[FFmpeg-devel] [PATCH]lavc/h264:Only check x264_build if it was set

Hendrik Leppkes h.leppkes at gmail.com
Fri Oct 6 20:23:58 EEST 2017

On Fri, Oct 6, 2017 at 6:54 PM, Henrik Gramner <henrik at gramner.com> wrote:
> On Thu, Oct 5, 2017 at 8:31 AM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>> Hi!
>> Attached patch fixes ticket #6717.
>> Please comment, Carl Eugen
> Signed numbers are converted to unsigned when compared to unsigned
> numbers which means -1 becomes UINT_MAX so this patch shouldn't
> actually change anything.
> #6717 is probably unfixable without breaking something else. Old x264
> versions produced non-spec-compliant output in the case of 4:4:4 +
> cabac + 8x8dct, and old libavcodec versions had the same bug on the
> decoder side which is now fixed to handle spec-compliant files.
> libavcodec supports decoding older broken files when it detects them
> in order to avoid breaking backwards-compatibility, but they can't be
> detected as such if someone removed the x264 SEI.
> tl;dr; #6717 is one of the reasons why messing with SEI messages is
> generally a bad idea unless you know what you're doing.

Its unfortunate that the CABAC change causes entire bitstream destruction.

I don't suppose its in any way feasible to somehow detect the
difference somehow, or re-try if it failed?

- Hendrik

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