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

FFmpeg trac at avcodec.org
Mon Dec 8 23:23:52 CET 2014

#4168: defect : mpeg2 interlaced yuv420 chroma incorrectly decoded
             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

Comment (by clam):

 Replying to [comment:9 kierank]:
 > Replying to [comment:8 cehoyos]:
 > > Replying to [comment:4 clam]:
 > > > Looks like the interlacing information is lost somewhere between
 libavcodec and libswscale.
 > >
 > > I don't think this "information" exists at all: The interlaced flag in
 MPEG streams just tells you if the encoder was set to "interlaced" not if
 the content actually is interlaced.
 > The DVB encoder should still perform an interlaced chroma downconversion
 irrespective of the content type (because the DVB encoder doesn't know

 Yes the actual content (interlaced/progressive) is irrelevant. The
 interlaced flag only indicates that the chroma is shared by two other
 lines (odd/odd or even/even) and not two consecutive lines (odd/even).

 Progressive 4:2:0 chroma is a better choice for progressive content but
 when you mix interlaced & progressive source, interlaced 4:2:0 chroma is
 an easier choice since it's compatible with both.

Ticket URL: <https://trac.ffmpeg.org/ticket/4168#comment:11>
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