[FFmpeg-trac] #11357(avcodec:closed): Inconsistent when decoding an H.264 bitstream with bi-prediction weighted prediction enabled on ARM and x86 devices

[FFmpeg]

#11357: Inconsistent when decoding an H.264 bitstream with bi-prediction weighted
prediction enabled on ARM and x86 devices
-------------------------------------+-------------------------------------
             Reporter:  Bin Peng     |                    Owner:  Michael
                                     |  Niedermayer <michael@…>
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:  avcodec
              Version:  git-master   |               Resolution:  fixed
             Keywords:  H264         |               Blocked By:
  decoder arm                        |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Changes (by Michael Niedermayer <michael@…>):

 * owner:  (none) => Michael Niedermayer <michael@…>
 * resolution:   => fixed
 * status:  new => closed

Comment:

 In [changeset:"74fd2c3ddbaf1fef5c4777784aa72b5747ad389c/ffmpeg"
 74fd2c3d/ffmpeg]:
 {{{#!CommitTicketReference repository="ffmpeg"
 revision="74fd2c3ddbaf1fef5c4777784aa72b5747ad389c"
 avcodec/h264_mb: Fix tmp_cr for arm

 When decoding a bitstream with weighted-bipred enabled,
 the results on ARM and x86 platforms may differ.

 The reason for the inconsistency is that the value of
 STRIDE_ALIGN differs between platforms. And STRIDE_ALIGN
 is set to the buffer stride of temporary buffers for U
 and V components in mc_part_weighted.

 If the buffer stride is 32 or 64 (as on x86 platforms),
 the U and V pixels can be interleaved row by row without
 overlapping, resulting in correct output.
 However, on ARM platforms where the stride is 16,
 the V component did overwrite part of the U component's pixels,
 leading to incorrect predicted pixels.

 The bug can be reproduced by the following bitstream.

 https://trac.ffmpeg.org/attachment/ticket/11357/inter_weighted_bipred2.264

 Fixes: ticket 11357
 Commit-msg-mostly-by: Bin Peng <pengbin at visionular.com>
 Reviewed-by: Bin Peng <pengbin at visionular.com>
 Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/11357#comment:8>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker