[FFmpeg-devel] [PATCH] Fix nonsense MPEG-4 hwaccel code.

Reimar Döffinger Reimar.Doeffinger at gmx.de
Sun Sep 22 16:22:12 CEST 2013

On Thu, Sep 19, 2013 at 07:23:31PM +0200, Reimar Döffinger wrote:
> Issues with the code:
> 1) The skip_bits_long breaks packed B-frames since we skip
> of the packed frame, even for VDPAU.
> 2) Calling ff_h263_find_resync_marker_reverse is nonsense for MPEG-4,
> and for H.263 the only code using this (vaapi_mpeg4) explicitly reverts
> this change!
> 3) mb_x/mb_y are always 0 when vaapi_mpeg4_decode_slice, so doing
> computations with them is just obfuscation
> 4) due to not updating mb_y the code would always go into the error
> resilience case, causing nonsense error messages and maybe further
> issues.
> While tested to fix the data provided to the decoder in case of
> VDPAU so it is the same as for the non-hwaccel code, the VA-API code
> was not tested to still work, and adding regression testing even
> as a quick hack is much more complicated for it.


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