ExtAudioFileWrite writes zeroes?
ExtAudioFileWrite writes zeroes?
- Subject: ExtAudioFileWrite writes zeroes?
- From: patrick machielse <email@hidden>
- Date: Thu, 28 Jun 2007 01:30:18 +0200
I have an application which processes audio files and uses the
ExtendedAudioFile API to write the processed data to file. The
processing is done in several steps. In each step I set up an AUGraph
which starts with an AudioFilePlayerAU, followed by a number of other
units and ending in a Generic Output unit. Saving is done on a render
notification callback installed on the output unit. All processing is
done offline.
In the last processing step I have a very short AUGraph; a file
player, 1 audio unit, and a generic output unit. The input file
format is CAF, and the output format is WAV. All the calls to
ExtAudioFileWrite() succeed, and the file length is exactly as long
as it should be, but regularly a large part of the file is just
zeroes. Just before this happens there are mostly a few 'white outs'.
I have similar (but longer...) AUGraph that reads mp3 (mostly) and
writes out CAF files without any problems. I looks as if
simultaneously reading in and writing out large audio files somehow
goes wrong.
I've tried to increase the io buffer to 1 MB (from the default value
of 64k) but this hasn't improved the situation. Should I use a larger
buffer still? Should I try to write the file asynchronously?
patrick
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