afWriteFrames man page
afWriteFrames — write sample frames to a track in an audio file
AFframecount afWriteFrames(AFfilehandle file, int track, const void *data, AFframecount count);
afWriteFrames attempts to write up to count frames of audio data from the buffer data to the audio file handle file.
file is a valid file handle returned by afOpenFile(3).
track is always AF_DEFAULT_TRACK for all currently supported file formats.
data is a buffer of sample frames to be written to the file.
count is the number of sample frames to be written.
afWriteFrames returns the number of sample frames successfully written to file.
afWriteFrames can produce these errors:
the file handle was invalid
the track is not AF_DEFAULT_TRACK
writing audio data to the file failed
seeking within the file failed
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