[FFmpeg-trac] #5732(avcodec:open): Display corruption on very high-bitrate H.264 files

FFmpeg trac at avcodec.org
Sun Jul 24 21:42:11 EEST 2016

#5732: Display corruption on very high-bitrate H.264 files
             Reporter:  Sesse       |                    Owner:
                 Type:  defect      |                   Status:  open
             Priority:  minor       |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:  h264        |               Blocked By:
             Blocking:              |  Reproduced by developer:  1
Analyzed by developer:  0           |

Comment (by Sesse):

 Let's see. I can't do any more tests easily, unfortunately; this was part
 of a rig for an event, and I don't have access to comparable hardware to
 produce the input signal anymore. It might very well be that the QSV-
 generated stream is somehow out-of-spec here; as a layperson, it's
 impossible for me to say. As for i965-va-driver versions, we stopped
 upgrading stuff a few months before the event; just locked the versions of
 everything and tested it intensely to avoid nasty surprises from new
 versions. :-) I see from a backup that we used version 1.7.0; looks like
 1.7.1 is the latest, but at least it's not stone age.

 I ran your decode command-line. I couldn't really play out.nut in
 anything, it looks more like a still image to me. But I've uploaded it to
 http://storage.sesse.net/out.nut in case you can get something usable out
 of it.

 As for x264's performance on this clip, Nageru makes one in parallel to
 the QSV stream. (The QSV stream is meant for archival, the x264 stream is
 meant for direct consumption by clients.) At 5 Mbit/sec on a 4x3.6 GHz
 Haswell (we run with speedcontrol, which on this machine largely means
 hovering around somewhere between the equivalent of “slow” and “slower”
 presets), it was much better than the YouTube version
 (https://www.youtube.com/watch?v=-N5CLcSkkWs), but far from perfect. I
 would say x264 did a respectable job, but not a fantastic one.

Ticket URL: <https://trac.ffmpeg.org/ticket/5732#comment:13>
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