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#129 Loud pop at end of pregap

open
nobody
None
5
2004-05-15
2004-05-15
David A. Gatwood
No

I'm trying to use cdrdao (1.1.7) on a FreeBSD box with a TDK
CDRW4800B burner. When I try to burn, for each of my tracks I'm
getting this bogus error message:

WARNING: Length of track "foo.aiff" is not a multiple of sample
size (4).

about twelve or thirteen times---one per audio file.

Of course, it is technically correct. The ls -l length of the file isn't
a multiple of 4. However, the AIFF file format does not guarantee
the above constraint to be true. The chunk headers are not
generally multiples of 4, thus the file must be parsed in order to
know the actual length of the sound.

These files were written by BIAS Peak, one of the most popular
Mac audio editing programs. It plays correctly with no warnings,
pops, or glitches in dozens of pieces of software, and burns
correctly with iTunes. I have no reason to believe that the tracks
are anything other than valid AIFF files....

The problem comes when I move the file to the FreeBSD box to
burn. The CD burns mostly correctly. I can play it in various
players. However, at the start of each track, there is a -loud- pop.
We're not talking about a "sound suddenly goes to zero" pop. More
like a "sound suddenly goes from 0 to 255" pop.

Note that the audio files are faded to zero at both ends, so the
zeroed pregap should not cause any audible pop. Thus, either the
pregap isn't being zeroed completely or there's something going
wrong with the first few samples of audio data.

If I change tracks on playback, I get the pop immediately upon
starting the new track. I also hear the pop if I play through the
pregap. This suggests that the problem is probably not the pregap,
but rather an unexpected high value shoved into the first sample.

If I have to, I'll use sox to convert them all to WAV files, but the
AIFF processing really should be fixed. :-)

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