Sound input demos: Allow specification of number of input channels.

For BasicSoundInputDemo and DelayedSoundFeedbackDemo, allow to specify the
number of inputs, to also deal with sound cards which only provide one mono input
channel. Continue to default to 2 stereo channels.

Psychtoolbox/PsychDemos/BasicSoundInputDemo.m

@@ -1,5 +1,5 @@
-function BasicSoundInputDemo(wavfilename, voicetrigger, maxsecs, device, reqlatencyclass)
-% BasicSoundInputDemo([wavfilename][, voicetrigger=0][, maxsecs=inf][, device][, reqlatencyclass])
+function BasicSoundInputDemo(wavfilename, voicetrigger, maxsecs, device, reqlatencyclass, channels)
+% BasicSoundInputDemo([wavfilename][, voicetrigger=0][, maxsecs=inf][, device][, reqlatencyclass][, channels=2])
 %
 % Demonstrates very basic usage of the new Psychtoolbox sound driver
 % PsychPortAudio() for audio capture / recording.
@@ -32,6 +32,8 @@ function BasicSoundInputDemo(wavfilename, voicetrigger, maxsecs, device, reqlate
 % reqlatencyclass = Override reqlatencyclass parameter for audio capture. Defaults
 %                   to standard [] for low-latency, high timing precision if omitted.
 %
+% channels     = Number of input and output channels to use. Defaults to 2.
+%
 
 % History:
 % 06/30/2007 Written (MK)
@@ -77,8 +79,12 @@ function BasicSoundInputDemo(wavfilename, voicetrigger, maxsecs, device, reqlate
     reqlatencyclass = 2;
 end
 
+if nargin < 6 || isempty(channels)
+    channels = 2;
+end
+
 % Workaround broken qt plotting on some Octave setups:
-if IsOctave && exist('graphics_toolkit')
+if IsOctave && exist('graphics_toolkit') %#ok<EXIST>
     try
         graphics_toolkit ('fltk');
     catch
@@ -94,9 +100,9 @@ function BasicSoundInputDemo(wavfilename, voicetrigger, maxsecs, device, reqlate
 
 % Open audio device 'device', with mode 2 (== Only audio capture),
 % and a required latencyclass of 'reqlatencyclass', with the preferred
-% default sampling frequency of the audio device, and 2 sound channels
+% default sampling frequency of the audio device, and 'channels' sound channels
 % for stereo capture. This returns a handle to the audio device:
-pahandle = PsychPortAudio('Open', device, 2, reqlatencyclass, [], 2);
+pahandle = PsychPortAudio('Open', device, 2, reqlatencyclass, [], channels);
 
 % Get what freq'uency we are actually using:
 s = PsychPortAudio('GetStatus', pahandle);
@@ -120,7 +126,7 @@ function BasicSoundInputDemo(wavfilename, voicetrigger, maxsecs, device, reqlate
     % Repeat as long as below trigger-threshold:
     while level < voicetrigger
         % Fetch current audiodata:
-        [audiodata offset overflow tCaptureStart] = PsychPortAudio('GetAudioData', pahandle);
+        [audiodata, offset, ~, tCaptureStart] = PsychPortAudio('GetAudioData', pahandle);
 
         % Compute maximum signal amplitude in this chunk of data:
         if ~isempty(audiodata)
@@ -174,7 +180,11 @@ function BasicSoundInputDemo(wavfilename, voicetrigger, maxsecs, device, reqlate
     nrsamples = size(audiodata, 2);
 
     % Plot it, just for the fun of it:
-    plot(1:nrsamples, audiodata(1,:), 'r', 1:nrsamples, audiodata(2,:), 'b');
+    if channels > 1
+        plot(1:nrsamples, audiodata(1,:), 'r', 1:nrsamples, audiodata(2,:), 'b');
+    else
+        plot(1:nrsamples, audiodata(1,:), 'r');
+    end
     drawnow;
 
     % And attach it to our full sound vector:
@@ -202,7 +212,7 @@ function BasicSoundInputDemo(wavfilename, voicetrigger, maxsecs, device, reqlate
 
 % Replay recorded data: Open 'device' for output, push recorded sound
 % data into its output buffer:
-pahandle = PsychPortAudio('Open', device, 1, 0, freq, 2);
+pahandle = PsychPortAudio('Open', device, 1, 0, freq, channels);
 PsychPortAudio('FillBuffer', pahandle, recordedaudio);
 
 % Start playback immediately, wait for start, play once:

Psychtoolbox/PsychDemos/DelayedSoundFeedbackDemo.m

@@ -1,5 +1,5 @@
-function DelayedSoundFeedbackDemo(reqlatency, duplex, freq, minLatency, device)
-% DelayedSoundFeedbackDemo([reqlatency=150 ms][, duplex=0][, freq]=48000[, minLatency=10 ms][, device])
+function DelayedSoundFeedbackDemo(reqlatency, duplex, freq, minLatency, device, channels)
+% DelayedSoundFeedbackDemo([reqlatency=150 ms][, duplex=0][, freq]=48000[, minLatency=10 ms][, device][, channels=2])
 %
 % CAUTION: TEST TIMING OF THIS SCRIPT WITH MEASUREMENT EQUIPMENT IF YOU
 % DEPEND ON ACCURATE FEEDBACK TIMING!!!
@@ -52,6 +52,8 @@ function DelayedSoundFeedbackDemo(reqlatency, duplex, freq, minLatency, device)
 %
 % 'device' Optional device index of soundcard to use.
 %
+% 'channels' Number of input and output channels to use. Defaults to 2.
+%
 % Specific tips for different setups:
 %
 % On OSX with builtin sound chip on Intel Macs, choose duplex = 0 for
@@ -159,13 +161,17 @@ function DelayedSoundFeedbackDemo(reqlatency, duplex, freq, minLatency, device)
 % fail with an error if it can't achieve the most high-perf settings:
 latmode = 4;
 
+if nargin < 6 || isempty(channels)
+    channels = 2;
+end
+
 if (reqlatency == 0) && duplex
     % Special case: Full-duplex mode with minimum latency. We bypass Matlab
     % by activating PsychPortAudios full-duplex monitoring mode. The driver
     % itself will feed back all captured sound to the outputs with lowest
     % possible latency. However we don't have any control over latency or
     % sound and this only works on full-duplex hardware...
-    pa = PsychPortAudio('Open', device, 4+2+1, latmode, freq, 2, [], minLatency);
+    pa = PsychPortAudio('Open', device, 4+2+1, latmode, freq, channels, [], minLatency);
 
     % Now that the device is open, try to enable the "Zero latency direct input
     % monitoring" feature of some subset of some sound cards.
@@ -239,12 +245,12 @@ function DelayedSoundFeedbackDemo(reqlatency, duplex, freq, minLatency, device)
 if ~duplex
     % Open the default audio device [], with mode 2 (== Only audio capture),
     % and a required latencyclass of latmode == low-latency mode, as well as
-    % a frequency of freq Hz and 2 sound channels for stereo capture.
+    % a frequency of freq Hz and 'channels' sound channels for stereo capture.
     % This returns a handle to the audio device:
-    painput = PsychPortAudio('Open', device, 2, latmode, freq, 2, [], minLatency);
+    painput = PsychPortAudio('Open', device, 2, latmode, freq, channels, [], minLatency);
 else
     % Same procedure, but open for full-duplex operation:
-    painput = PsychPortAudio('Open', device, 2+1, latmode, freq, 2, [], minLatency);
+    painput = PsychPortAudio('Open', device, 2+1, latmode, freq, channels, [], minLatency);
     % Output- and input device are the same...
     paoutput = painput;
 end
@@ -254,9 +260,8 @@ function DelayedSoundFeedbackDemo(reqlatency, duplex, freq, minLatency, device)
 PsychPortAudio('GetAudioData', painput, max(2 * lat, 10));
 
 if ~duplex
-    % Open default audio device [] for playback (mode 1), low latency (2), freq Hz,
-    % stereo output:
-    paoutput = PsychPortAudio('Open', device, 1, latmode, freq, 2, [], minLatency);
+    % Open default audio device [] for playback (mode 1), low latency (2), freq Hz output:
+    paoutput = PsychPortAudio('Open', device, 1, latmode, freq, channels, [], minLatency);
 end
 
 % Get actually chosen sampling frequency:
@@ -268,7 +273,7 @@ function DelayedSoundFeedbackDemo(reqlatency, duplex, freq, minLatency, device)
 % One could do this more clever, but this is a safe no-brainer and memory
 % is cheap:
 outbuffersize = floor(freq * 3 * max(lat, 10));
-PsychPortAudio('FillBuffer', paoutput, zeros(2, outbuffersize));
+PsychPortAudio('FillBuffer', paoutput, zeros(channels, outbuffersize));
 
 % Start audio playback immediately, wait for the start to happen. Retrieve the
 % start timestamp, ie., the system time when the first sample in the output
@@ -306,7 +311,7 @@ function DelayedSoundFeedbackDemo(reqlatency, duplex, freq, minLatency, device)
     fprintf('CaptureQuantum (Duty cycle length) is %f msecs, for a buffersize of %i samples.\n', captureQuantum * 1000, s.BufferSize);
 end
 
-[audiodata offset overflow capturestart] = PsychPortAudio('GetAudioData', painput, [], captureQuantum);
+[audiodata, offset, overflow, capturestart] = PsychPortAudio('GetAudioData', painput, [], captureQuantum);
 
 % Sanity check returned values: audiodata should be at least headroom * s.BufferSize
 % samples, offset should be zero as this is the first 'GetAudioData' call