[Ffmpeg-devel] Re: Re: Re: mjpeg with trellis quant segaults ... to be expected

Michael Niedermayer michaelni
Thu Oct 26 19:48:39 CEST 2006


On Thu, Oct 26, 2006 at 07:23:44PM +0200, Karl H. Beckers wrote:
> > the indention of the new code is wrong, the patch has random linebreaks
> > in the midde (=its malformed and not applyable)
> > besides checking for this in the innermost loop is not acceptable
> > this can and should be checked during init or trellis quant should be
> > changed to support mjpeg
> Michael,
> I only sent the diff to highlight the issue not to suggest that this
> should be the fix or applied as a patch. I'm also all with you about
> adding the feature (though that won't be me ;S), 

why not? its not that hard, first just fill the length array with the
correct vlc lengths see  mjpeg.c:encode_block() then ensure that the
assumed dequantization and assumed number of bits in trellis_quant
is correct ...

> but then, if the encoders
> are not required to put a value there (or perhaps they are and mjpeg just
> doesn't comply) the code shouldn't rely on it being filled.
> Anyway, perhaps the attached bit is more agreeable as a quickfix.

no, dct_quantize_trellis_c() should never be called if the length arrays
arent initalized

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is

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