[Flac-dev] ERROR: mismatch in decoded data, verify FAILED!

Josh Coalson
Fri, 10 Sep 2004 16:45:27 -0000

> > There have been reports of -9 using huge amounts of memory.  -9 is
> > really
> > theoretical, but people always seem to want to try the max setting.
> >  Anyway,
> > that's not an excuse but figuring out why -9 is using so much
> > memory is lower
> > on my list than other stuff.  -8 should get within 0.01% of -9 and
> > is pretty
> > reliable.
>
> I am able to reliably reproduce the -9 memory problem with one of my
> WAV files.
> I split it in two repeatedly, doing a binary search to find the
> smallest chunk
> that would trigger the problem, and I got it down to 28224 samples
> (this is a
> 44.1/16bit/stereo file, so about 0.5 seconds).  I have put the file
> up at
> <http://people.debian.org/~mdz/flac-test-case-1.wav>.  Here is a gdb
> backtrace
> at the point where it is allocating gobs of memory:

I think I see the problem just from the trace but I will
grab the file and check it out.

> Also, Kai has been kind enough to send me a copy of his file which
> has a
> problem only on -8, which I'll be looking into soon.

Matt, if you whittle this file down can you make it
available also?

One more thing I forgot to mention about debugging.  The
first point of suspicion is the assembly in the decoder.
That you can try with 'configure --disable-asm-optimizations'
The second is arithmetic overflow in the linear predictor.
You can test that by 'configure --enable-debug' which does
overflow checking.