[FFmpeg-trac] #4168(undetermined:new): defect : mpeg2 interlaced yuv420 chroma incorrectly decoded

[FFmpeg]

#4168: defect : mpeg2 interlaced yuv420 chroma incorrectly decoded
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             Reporter:  clam         |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
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Comment (by DonMoir):

 Using ffmpeg_chromabug.mpg as a test case, this is not a bug in the
 decoding as the title of the ticket implies. It decodes fine, and the
 frames interlaced_frame flag is set to 1. It is up to you at this point to
 deinterlace or not and you would need to do it before calling into
 libswscale. libswscale has no notion of it.

 It is probably such that the command line tools will not do it
 automatically.

 You mentioned you may want to do something about it in your own code and
 this is what I do. I have since pulled the deinterlacing into my own code
 and use that and don't depend on ffmpeg for that. One problem is the
 interlace_flag does not contain the type of deinterlacing that should be
 performed. In all samples that I have and all that I have been able to
 find, a simple deinterlace such as avpicture_deinterlace works fine. It
 also works perfect for above sample. It is recommended you use avfilter
 and yadif for this now, but that can be way more overhead then you need. I
 do not use avfilter for anything.

 So if you are using ffmpeg_chromabug.mpg as a sample to point to how this
 is a bug, then that is incorrect. It displays perfect for me using the
 following.

 decode->deinterlace->scale not decode->scale

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Ticket URL: <https://trac.ffmpeg.org/ticket/4168#comment:26>
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