[FFmpeg-trac] #9573(avcodec:new): libx264 ignores color range flag for gray10 input

FFmpeg trac at avcodec.org
Wed Dec 29 17:13:11 EET 2021


#9573: libx264 ignores color range flag for gray10 input
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             Reporter:  Diederick    |                    Owner:  (none)
  Niehorster                         |
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  libx264      |               Blocked By:
  gray10                             |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by Diederick Niehorster):

 Replying to [comment:5 Balling]:
 > This is a duplicate of that issue about gray being always full range, it
 was a fix in ffmpeg actually. See my closing comment there
 https://trac.ffmpeg.org/ticket/2452#comment:20

 I do not see how it is a duplicate. Here a source is actually full range,
 but treated as limited range by the encoder regardless.
 Note that it appears without using ffmpeg, also when i directly use the
 API (which is how i came across it).

 I have an input that is actually full-range, and identified as such in the
 AVFrame. Full range is set also in the encoder context. Yet luminance is
 shifted down. To be fair, i do not know if this in the libx264 encoder, or
 in the h264 decoder which i have to use to read the file back in. But with
 ffv1 stored in an mkv i can do lossless roundtrip with ffmpeg and with the
 API, suggesting its something specific to libx264/h264. Note also that
 ffprobe does recognize the stream as full range (see output in problem
 report).
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9573#comment:6>
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