Basic test and demo of the sound recording/capture functionality of the
new PsychSound() function.
Parameters: duration = Recordingcapacity (in seconds) of the sound capture
buffer. After recording of sound has been started, PsychSound will
perform continuous recording into an internal ring-buffer with a storage capacity
of ‘duration’ seconds, until recording gets stopped again. Soundrecording
is done asynchronously as an automatic background process, independent of
Matlabs/Psychtoolboxs execution. This way you can continue execution of
your Matlab script (sound output, response collection, visual output,
…) while PsychSound is recording in the background. You can query the
amount of new recorded sound data in the buffer and you can fetch this
data from the buffer into a Matlab matrix at any time during of after
recording. Be aware though that if the buffers capacity is exhausted, it
will dispose old sound data to store new one - only the last ‘duration’
seconds of the most recently recorded sound are kept.
This leaves you with two options:
a) Request a buffer big enough to store the full duration of your
recording from Start of capture until the end, and read out the recorded
data into a Matlab matrix after the end of the recording. This is the
most easy to implement (nice linear control flow Start->Stop->Fetch), but
you have to know the maximum duration in advance, and you’ll potentially
use up significant amounts of memory.
b) Request a buffer big enough to hold sound data for at least the
duration of one iteration of your trial loop. During each iteration, poll
and fetch portions of the recording into your Matlab matrix. More
involved programming, but low memory consumption.
With b) you can obviously also implement an audio recorder for infinite
capture into a file via while(1) Waitabit; Poll&Fetch bit of sound data
from PsychSound into Matrix; Append content of matrix to a file; end;
And you can do live capture, manipulation & analysis of sound, e.g.,
voice triggers, feedback of recorded sound to sound output and such.