meaning that they can hear where a sound is coming from and where different sounds are in relation to their surroundings and in relation to each other There are three main pieces of information that are essential for the human brain to perform these functions e ITD or Interaural Time Difference means that unless a sound is located at exactly the same distance from each ear e g directly in front it will arrive at one ear before it arrives at the other For example if the sound arrives at the right ear before the left ear the brain knows that the sound is coming from somewhere to the right IID or Interaural Intensity Difference is similar to ITD It says that if a sound is closer to one ear the sound s intensity at that ear will be higher than the intensity at the other ear which is not only further away but usually receives a signal that has been shadowed by the listener s head e Finally the trickiest part of localization is the fact that a sound bounces off a listener s shoulders face and outer ear before it reaches the eardrum The pattern that is created by those reflections is unique for each
38. ecifies a MIDI channel voice message see above table for valid messages chnl the MIDI channel to which the command is to be applied datal first data argument for command data2 second data argument if necessary for command On success Ok On failure Error0 audio source src is out of range or no Tron sources have been initialized Errorl1 invalid MIDI message Error2 chn1 out of range cre_msg_midi mysrc MIDI_NOTE_ON 0 octave 12 note velocity While this function is designed to assist assembling simple MIDI messages without a MIDI sequencer we recommend that the inexperienced MIDI programmer invest in a good MIDI reference to fully understand the appropriate use of the interface GOLDSERVE Manual77 cre_set rel_pos Synopsis Description Parameters include cre_tron h int cre_set_rel_pos int head int src float azim float elev float gain Locates sound source src relative to listener head If the sound source is imagable De it is processed relative to its environment as in the Acoustic Room Simulation and the rendering model has been set to be near field the relative coordinates will be converted to world coordinates x y z Otherwise the sound will be processed directly in polar coordinates short circuiting much processing overhead Note This function does not affect a sound source s directional boresight or its current status with respect to other listeners hea
39. ed test applications You should hear a demo running on your system If you can see the tumbler spinning on the screen but there is no audio check the connection from the GoldServe to the headphone amp and from the headphone amp to the headphones If you hear the demo your server is functioning properly 5 Next connect the GoldServe to your client system PC SGI SUN or HP via the serial cable that was provided for your specific system On the server end the serial cable will be connected to the COM1 jack on the client end the default serial port is port number one COM1 on PC systems TTYD1 on UNIX systems To select a different serial port please refer to the environment variable section 6 Install the GoldServe client software onto your client system from floppy disk switch to floppy drive and type install for instructions from DAT or 4 inch tape use tar command to extract software 7 To test the client server connection move to the Client Test directory on your client system and select demo or test to start up a demo sequence that is controlled from your client system 8 If your GoldServe successfully initializes and plays sounds your system is installed and ready to use If the GoldServe is not responding correctly please proceed to the next section on startup problems Startup problems Problem Your local demo program does not produce sound and does not start properly no spinning
40. efers to an object in 3D space that emits sound The actual sound signal that it sends out can be a live signal a wave file or any other audio signal A 3D sound device is often rated on how many different sources it can independently position at any one time Realistic sound spaces can be created with as few as four concurrent sources very complex spaces can have dozens of separate sounds at a time e speaker arrays an installation of multiple speakers in a certain pattern usually designed to create a sound field within the space defined by the speakers Examples are stereo speakers or quadraphonic speakers stereo stereophonic refers to two audio signals usually rendered on two separate speakers Stereo sounds appear to originate from somewhere between the two speakers or between the ears of a listener in the case of headphones e surfaces sounds not only travel to a pair of ears on a direct path but they also bounce off objects in the world Most natural listening environments contain at least a sound reflecting ground plane such as a floor Therefore reflecting objects are necessary to make virtual environments sound natural and realistic They help listeners navigate and enhance the overall effect of immersion in a virtual environment Almost as important as reflections is the absence of a reflection For example the brain can tell the change in a sound space when A reflection is removed by opening a door or a window 88 GOLDS
41. elopment The GoldServe does not support mixing multiple inputs whether hardware inputs or wavefiles to a single localization channel Real time signal input Real time external inputs may be either analog or digital streams All input signal data enters the GoldServe digital audio processing unit DAPU as a digital stream through one of two optical interfaces Each optical interface may be configured to receive either the ADAT optical 8 channels or the S P DIF optical standard 2 channels The optical or lightpipe interface requires a standard TOSLINK cable for interconnection 1 Humans can perceive aural latencies as small as 5 milliseconds when offered a definitive reference When given no reference whether aural visual psychomotor or tactile humans have no means of perceiving lateness GOLDSERVE Manual 5 For analog audio the GoldServe includes an external component called Addabox see Figure 1 which provides 8 converters for input from analog to digital and 8 converters for output from digital to analog These high fidelity converters are provided external of the DAPU to isolate the sensitive Addabox components from the digital noise of the server The Addabox provides 24 bit encoding at either 44 1 or 48 kHz The analog inputs to the Addabox accept balanced tip non inverted hot ring inverted cold sleeve ground TRS jacks or unbalanced signals at the standard 10 dBV level
42. er operating systems may have to verify the existence and proper setup of a CIFS client to gain network access to the GoldServe file system Input and output amplifiers The analog input to the GoldServe s Addabox is line level 10 dBV and must be pre amplified for microphone input When streaming live sound use a high quality microphone coupled with a microphone pre amplifier GOLDSERVE Manual 9 Spatial audio requires a lot of dynamic range to simulate proper realistic distance attenuation The GoldServe s localized output routed through the Addabox analog converters is line level 10 dBV and must be amplified for most headphone displays to achieve full dynamic range The headphone amplifier is provided for this purpose Please note that the supplied cables to connect the GoldServe Addabox to the amplifier are balanced differential signal audio cables Use of unbalanced cables will compromise your dynamic range Headphones nearphones speakers or amplifiers can be connected to the headphone amplifier outputs When the headphone amplifier is properly set a normalized source located at virtual arm s length with cre_amplfy source set to 0 dB should sound very loud Output devices Your GoldServe can be connected to a number of different output devices The cre define head AtrnDISPLAYtype function call is used to select an output device The default device is headphones Different devices will provide
43. er via the ATRON protocol and gathers a text string from the server If verbose is non zero it will print this string to stdout Important This function runs verbosely from a console window Parameters verbose verbose flag Retum Value On success Returns the alphabetical index of the first letter of this string which is one of 1 Acoustetron 2 Beachtron Server 3 Convolvotron Server 4 GoldServe Server 13 Mtron On failure Error1 a connection could not be made Error2 response from client was incomplete Example cre_test_atron 1 82 GOLDSERVE Manual cre_fetch_message synopsis include cre_tron h int cre_fetch_messag int msg char buffer int bufsize Description Retrieves messages from the output buffer Can be used to assist with de bugging and to provide a means of checking for problems The messages are copied into a buffer so that they can be read printed to the screen etc Parameters msg If msg gt 0 then the message which is retrieved is the one at the index msg from the END of the list of messages The smaller the value of msg the more recent the message If msg lt 0 then this function will retrieve as many messages as possible beginning with the most recent until the buffer is full buffer A pointer to the location where the retrieved messages will be stored as a string bufsize The maximum number of characters which can be stored in the buffer Once the end of the buffer is reac
44. failure Error1 invalid parameter type Error2 unable to detect type cre detect AtrnO0RYframerate GOLDSERVE Manual41 cre_define_head Synopsis include cre_tron h int cre_define_head int id int prm int Description pts const void data Allows the user to specify parameters defining the listener model head size and pinnae characteristics and the reference frame for location coordinates in subsequent calls to cre locate _head Parameters 42 id the identifier of an initialized listener to be defined The macro ALL_HEADS is not supported prm one of the pre defined parameter values from ATRNheadDef enum Values can be one of the following list At rnAURA At rnAURA At rnAURA AtrnAURA Locular Lpinnae Lcrown Loffsets AtrnINTERAURAL AtrnHRTFfile AtrnAHMname AtrnDELAYtable AtrnDELAYscale AtrnHRTFmodel AtrnHEADgain AtrnDISPLAYtype AtrnEQleft AtrnEQright GOLDSERVE Manual pts number of data points given in data A negative value may be used by the particular parameter data pointer to data of type specific to each parameter GOLDSERVE Manual43 PRM Types AtrnAURALocular AURAL OFFSET along X axis Typically zero or an offset from ocular axis eye coordinates An offset from the ocular axis which is in front of the aural axis would be negative AtrnAURALpinnae AURAL OFFSET along Y axis One half the positive dist
45. fined by TRONCOM the variable 22 GOLDSERVE Manual CRE_TRON Software Interface API Overview CRE_TRON is a 3D audio application programming interface API that was developed by Crystal River Engineering in the early 1990 s to facilitate the creation of interactive three dimensional AuSIM3D sound spaces The goal of the CRE_TRON API is to allow a user or developer to build up a sound space using the concepts of physical reality without having to know about the underlying algorithms implementation or audio hardware This API implements the concept of a sound space in the form of easy to understand objects Objects include sound emitting sources sound reflecting surfaces and sound receiving listeners Sounds get created by sources such as a ringing phone propagate through space bouncing off passive objects such as walls and finally reach a listener s ears where they are received and interpreted The C function calls listed below are used to write programs to control the GoldServe They are described in detail in the CRE_TRON Function Reference A good place to start programming is by expanding on the demo c example code in the AuSIM3D Client Examples demo directory This directory also contains a sample workspace file demo dsw that can be used in conjunction with the demo c file to create a sample client application The function calls that allow a programmer to interact with the GoldServe can be grouped into the
46. he Doppler factor is reset to its default of 1 0 Setting Doppler factor to 0 0 disables it completely Retum Value On success Ok On failure Error0 audio source dis out of range or no Tron sources have been initialized Errorl invalid parameter prm Error2 pts is out of range Error3 parameter specific error see parameter descriptions Example 54 const float rad_table 4 IO PAN E lA OA E cre define source mysource AtrnRADprofile 4 rad_table Figure 4 cre define source examples for two different radiation tables rad_table 3 rad_table 4 0 0 20 0 60 0 10 0 5 0 20 0 60 0 0 dB 0 dB O C 20 dB O 60 dB GOLDSERVE Manual cre_locate_source Synopsis include cre_tron h int cre_locate_source int id const float sourceLoc Description Locates an audio source id in x y z yaw pitch roll world coordinates This function does not affect processing until a synchronization call to cre update audio is successful GOLDSERVE Manual55 Parameters id the zero based index of the audio source to be located The macro ALL_ SOURCES is not supported To locate multiple audio sources multiples calls cre_locate_source are necessary SourceLoc a pointer to a sextuple of floats AtrnX AtrnY AtrnZ AtrnYAW AtrnPTC AtrnROL Retum Value On success Ok world x axis coordinate world y axis coordinate world z axis coordinate angle of
47. hed no more characters will be stored Return value If successful returns the number of characters that have been copied into buffer If unsuccessful returns 0 if there is no message to retrieve or if the message can not be stored in buffer Example char previous_msgs 256 cre_fetch_message 1 previous_msgs 256 GOLDSERVE Manual83 cre_fetch_enor synopsis include cre_tron h int cre_fetch_error int msg char buffer int bufsize Description Retrieves error messages from the error buffer Can be used to assist with de bugging and to provide a means of checking for problems The error messages are copied into a buffer so that they can be read printed to the screen etc Parameters msg If msg gt 0 then the error which is retrieved is the one at the index msg from the END of the list of error messages The smaller the value of msg the more recent the message If msg lt 0 then this function will retrieve as many error messages as possible beginning with the most recent until the buffer is full buffer A pointer to the location where the retrieved messages will be stored as a string bufsize The maximum number of characters which can be stored in the buffer Once the end of the buffer is reached no more characters will be stored Return value If successful returns the number of characters that have been copied into buffer If unsuccessful returns 0 if there is no error message to retriev
48. ications 12 Localization see the performance document that came with your system Pitch 20 500 shift control for all sources Dynamic update rate see the performance document that came with your system Active audio buffering over 20 minutes configurable to over 100 minutes Analog Input 128X oversampled 24 bit A D converters Analog Output 8X oversampled interpolating filters Stereo crosstalk 100Hz 100dBV 1kHz 80dBV 10kHz 60dBV Wavefile archive over 20 hours GOLDSERVE Manual Installation Hardware Follow these steps to setup and test your GoldServe 1 Connect the GoldServe cables as follows Connect the 1 4 inch stereo cable labeled MON to the ADAT jack marked MON Connect a pair of headphones to the headphone jack on the headphone amplifier Connect the headphone amplifier power cord into the power distribution strip mounted in the back of the rackmount case Connect the black power cable labeled POWER to the GoldServe DAPU receptacle marked POWER Plug the heavy power cable from the power distribution strip located in the back of the rackmount case into an external 120vAC power supply Connect the mouse and keyboard cables labeled MSE and KBD to the GoldServe DAPU jacks labeled MSE and KBD Connect the monitor power cord into the power distribution strip mounted in the back of the rackmount case and plug the other monitor cable i
49. invalid channel Error2 failure to execute patch cre_select_source 0 3 60 GOLDSERVE Manual cre_pmeter source Synopsis Description Parameters Retum Value Example include cre_tron h int cre_pmeter_source int id float power Measures the instantaneous power of the sound source The measured value is written to the float that power points to id power On success On failure the zero based index of the sound source to be amplified The macro ALL_SOURCES is supported pointer to which the calculated power is written Ok Erroro audio source id is out of range or no Tron sources have been initialized cre_pmeter_source id amp power GOLDSERVE Manual61 cre_define_medium Synopsis Description Parameters PRM Types tinclude cre_tron h int cre_define_medium int prm int pts const void data Allows the user to specify parameters to model the medium through which the sound propagates absorption filter distance and spreading roll off exponent The function is a generic dispatcher that may be extended in future releases See parameter descriptions below for specific behavior rm one of the pre defined parameter values from the ATRNmedDef enumeration This can be one of the following list AtrnROLLOFF AtrnABSORBdist AtrnMEDDEF last pts the number of points to be read from the data pointer data a pointer to at least pts data points An undetec
50. ital audio device any extemal balanced orunbalanced analog audio device Figure 1 The GoldServe functional schematic Currently the only supported client API is CRE_TRON an API that was developed in 1991 and popularized by Crystal River Engineering Inc CRE The GoldServe server responds to the ATRON RS 232 protocol also a CRE development These two interfaces high and low level respectively were featured on the popular Acoustetron and Acoustetron II sound localization servers from CRE By maintaining backward compatibility with these interfaces GoldServe systems are instantly supported by scores of existing end user applications GoldServe System Components The system consists of an embedded computer hosting an audio filtering engine and digital audio stream controller a 16 channel digital audio interface an 8 channel analog audio interface and monitoring console The filtering engine is optimized to filter 8 streams with 64 coefficients per left right pair 16 streams with 24 coefficients per pair or 5 streams with 128 coefficients per pair All filtering is performed with 32 bit floating point accuracy All digital audio streams are maintained with 21 bits of resolution The analog interface supports 24 bit encode and decode at 44 1 or 48 0 kHz GoldServe includes server software to monitor the RS 232 ports and translate protocol strings into localization control as well as over 100 sample wavefiles for prerec
51. ld be added to binaural signals allowing loudspeaker display while retaining the true localization However measuring and maintaining these listening environment characteristics are very difficult in practice leaving headphone or nearphone displays the most viable The optimal binaural display should occlude the immediate aural environment so that ambient or local sound does not interfere with or collapse the virtual image depicted by the binaural signals Closed circumaural meaning surrounding the entire pinnae headphones are thus the best binaural display 6 GOLDSERVE Manual In the continuum between closed headphones and arbitrarily placed loudspeakers a wide variety of aural displays define an equally wide variance in localization display quality Figure 3 illustrates this continuum with the displays supported by the GoldServe highlighted in bold All displays represented assume stereo pairs with single driver elements Multi driver loudspeakers diffuse the localizability and increase compensation complexity Multi speaker arrays are designed create a physical sound field in the listener s environment are thus not compatible with binaural audio and require a very different type of technology to compute compatible signals Arbitrary Loudspeakers Sereo Loudspeakers Nearphones Multimedia Open Closed Loudspeakers Headphones Headphones Figure 3 The continuum of localization displays Localized o
52. lient server packets index of associated source 1 unassigned factor by which wave gets pitch shifted gt 1 indicates upward shift lt 1 indicates lowering of the pitch total frames in the signal data unloaded frames remaining on disk starting point for looping in samples ending point for looping in samples number of times through the loop Currently the following members are not being used 34 selFrames startFrame length of selected signal index of beginning frame in selection GOLDSERVE Manual Program routines cre_init Synopsis Description Parameters include cre_tron h int cre_init int driver int head int sources int mode Computes detects and allocates resources i e processors and host memory to provide the services specified by driver to listener head for the requested number of sources The driverisa legacy CRE term which specified the DSP binary to load from the host to the resourced hardware In the AuSIM implementation all old anechoic CRE drivers are honored with a competent emulation New AuSIM drivers initialize a specific set of simulation parameters All host objects are initialized with reasonable values The listener s head is located at the origin All sound sources are initially positioned at the full RESPONSE DISTANCE radius of actual HRTF responses defined in ATRON H directly in front of the listener Driver driver selected from ATRNdriver enum
53. location in space relative to the listener A human brain can therefore learn to associate a given pattern with a location in space Since 3D sound consists of two signals left and right ear it can be rendered on conventional stereo equipment preferably headphones because of the clean separation of the two signals The 3D sound produced by a direct path AuSIM3D system is combined with sound reflections wavetracing to create a very high level of realism and immersion in a sound space e ambient channel a way of displaying sounds as coming from everywhere all around the listener This is useful for background music or ambient sounds such as rain e atmospheric absorption the attenuation of sounds as they propagate through a medium For example in air the high frequency components of sound attenuate faster than the lower frequency components e AuSIM3D binaural immersive interactive real time 3D audio technology by AuSIM Inc GOLDSERVE Manual85 e auralization the process of rendering audio by physically or mathematically modeling the sound field of a source in space in such a way as to simulate the binaural listening experience at any given position in the modeled space e binaural two audio tracks one for each ear as opposed to stereo which is one for each speaker Binaural sounds are what we hear in everyday life e boresight axis axis defined by the boresight direction see boresight direction e boresight dire
54. mum number of concurrently open wave files is determined by the amount of memory available in the GoldServe system 16 bit wave files will require twice the amount of system memory as disk space Because loading the data from the hard disk into memory takes some time about 50 milliseconds per 100 kB of file space all cre open wave calls must take place before any calls to cre init 66 GOLDSERVE Manual cre_cti_wave Synopsis Description Parameters include cre_wave h int cre_ctrl_wave int src wavFt wave int cmd void data Requests the host to control the waveform wave according to the command cmd which may be related to source src This function is a generic dispatcher that may be extended in future releases See command descriptions below for specific behavior src the zero based index of the audio source in reference The macro ALL_ SOURCES is not supported wave a pointer to the waveform structure affected by all commands except WaveCTRL_STOP cmd one of the pre defined command values from the wave_ctrl enumeration This must be one of the following WaveCTRL RFRS WaveCTRL PSET WaveCTRL RWND WaveCTRL NOLP WaveCTRL STRT WaveCTRL PLAY WaveCTRL LOOP WaveCTRL STOP WaveCTRL STAT WaveCTRL SYNC WaveCTRL PTCH WaveCTRL LPST GOLDSERVE Manual67 data NULL except for WaveCTRL_ DICH and WaveCTRL LPST 68 GOLDSERVE Manual CMD Types WaveCTRL RFRS Refreshes the wave file image f
55. n to n from the world x axis about the world z axis of the projection of the source s x axis onto the world x y plane Looking down at the x y plane a counter clockwise rotation is positive angle of 11 2 to 11 2 from the world x y plane of the source s x axis about the world y axis Remember that with x forward and Z up a positive pitch is down angle of n to n from the world y axis about the world x axis of the source s y axis From the source s point of view a clockwise roll of the sound rolls y into z and is therefore positive On failure Error0 audio source id is out of range or no Tron sources have been initialized Errorl sourceLoc is NULL 56 GOLDSERVE Manual Example Remarks const float srcloc 6 1 10 0 20 0 0 0 0 0 0 0 0 0 cre locate source 4 srcloc Only the first three floats are used when the audio source is in uniform radiation mode However as a safe programming practice you should always maintain pointers to six element data structures AtrnROL is not presently used since non uniform radiation is symmetric about the boresight roll axis but it should be maintained for future compatibility GOLDSERVE Manual57 cre_amplfy_source Synopsis Description Parameters Retum Value Example Remarks include cre_tron h int cre amplfy_ source int id float dB Sets the loudness of a source to 0 dB at 2 units from the listener This distan
56. ne of the trnSPRDrolloff pts data the number of points to be read from the data pointer base pointer of an array that has at least pt s elements An undetectable error will occur if pts is larger than the number of elements defined in data The pointer can be NULL in which case the first pt s points of the existing pattern table will be used GOLDSERVE Manual51 PRM Types AtrnRADfields Allows the user to control the directivity of the sound data will contain two parameters both in radians describing a field of radiation and a field of intensity These fields are cones centered on the source s boresight direction principal direction of aural emission in which 90 for the field of radiation or 45 for the field of intensity of the sound energy is dissipated AtrnRADprofile Defines an audio source s radiation pattern about its boresight axis The radiation profile of a sound source id is specified in data with an array of relative sound pressure levels in decibels sampled equiangularly at pt s points from the boresight direction to anti boresight direction inclusive The boresight direction is coincident with the source s positive roll axis the axis parallel to the world coordinate X axis when source yaw and pitch are zero All definable radiation patterns are symmetric about the roll axis i e no rectangular horn speakers For off axis angles from source to listener that fall between sample poi
57. ns between drivers is the sample rate at which they will run the hardware Two of the more common sample rates are 24 48 000 Hz the sample rate for professional audio Advantage good resilience to intensive processing which results in sustained post process high fidelity audio quality and good localization AuSIM is shifting its processing to 48 kHz Disadvantage very high computational requirements 44 100 Hz the sample rate for CDs Advantage moderate quality for audio and localization Disadvantage high computational requirements 22 050 Hz the sample rate common in multimedia titles and video games Advantage lower system bandwidth computational resource and storage requirements Disadvantage poor audio and localization quality 22 kHz sampling is not supported by AuSIM3D AuSIM intends to upsample all 22 kHz wavefiles in future releases GOLDSERVE Manual Different drivers may be selected at start up time by one of the parameters of the cre_init call Please note that independent of driver sample rate both 22 05kHz and 44 1kHz wave files can be played back Example code include lt conio h gt include lt stdio h gt pragma hdrstop include cre _tron h include cre _wave h define SourcelD 0 define HeadID 0 define Sources 2 define WaveFil TEST WAV define PanLimit 100 0f void main void float step 0 2f float SrcLoc 6 10 0f PanLimit 0 0 0 0 0 0 0 0 float Head
58. nto the DAPU jack labeled VGA Plug the end of the RS 232 serial cable labeled AuSIM Server COM1 into the jack labeled COM1 on the back of the DAPU and plug the other end into the COM2 port also on the back of the server DAPU This will allow the server installation to be verified later the second end of the RS 232 serial cable will need to be plugged into an available COM port on the client machine Toggle the power distribution strip switch so that the red light is illuminated indicating that the strip is providing power Boot the DAPU by toggling the power switch on the front of the DAPU unit and let the system boot into WinNT 2 Press the CTRL ALT and DEL keys simultaneously when prompted and at the logon prompt type in Golddigger without the quotes for the user name and nugget without the quotes for the password GOLDSERVE Manual13 3 When the Windows NT desktop appears the server window should also appear accompanied by a double beep to indicate the AuSIM server application has been activated You should also see a spinning tumbler in the upper right hand corner of the server window that indicates the server is serving properly If there is no tumbler advance to the next chapter on startup problems 4 Click on the START button on the lower left hand side of the screen then select AuSIM from the menu then Test then select from the list
59. nts the profile is linearly interpolated Designed for empirically sampled data AtrnRADprofile also provides effective profile definition with very few artificial points The macro MAX_RADPROFILE specifies the maximum data array size supported See Figure 2 for examples of using AtrnRADprofile Note Uniformly radiating sources save considerable computation and are specially defined by pts 0 In the special case of pts 1 the boresight is defined by data GAIN_dB_OFF 2 Ifa NULL data pointer is given the profile is set to the first pt s points of the existing table With this feature you can pre load the profile array and then toggle directional radiation on and off with pts AtrnPROFILEpts Specifies the number of profile points to use AtrnSPATIALoff Disables localization for this source The monaural sound is patched directly through and mixed with the left and right outputs with a gain in dB defined by data This allows the user to implement simple panning If pts 0 the previous panning mixture values are used If pts 1 the given value is applied to a 52 GOLDSERVE Manual balanced mixture If pts gt 2 an error is returned If pts lt 0 localization is re enabled which is the default The source is passed through a flat filter so the latency remains the same as if it were localized AtrnSPATIALon Enables source localization This is the default AtrnHEADlink By setting this parameter the
60. o sources For each audio source the system produces a left and right output pair dependent on the direction of emission from the source path of propagation and direction of arrival to the listener The output pairs corresponding to each source are mixed and played through conventional headphones or nearphones The processing creates the perception that the source is positioned at any specified location in three dimensional space GoldServe is a complete 3D sound localization server subsystem to be a peripheral to a host computer running a user s application The host can be any modern computer workstation or several in fact Host computers can control a GoldServe system via an RS 232 communication protocol called ATRON which is easily implemented in the user application through a high level C application programming interface API While the API hides the low level ATRON RS 232 protocol it is completely disclosed and may be programmed directly for access on as yet unsupported host platforms From the GoldServe perspective the user s application is the client that sends commands to the GoldServe server for service The GoldServe client server scheme is functionally diagrammed in Figure 1 below GOLDSERVE Manual 1 Localization Server Client Workstation Sream Controller ADAT Ko SPDIF Optical Digital Interface S o User s Client Application any extemal ADATor SPDIF Optical dig
61. of server functionality Stress c reOrbit A test program available on your client system It will start up eight sounds that are pre installed on your GoldServe system and will orbit them around the listener s head randomly until the program is stopped ESC This program challenges the system resources and can be used to determine whether the resources available to a given system are capable of supporting the expected number of sound sources 20 GOLDSERVE Manual example A very simple client example program that moves a sound around in space This program is a good place to look for a simple code sample to get you started on writing your own GoldServe applications Application programs The following sample application is provided on UNIX platforms audio lient If running X Windows with the Motif widget set the audioClient program can be used to verify the functionality of your GoldServe Once started on the client it presents a graphical user interface and a two dimensional graphical representation of the listening space that allow you to load wave files play them and move the sounds and the listener around in a space that includes sound reflecting walls GOLDSERVE Manual21 Environment variables The GoldServe server can be controlled using the following optional environment variables on the client system Variable Description Default if not set TRONCOM Selects communication parameter
62. orded playback The system also provides a client library with several examples to allow user applications to easily control the server 2 GOLDSERVE Manual Configurations GoldServe systems can be packaged in many configurations The basic package called GoldMiner includes e a digital audio processing unit DAPU supporting sixteen 16 digital audio streams in and out e aminimal console monitor keyboard and pointing device for direct DAPU control e a pair of high quality open circumaural headphones e ananalog interface for four channels of monaural input and four pairs of binaural output e a four way 4 high gain headphone amplifier and e aportable rackmount enclosure The DAPU of any GoldServe system may be configured with one two or four processors which are called GoldSolo GoldDual and GoldQuad respectively When included in the basic package such processor configurations are called GoldMinerSolo GoldMinerDual and so forth Organization of this manual Chapter 1 Introduction describes the audio localization process and its implementation on an AuSIM GoldServe system Chapter 2 Getting Started reviews hardware and software requirements for using GoldServe explains what comes with a GoldServe system standard and optional and how to install it and tells you how to obtain technical support and service Chapter 3 Using the GoldServe explains how to test your GoldSer
63. ource src described by message type msg on Tron MIDI channel chn1 and with data arguments data1 and data2 A MIDI channel voice message consists of an 8 bit status byte including the message type and target MIDI channel followed by one or two 7 bit data bytes cre msg midi forms common MIDI strings for targeting synthesized sounds to localized Tron sources The function properly bit clips all parameters and then assembles a MIDI status byte via the following formula status_byte 0x80 msg amp 0x07 lt lt 4 chnl amp 0x07 8 id BMP1_SRCS Finally it appends the correct number of 7 bit clipped data bytes according to the table below and sends the resulting message string to the Proteus Message Macro Data Byte 1 Data Byte 2 msg datal data2 MIDI_NOTE_OFF key number velocity MIDI_NOTE_ON key number velocity MIDI_AFTERTOUCH key number pressure amount MIDI_CONTROL control number control value MIDI_PATCH program number none 76 GOLDSERVE Manual Parameters Retum Value Example Remarks MIDI_CHNLPRESS pressure value none MIDI_PITCHBEND pitch bend pitch change Key numbers can be easily derived using the OCTAVE and NOTE enumeration lists defined in CRE_MIDI H and the following formula key_number octave 12 note SIC the zero based index of the audio source in reference The macro ALL_SOURCES is supported msg an integer that sp
64. r the GoldServe System does come with ethernet networking software installed so it can be connected to a LAN for purposes of transferring files etc Chapter 3 Run time usage The monitor and keyboard are required for runtime usage at this time This is because the operator must press the CNTL ALT DELETE keys and enter the username Golddigger and the password nugget in order to login to the Windows NT desktop With practice this may be done without a monitor but a keyboard is still required at boot time Also the double beep has yet to be added Code Defects D1001 cre_open_wave wavefiles lt 1Mb fail to return success flag GOLDSERVE Manual91
65. r to originate from the speaker or from the center of a listener s head in the case of headphones e psychoacoustics an area of psychology that studies the structure and performance of human auditory perception GOLDSERVE Manual87 e quadraphonic sound refers to four audio signals usually rendered on four separate speakers Quadraphonic sounds appear to originate from somewhere in between the four speakers The inconvenience associated with the amount of equipment necessary to produce quadraphonic sound coupled with the fact that it is not compatible with conventional stereo equipment and therefore headphones makes quadraphonic sound an unpopular choice e radiation pattern each sound emitting object can optionally radiate sound in a certain pattern rather than uniformly all around it For example a head should emit sounds in the direction that its nose is pointing e reflection a sound reflection off a surface It gives a listener information about the listening environment and the location and motion of sound sources See surfaces e refraction sounds waves refract or bend as they travel around the edges and through openings of objects e reverberation or reverb refers to the sum of all sound reflections in a listening environment e sample rate the number of samples per second at which a sound is processed usually ranges from 8kHz to 50kHz CD quality is 44 1kHz or 44 100 samples per second source r
66. rams deleteAtron c Source code for utility programs downloadAtron c lengthAtron c listAtron c playAtron c uploadAtron test wav welcome wav quack wav jaws wav Sound files a Figure 5 CRE directory organization UNIX client GOLDSERVE Manual17 Problems Technical support If you are having difficulties with the operation of your GoldServe be sure to review the Installation procedure described earlier If you can t solve your problem you should contact technical support at AuSIM at the address or phone numbers listed in the inside front page of this manual Please be sure to have available as much as possible of the following information e GoldServe software version e GoldServe serial number from label near power on switch e If possible example code that allows us to reproduce your problem at the factory Repair Before returning faulty equipment or media for service you first need to obtain authorization from AuSIM or from your distributor Bugs Please report suspected or confirmed software problems to AuSIM at the e mail address or phone numbers listed in the inside front page of this manual It is essential that you include a complete description of the problem in sufficient detail that we can reproduce it 18 GOLDSERVE Manual Chapter 3 Using the GoldServe System start up On startup the GoldServe system performs a number of self tests and then boots up the server It i
67. rom disk WaveCTRL PSET Sets the signal pointer to the specified sample data will hold the zero based index of the sample relative to the base sample WaveCTRL RWND Rewinds the current frame position of waveform to its first frame This will work even while playing Rewind is useful if the waveform was stopped before finishing its full selection WaveCTRL NOLP Unsets the loop flag allowing the source to play to its end and stop WaveCTRL STRT Plays the waveform from its beginning rewinding if necessary patching it through to source src WaveCTRL PLAY Plays the waveform starting at the current frame position patching it through to source src By default playing does not loop WaveCTRL LOOP Turns on looping and starts playing the waveform from its current frame position Turning on looping means that when playback reaches the end of the sound file the signal is automatically rewound to its beginning Looping continues until the playback is either stopped WaveCTRL_STOP or the loop flag becomes disabled WaveCTRL_NOLP See WaveCTRL_LPST for information on setting loop points WaveCTRL STOP Stops playing any waveform attached to source src maintaining that waveform s current frame position WaveCTRL STAT Tests the current waveform wave status with respect to given source src Alternatively this command can check wave GOLDSERVE Manual69 70 status for any source with src 1 or check src for any
68. rted up and is waiting for communications from the client ready to render sounds Once the server is running a few keyboard commands can be issued to control it SPACEBAR toggles the console display from a static screen to a screen that shows all on going communication between the client and server on start up it is set to static Please note that printing updates to the screen slows down the framerate of the GoldServe ESCAPE KEY will restart the server without rebooting the entire system The server and client normally operate at 115200 baud Changing the baud rate is not recommended unless some special circumstances require it Baud rate change can be accomplished by changing the environment variables To see how to do this for your GoldServe system see the section entitled Environment Variables below Run time usage To use your GoldServe with an existing application simply connect the client and server systems and connect all audio equipment headphone amp cables and headphones The monitor and keyboard are not necessary for operation since the system can simply be powered up and is ready to be accessed from the client after the GoldServe has emitted a dual beep Testand example programs Once hardware and software installation is complete you may test the GoldServe system in a number of ways demo The demo sequence can be started from both the server and the client end It serves as a verification
69. s The pts argument must be set to one to have the float value pointed to by data set the spreading roll off exponent or may be zero or negative to reset the default value defined by the macro SPREADING ROLLOFF in ATRON H An out of range exponent value will return an error The exponent must be greater than zero and less than the value defined by the macro EXPONENT LIMIT in ATRON H Remarks In a free sound field spreading loss is 6 dB for every doubling of the distance i e gain is proportional to 1 0 R However there are few free sound fields in the real world so the apparent spreading loss depends on the acoustic impedance of the propagation medium and elements in the sound field Since the Tron is simulating a virtual anechoic environment a nominal roll off exponent of 1 0 sounds steep Typically roll off exponents in between 0 5 and 1 2 are of interest GOLDSERVE Manual63 Retum Value On success Ok On failure Erroro no Tron sources have been initialized Errorl1 invalid parameter prm Error2 pts is non zero but data is NULL Example set distance in current units float absorb_dist 100 0 cre define medium AtrnABSORBdist 1 amp absorb_dist 64 GOLDSERVE Manual cre_open_wave Synopsis Description Parameters Retum Value Example include cre_wave h wavFt cre_open_wave const char wavefile int mode Opens a sound file referred to by the filename wavefile from the
70. s 1 1152 30 TRONDEV Overrides the serial port device name dev ttyd1 UNIX on non PC client hosts The TRONCOM variable needs to be set if you want to operate your GoldServe on a different setting than serial port 1 at 115200 baud WinNT For WinNT clients environment variables are set in the System panel within the control panel need image of System Control Panel Environment Sheet Win95 Win98 MS DOS For Win9x and MS DOS clients the environment variables should be entered in the C AUTOEXEC BAT to make them available to client programs invoked from the command processor The syntax for the AUTOEXEC BAT file or equally at a command prompt in a console window is as follows set TRONCOM x yyy ZZZ UNIX For UNIX the environment variables should be set in a cshrc or similar start up script so that their values are available in any shell The syntax is as follows setenv TRONCOM x yyy 2Zzz where x is the serial port number TTYDx or COMx yyy the baudrate divided by 100 100 s of bits per second and zzz the time out period the amount of time the client will wait for a response from the server on an init call The time out parameter is optional The TRONDEV variable is optional and only needed if your client system s serial port has a different file descriptor than the defaults For example setenv TRONDEV dev ttya sets the serial port device to TTYA from TTYD1 TRONDEV will override the port number de
71. s useful to talk about two different modes of operation for your GoldServe development or playback During development of an application the server should be connected to its monitor and keyboard in order to make several options and run time information accessible to the developer Once an application is developed and the GoldServe is used for run time playback only it can be run stand alone without the need for a monitor or keyboard Development usage On boot up of the system the following menu is displayed for a short while Please make a choice you have 5 seconds before the default gets selected 1 boot in MS DOS mode 2 boot in WinNT mode selected 3 boot in Windows 98 mode Wait five seconds and the server will boot to WinNT the default OS and the correct one for normal development usage of the GoldServe system If the ethernet option is installed the menu will be slightly different Press the CTRL ALT and DEL keys simultaneously when prompted and at the logon prompt type in Goldminer without the quotes for the user name and nugget without the quotes for the password When the Windows NT desktop appears the server window should also appear accompanied by a double beep to indicate the AuSIM server application has been activated You should also see a spinning tumbler in the upper right hand corner of the server GOLDSERVE Manuall9 The GoldServe server has now sta
72. se to the sides of a monitor In such a setup the user s position is assumed to be directly in front of the monitor forming a more or less fixed geometry between the listener and the two speakers Special processing of the left and right audio signals is applied to enhance the 3D effect in such a setup Please note that multimedia speaker processing is sweet spot see glossary limited Other stereo speakers This category includes all other forms of stereo speaker setups A speaker layout that does not fit the nearphone quad or multimedia categories is unlikely to produce a convincing 3D effect and is therefore not recommended GOLDSERVE Manualll System components and specifications A GoldServe base system GoldMiner consists of the following items GoldServe digital audio processing unit DAPU with wavefile archive dual ADAT optical digital audio interface and GoldServe server software GoldServe Client Software Library and Demos on CD GoldServe Manual Minimal console monitor keyboard and pointing device Enclosing pre wired rackmount case with power distribution bar Open circumaural headphones and a headphone amplifier Pre installed wavefile collection 100 wavefiles of general type vehicles animals machines explosions effects instruments Cables two 1 4 inch balanced audio four TOSLINK optical and one RS 232 null modem serial cable specific to your host computer The system specif
73. source maintains its relative position and orientation to the listener s head for all head positions and attitudes given When At rnHEAD1 ink is enabled all calls to cre locate source establish a new relative position as a difference of the global coordinates of head and source locations given datais ignored The pts argument is interpreted as the head index pts lt 0 unlinks the sound to all listener head positions AtrnHEADunlink Disables source to head linkage This is the default AtrnSPRDrolloff AtrnSPRDrolloff defines a single float value multiplier for that particular source of the global spreading loss roll off exponent defined in cre define medium The value must be positive and reasonable Reasonableness depends on the global rolloff value AtrnGAINdist AtrnGAINdist defines the distance at which the gain is specified AtrnCHNLinput AtrnCHNLinput allows zero one or more physical live audio input channels to be mapped to a particular source pts specifies how many and data is the array of integers specifying which channels to map AtrnCHNLmidi AtrnCHNLmidi allows zero one or more MIDI audio input channels to be mapped to a particular source pts specifies how many and data is the array of integers specifying which MIDI channels to map AtrnDPLRfactor GOLDSERVE Manual53 AtrnDPLR actor sets the Doppler exaggeration pts always specifies the listener id which may be ALL_HEADS If data is NULL t
74. t Filter Pipeline 2 Listener Model Left Filter Input Propagation Sgnal Q sl Model Right Filter Figure 2 AuSIM3D anechoic localization process on the GOLDSERVE 4 GOLDSERVE Manual All models are dynamic in that their parameters can change up to 60 times per second All AuSIM3D systems are optimized to render changes in less than 40 milliseconds a latency less than the least psychologically disruptive delay Being entirely composed of dynamic models the system may be driven interactively The Listener Model in GoldServe uses complete spherical sets of HRTF s called Acoustic Head Maps AHM s The filter characteristics comprising an AHM were obtained from actual measurements on a human head The GoldServe uses Finite Impulse Response FIR filters also known as non recursive filters Localization inputs amp outputs Audio input signals for localization should be as dry as possible meaning without propagation effects Dry signal transduction is usually accomplished by miking as directly and close to the emitter as possible Wet signals will possess propagation effects that are in conflict with those simulated by the GoldServe and thus have a collapsed or confused image The GoldServe offers dynamic selection between two different kinds of monaural sound sources real time external inputs and sampled sound files in pulse code modulated PCM format A third form of input real time synthesis is under dev
75. table error will occur if pts is larger than the number of points available to read The pointer can be NULL in which case the first pt s points of the existing pattern table will be used AtrnABSORBdist Atmospheric absorption control distance The absorption distance controls the amount of extra high frequency fall off over distance that is applied to simulate atmospheric absorption Currently this parameter can only be set to apply to all sources The pts argument must be 1 in order to have data set the distance in current units pts 0 or pts lt 0 will reset the absorption 62 GOLDSERVE Manual distance to its default value defined by the macro ABSORPTION DISTANCE in ATRON H The effect of the absorption filter can be minimized by setting this value to an arbitrarily large distance However it can be disabled entirely by passing a value of 0 0 or less Remarks The given distance affects the amount of atmospheric absorption filtering at a given source to receiver range by a factor of the range divided by the sum of the range and the absorption distance Hence the absorption filter will be applied at 50 when the range is equal to the absorption distance AtrnROLLOFF The roll off exponent due to spreading power loss The spreading roll off exponent parameter sets the rate at which sound amplitude is attenuated over distance to yield cues in the third dimension Currently this parameter can only be set to apply to all source
76. tem components and specifications oococociciconononononanananononocncncncnos Installaatio Aiie eni ia aE NEE E E tere Hard EE Startup problems iii A lge Client software and directory organization Proba at Using the GoldServe coocococcononcnnnnnononooncncnconononoonononronononoacnonrorononosass Systemi STOEN RR Run time usages airada lili ts GOLDSERVE Manual 1 Chapter 4 Test and example programs EE 20 din nada seta 20 le dai rita iii io diia 20 example ida 21 O ic oa das isa 21 o AAA 21 BEE 21 Downloading wave files and other utility programs s s sss12 22 Environment variables einsi iseensest eii isre 22 CRE_TRON Software Interface AIDI EN 23 OVEIVISW noia estaria Bea 23 Sample rates and driver selection o ooniccicncnnononnnnoncnnnornnncnnrncnos 24 Example code a RR 25 Coordinate sy still ia aia 27 Head track iii Aa ad 28 Audio SOUTCES initial 30 RRR ep 30 AA 31 Special topless elke eA Ee 32 Directional radiators oe ee eseeececseeeeseseeececsenseaesesesesseneaeaees 32 Atmospheric absorption eccsseeeeseeeeecneeseseseeesecnesseasseseeeeas 32 Spreading loss roll off NEEN 32 CRE_TRON API Function Reference sssssssscsssssssseesssssseeeees 33 Pata ae ai ani 33 E EE 33 Programi routes roren aida 35 e E 35 cre_update_audiO cocccoconnoconononncnnnnonononnon ieaie nn nenenennsns 38 E TEEN 39 SU 40 cre det trad td lo sic 41 Cre define Maeva ira EERTSE oe 42 cre locate Jean geet eeh
77. ter can update one to all AURAL OFFSETs as an ordered array of floats pointed to by data of pts items The ordered sextuple is specified by the enumeration 44 GOLDSERVE Manual ATRNspaceDef x y z yaw pitch roll Currently only Cartesian translations x y z are supported All of the single value AURAL OFFSET parameter rules stated above apply to At rnAURALoffsets including pts 0 to reset the default values AtrnAHMname Specify the name of an AHM subject to load If it is not one of the pre loaded subjects the system will search the AHM files located in the directory defined by the HRTF environment variable for the specified AHM subject An error is returned if the AHM subject is not found AtrnINTERAURAL The At rnAURALpinnae OFFSET doubled and time scaled This parameter combines the spatial control of the At rnAURALpinnae parameter above with its associated interaural delay scaling At rn INTERAURAL is the full ear to ear width measured to ear canal opening and thus is twice the At rnAURALpinnae value pts 1 will set the pinnae offset to one half the absolute float value pointed to by data If pts 0 datais ignored and the parameter is reset to the default value In both cases interaural delay values are not scaled to the ratio of the given interaural size with the default size If pts 1 the parameter is set according to data but the delay scaling is not altered AtrnHRTFfile Specify HRTF filename
78. the listener is located at a particular spot in relation to the speakers see sweet spot Fisher Scott the founder of Telepresence Research and original director of the Virtual Interactive Environment Workstation VIEW project at NASA s Ames Research Center Often confused with Scott Foster his friend and the founder of Crystal River Engineering and inventor of the Convolvotron both hail from MIT in the 1970 s and the Atari Research Labs in the early 1980 s The VIEW project started in 1984 determined the need for virtual interactive aural imaging and initiated the development of the Convolvotron 86 GOLDSERVE Manual Foster Scott the founder of Crystal River Engineering and inventor of the Convolvotron Often confused with Scott Fisher his friend and founder of Telepresence Research both hail from MIT in the 1970 s and the Atari Research Labs in the early 1980 s Scott Foster is considered by many to be the founder of interactive localized audio since his Convolvotron was the first device to bring the technology to auralization e gain the amplification or attenuation of a sound source usually measured in dB decibels 0 dB means no amplification and no attenuation A positive value amplifies a source a negative value attenuates it e HRTF HRTFs or Head Related Transfer Functions are sets of mathematical transformations that can be applied to a mono sound signal The resulting left and right signals are the same
79. utput The basic GoldServe system GoldMiner offers streaming binaural output for up to four independent listeners A single Addabox as included with the basic system converts digital streams for four analog output pairs The Addabox outputs are differential line level signals but may be tapped with unbalanced gear These line level outputs must be amplified to support the full dynamic range localization requires The GoldServe does not support output to file on disk GOLDSERVE Manual 7 Chapter 2 Getting Started Requirements Hardware Since the GoldServe is a complete peripheral system the only hardware requirement is an available RS 232 serial port on the client host system user s workstation through which to control the GoldServe audio server The GoldServe also provides network access to its file system via the standard Common Internet File System CIFS To gain direct access to the GoldServe file system you will need an ethernet port on your TCP IP network Software The GoldServe is currently available with client software libraries and serial drivers for Win9x WinNT4 Win2K MS DOS LINUX IRIX SOLARIS and HPUX operating systems The graphical user interface GUI demonstration software for UNIX systems audioClient requires an X Windows environment to operate The audioClient application is specifically configured for Motif While all Win32 clients have CIFS built in clients running oth
80. values to the signal processing engine Parameters None Retum Value On success Ok even if no changes were pending On failure Erroro no sources have been initialized Error1 system could not be interrupted to perform an update Example cre_update_audio Remarks cre update audio should be called once every time you want the audio updated cre update audio need not be called more frequently than the maximum framerate of the GoldServe see cre_detect to query framerate Redundant calls are ignored Synchronization Note In order to maintain synchronization of audio processing in a system in which more than one object listener and or sources are moving simultaneously you should complete all necessary calls to cre_locate_head and cre_locate_source before calling cre_update_ audio Because the Tron s internal audio parameters can be updated only as fast as the specific Tron s update rate the localization process may ignore more frequent calls to this routine 38 GOLDSERVE Manual cre_close Synopsis Description Parameters Retum Value Example include cre_tron h int cre _ close int driver int head Deallocates host resources for a given driver and listener which may then be reallocated with another cre init call cre close will gently shut off audio for the specified listener When the last open listener is closed all open wave files are also closed Calling cre_close ALL
81. ve and how to write your own programs for controlling the GoldServe AuSIM3D system Chapter 4 CRE_TRON Function Reference describes the function calls that are used to program your GoldServe M Chapter 5 Glossary contains a list of often used terms relating to AuSIM3D sound GOLDSERVE Manual 3 Audio localization The localization processing of two independent sound sources is illustrated in Figure 2 This schematic can be superposed to represent any number of sources Each source is processed through a sequence of dynamic models each representing independent characteristics of wave propagation First a Source Model filter accounts for emission amplitude and the directivity of the emitter A human voice for instance sounds dimmer when speaking away from the listener than towards Next a Propagation Model filter accounts for attenuation due to spreading and coloration due to friction in the medium Next the signal is split due to the differences in travel time to each ear and a Head Related Transfer Function HRTF a pair of filters each representing the directivity of an ear is applied for the directional effect Finally the Left and Right outputs from the respective source pipelines are summed together and output as a binaural mix for headphone presentation AUSM3D Anechoic Listener Model Headphones Pipeline 1 Left Alter Input Propagation Sgnal Q a Model Righ
82. waveform with wave NULL Returns a 4 bit value with each bit representing a state of either wave or src bit 0 wave is playing on source src bit 1 wave playing on some other source bit 2 srcis playing the wave bit 3 srcis playing some other waveform A return of zero means that neither wave nor src are busy WaveCTRL SYNC Specifies an already playing wavefile with which to synchronize This synchronization will take effect on a subsequent call to cre update audio Setting data NULL will turn off synchronization Example of WaveCTRL_SYNC usage cre_ctrl_wave srcl wavel waveCTRL_SYNC wave0 cre _ ctrl _ wave src0 wave0 waveCTRL_PLAY NULL cre_ctrl_wave srcl wavel waveCTRL_PLAY NULL WaveCTRL PTCH Sets the pitch shift factor pointed to by data float for wavefile wave BMP2 and BMP3 drivers only A value of 1 0 default results in no pitch shifting a value of 2 0 maximum will double the pitch of the wavefile a value of 0 5 minimum will half the pitch of the wavefile data NULL will disable pitch shifting WaveCTRL LPST Sets loop start loop end and loop count parameters src is ignored data is a pointer to an array of three longs data 0 loop start unsigned long in samples data 1 loop end unsigned long in samples data 2 loop count signed long 1 infinte looping GOLDSERVE Manual Retum Value On success Ok or bit code see WaveCTRL_ STAT On failure Erroro au

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