[FFmpeg-trac] #6717(undetermined:new): h264 - gray chroma - error while decoding - left block unavailable

FFmpeg trac at avcodec.org
Sat Dec 2 11:19:56 EET 2017

#6717: h264 - gray chroma - error while decoding - left block unavailable
             Reporter:  latot        |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0

Comment (by KTSamy):

 Replying to [comment:14 cehoyos]:
 > Please explain how - exactly! - I can produce such a file.

 The method I have mentioned can produce the file with a similar(?) issue.
 But, it will play with ffplay as usual if you start from the beginning.
 But if you pass seek parameter, you will see ffplay will won't properly &
 can see the similar errors.

 Just encode as I have mentioned & try the following

 ffplay -ss 5 out.ext

 Note: Older ffplay versions (at least 3.2.4) are working fine. But, all
 3.3 & 3.4 versions will have the issues in playing the videos that was
 encoded with 8x8dct enabled. Videos encoded with ffmpeg wich has newer
 x264 encoder will not produce such files as they force disables 8x8dct
 when you encode to a video with 4:4:4 Chroma subsampling.

Ticket URL: <https://trac.ffmpeg.org/ticket/6717#comment:15>
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