[FFmpeg-devel] [PATCH] raw_read_header fix

Michael Niedermayer michaelni
Sat Jul 14 13:41:03 CEST 2007


On Sat, Jul 14, 2007 at 01:37:02PM +0200, Alex Beregszaszi wrote:
> Hi,
> > > > > pcm.diff adds checks into pcm.c to bail out when no sampling rate or
> > > > > channels are set, as itself cannot fill those fields out.
> > > > 
> > > > but decoding of pcm as well as alaw/ulaw should work fine without a sample
> > > > rate, so its wrong to fail ...
> > > 
> > > Why is it wrong? What can you do with it without knowing the settings?
> > 
> > well you can convert alaw<->pcm for example witout knowing the samplerate
> You can, but still the output wont contain any headers. Are we supposed
> to do blind conversions? This is the same as if you would pass RGB data
> as YUV to the MPEG2 encoder and say it is the way it should. Surely it
> can be done, and you will get some output afterwards decoding, but still
> not the thing we call "valid".

raw pcm <-> raw alaw will not be any different with sampling rate than without

> > > > nonsense, theres nothing invalid on an AVRational if these are false
> > > 
> > > Okay than av_rescale_q/rnd must be fixed to avoid crash with den=0.
> > 
> > no, i disagree, av_rescale rescales an integer, that cant work with den=0
> > still this doesnt make x/0 invalid, its not a real number and calculations
> > with it wont follow all the rules of a field but still handling it
> > sanely (like most FPUs) makes sense IMHO
> Sure, but can you concentrate on the initial question? Can you fix this
> issue in a way you prefer? Running seektest on ulaw/alaw (which is
> enabled by default) causes division by zero.

yes i can fix it but i wont, iam too lazy, i just review patches ...
and the ones posted didnt look good


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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