flac dev - Sep 2004 - Re: Bug#119396: flac: Decoded data does not equal orginal data.

retitle 119396 flac: problems encoding very small files
thanks

flac-dev: I received the following bug report from a Debian user.  Please
preserve Cc: 119396-forwarded@bugs.debian.org when replying.

On Mon, Nov 12, 2001 at 05:44:09PM -0800, Adam M. Costello wrote:
> Package: flac
> Version: 1.0-3
> Severity: grave
> 
> The file "test" is a 1000-byte raw audio file (44100 samples per
second,
> 16-bit signed, native byte order (little-endian), 2 channels).
> 
> flac -fl -fc 2 -fp 16 -fs 44100 test
> flac -d -fl -fc 2 -fp 16 -fs 44100 -o test-out test.flac
> 
> test-out ought to be identical to test, but test-out is 12 bytes longer.
> The first 12 bytes are repeated.  If the first 12 bytes of test-out are
> removed, then the two files will agree.
>
> -- System Information
> Debian Release: testing/unstable
> Kernel Version: Linux arwen 2.4.13 #2 SMP Fri Nov 9 04:29:32 GMT 2001 i686
unknown
> 
> Versions of the packages flac depends on:
> ii  libc6          2.2.4-3        GNU C Library: Shared libraries and
Timezone
> ii  libflac1       1.0-3          Free Lossless Audio Codec - runtime
library
Adding -V to the command line gives this:

flac -V -fl -fc 2 -fp 16 -fs 44100 test
[...]
options: -P 0 -b 4608 -m -l 8 -q 0 -r 3,3 -R 0 -V
test: 101% complete, ratio=0.078

Which is clearly wrong (101%), and I think should probably trigger an error
(but doesn't).  Based on a few quick tests, this kind of problem seems to
occur with any file smaller than 4k (at least when using
44100Hz/16bps/2chan).

-- 
 - mdz

Matt Zimmerman <mdz@debian.org> wrote:
> Based on a few quick tests, this kind of problem seems to occur with
> any file smaller than 4k (at least when using 44100Hz/16bps/2chan).
I don't think the problem is related to file size.  The exact same
thing happens when I use a file over 700 MB.  That's actually where I
discovered the problem, then I tried a small file to see if the behavior
was consistent.

AMC

retitle 119396 flac: Decoded raw data does not match original raw data
thanks

On Tue, Nov 13, 2001 at 02:38:32AM +0000, Adam M. Costello wrote:
> Matt Zimmerman <mdz@debian.org> wrote:
> 
> > Based on a few quick tests, this kind of problem seems to occur with
> > any file smaller than 4k (at least when using 44100Hz/16bps/2chan).
> 
> I don't think the problem is related to file size.  The exact same
> thing happens when I use a file over 700 MB.  That's actually where I
> discovered the problem, then I tried a small file to see if the behavior
> was consistent.
You are right; my test was flawed.  However, it doesn't happen exactly the
same for me.  I seem to get 56 extra bytes, not 12.

-- 
 - mdz