[Bug 71812] VDPAU: MPEG-4 ASP Garbling/Corruption

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=71812

--- Comment #13 from Fabrice Bellet <fabrice at bellet.info> ---
About this specific bug this time :)

I see a deterministic corruption in your sample too, that seems related to the
presence of sprite frames in the stream, and the result looks like these S
frames are just ignored by the hardware decoder (they are correctly passed to
the mesa level). 

For example, an effect of the corruption is the "C" of Captain, that is warped
into something that looks like the euro symbol (€), around 22.5s. Is it similar
to what you observe ? I can provide screenshot if needed.

I tried with VDPAU on radeonsi/uvd, with nouveau, and also with the proprietary
nvidia VDPAU implementation. _All_ implementations have this problem. The
radeon and the nvidia driver just silently drop S frames, and the following
non-S frames are corrupted. The nouveau driver replaces S frame by something
that looks like the rendering of an unintialized vmem buffer.

Also, I can reproduce the _same_ corruption with the ffmpeg software mpeg4
decoder, just by disabling the S-frames handling with this patch:

diff -uNrp ffmpeg-2.1.5.orig/libavcodec/mpeg4videodec.c
ffmpeg-2.1.5/libavcodec/mpeg4videodec.c
--- ffmpeg-2.1.5.orig/libavcodec/mpeg4videodec.c    2014-07-21
20:43:58.550548835 +0200
+++ ffmpeg-2.1.5/libavcodec/mpeg4videodec.c    2014-07-21 20:43:11.632103072
+0200
@@ -2105,6 +2105,8 @@ static int decode_vop_header(MpegEncCont
      }

      if(s->pict_type == AV_PICTURE_TYPE_S &&
(s->vol_sprite_usage==STATIC_SPRITE || s->vol_sprite_usage==GMC_SPRITE)){
+         printf("S frame\n");
+         return AVERROR_INVALIDDATA;
          if (mpeg4_decode_sprite_trajectory(s, gb) < 0)
              return AVERROR_INVALIDDATA;
          if(s->sprite_brightness_change) av_log(s->avctx, AV_LOG_ERROR,
"sprite_brightness_change not supported\n");

Are sprite frames supposed to be decoded by the hardware ? The radeon driver
has a sprite-related section in its ruvd_mpeg4 struct definition in
mesa/src/gallium/drivers/radeon/radeon_uvd.h.

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