PsychPortAudio

Psychtoolbox>PsychPortAudio

PsychPortAudio - A sound driver built around the PortAudio sound library:

General information:

version = PsychPortAudio(‘Version’);
oldlevel = PsychPortAudio(‘Verbosity’ [,level]);
count = PsychPortAudio(‘GetOpenDeviceCount’);
devices = PsychPortAudio(‘GetDevices’ [,devicetype] [, deviceIndex]);

General settings:

[oldyieldInterval, oldMutexEnable, lockToCore1, audioserver_autosuspend] = PsychPortAudio(‘EngineTunables’ [, yieldInterval] [, MutexEnable] [, lockToCore1] [, audioserver_autosuspend]);
oldRunMode = PsychPortAudio(‘RunMode’, pahandle [,runMode]);

Device setup and shutdown:

pahandle = PsychPortAudio(‘Open’ [, deviceid][, mode][, reqlatencyclass][, freq][, channels][, buffersize][, suggestedLatency][, selectchannels][, specialFlags=0]);
pahandle = PsychPortAudio(‘OpenSlave’, pamaster [, mode][, channels][, selectchannels]);
PsychPortAudio(‘Close’ [, pahandle]);
oldOpMode = PsychPortAudio(‘SetOpMode’, pahandle [, opModeOverride]);
oldbias = PsychPortAudio(‘LatencyBias’, pahandle [,biasSecs]);
[oldMasterVolume, oldChannelVolumes] = PsychPortAudio(‘Volume’, pahandle [, masterVolume][, channelVolumes]);
[underflow, nextSampleStartIndex, nextSampleETASecs] = PsychPortAudio(‘FillBuffer’, pahandle, bufferdata [, streamingrefill=0][, startIndex=Append]);
bufferhandle = PsychPortAudio(‘CreateBuffer’ [, pahandle], bufferdata);
PsychPortAudio(‘DeleteBuffer’[, bufferhandle] [, waitmode]);
PsychPortAudio(‘RefillBuffer’, pahandle [, bufferhandle=0], bufferdata [, startIndex=0]);
PsychPortAudio(‘SetLoop’, pahandle[, startSample=0][, endSample=max][, UnitIsSeconds=0]);
startTime = PsychPortAudio(‘Start’, pahandle [, repetitions=1] [, when=0] [, waitForStart=0] [, stopTime=inf] [, resume=0]);
startTime = PsychPortAudio(‘RescheduleStart’, pahandle, when [, waitForStart=0] [, repetitions] [, stopTime]);
status = PsychPortAudio(‘GetStatus’ pahandle);
[audiodata absrecposition overflow cstarttime] = PsychPortAudio(‘GetAudioData’, pahandle [, amountToAllocateSecs][, minimumAmountToReturnSecs][, maximumAmountToReturnSecs][, singleType=0]);
[startTime endPositionSecs xruns estStopTime] = PsychPortAudio(‘Stop’, pahandle [,waitForEndOfPlayback=0] [, blockUntilStopped=1] [, repetitions] [, stopTime]);
PsychPortAudio(‘UseSchedule’, pahandle, enableSchedule [, maxSize = 128]);
[success, freeslots] = PsychPortAudio(‘AddToSchedule’, pahandle [, bufferHandle=0][, repetitions=1][, startSample=0][, endSample=max][, UnitIsSeconds=0][, specialFlags=0]);

PsychPortAudio - High precision sound driver for Psychtoolbox-3.

PsychPortAudio is a special sound driver for PTB-3. It is a replacement
for all other Matlab based sound drivers and PTB’s old SND() function.

PsychPortAudio provides the following features:

  • Allows instant start of sound playback with a very low onset latency
    compared to other sound drivers (on well working hardware).

  • Allows start of playback at a scheduled future system time: E.g.,
    schedule sound onset for a specific time in the future (e.g., visual
    stimulus onset time), then do other things in your Matlab code.
    Scheduled start of playback can be accurate to the sub-millisecond level
    on some system setups.

  • Wait for sound onset, or continue with execution of your code
    immediately.

  • Asynchronous operation: Sound playback works in the background while
    your code continues to do other things.

  • Infinitely repeating playback, or playback of a sound for ‘n’ times.

  • Returns timestamps and status for all crucial events.

  • Support multi-channel devices, e.g., 8-channel sound cards.

  • Supports multi-channel sound capture and full-duplex capture
    and playback of sound on some systems.

  • Enumerate, open and use multiple sound cards in parallel.

  • Reliable (compared to Matlabs sound facilities).

  • Efficient, causes only very low cpu load.

See the “help InitializePsychSound” for more info on low-latency
configurations. See “help BasicSoundOutputDemo” for a very basic demo of
sound output (without special emphasis on low-latency). See
“BasicSoundInputDemo” for a basic demo of sound capture.
“DelayedSoundFeedbackDemo” shows how to implement a simple audio feedback
loop with controllable delay. There are also demos that show scheduling,
modulation and mixing (cfe. BasicSoundScheduleDemo an BasicAMAndMixScheduleDemo).
SimpleVoiceTriggerDemo shows how to record vocal reaction times.
KeyboardLatencyTest uses audio to measure the response timing behaviour and
timing accuracy of various human input devices, e.g., keyboard, mouse, touchpad,
touchscreen, various response button boxes etc.

PsychPortAudioTimingTest and PsychPortAudioDataPixxTimingTest are scripts
that we use for testing PA’s sound onset latency and accuracy. It also serves
as an example on how to get perfectly synched audio-visual stimulus onsets.

Type “PsychPortAudio” for an overview of supported subfunctions and
“PsychPortAudio Subfunctionname?” for help on a specific subfunction.

CAUTION: You *must* call InitializePsychSound before first invocation of
PsychPortAudio(), at least on MS-Windows, but possibly also on OS/X! If
you omit that call, initialization of the driver may fail with some
“Invalid MEX file” error from Matlab!

PsychPortAudio is built around a modified version of the free, open-source
PortAudio sound library for portable realtime sound: http://www.portaudio.com