[FFmpeg-trac] #388(undetermined:closed): Bug with deinterlacing!
FFmpeg
trac at avcodec.org
Mon Aug 15 19:04:15 CEST 2011
#388: Bug with deinterlacing!
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Reporter: Silent Rain | Owner: michael
Type: defect | Status: closed
Priority: normal | Component: undetermined
Version: unspecified | Resolution: worksforme
Keywords: | Blocked By:
Blocking: | Reproduced: 0
Analyzed: 0 |
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Changes (by cehoyos):
* status: open => closed
* resolution: => worksforme
Comment:
(ffmpeg command line and console output is still missing making this an
invalid ticket.)
While the content of your sample may be interlaced (I agree it is), the
stream is encoded as progressive frames, afaict, so how should FFmpeg be
able to know the stream is interlaced?
Note that the 25fps progressive material that TV stations broadcast here
via DVB is encoded as interlaced frames "50i" (50 fields per second, so
every sane decoder delivers 25 progressive frames per second), so FFmpeg -
semantically incorrectly - sets interlaced_frame. Generally, afaict, you
have to visually inspect the material to decide if it is interlaced or
not.
Or in other words: You can take interlaced source material and encode it
as progressive frames (try ffmpeg -i interlaced_file -qscale 2 to get a
sample with maximum quality and still interlaced frames that yadif and
vdpau deinterlace fine), so all flags in the stream show "progressive" as
in your sample, or you can take progressive, 25fps material (or claim that
24fps material is actually 25fps) and "pull it up" to 50 fields per
seconds, then encode it interlaced (with the respective fields set) as it
is done in case of DVB broadcast of films here, but if you use a de-
interlacer after decoding, you (may) worsen the picture quality; without a
de-interlacer, you get exactly the original 25 fps progressive material
(wrongly assuming a lossless encoder).
If you wanted to open a feature request for a video filter that reports if
material is interlaced or not, please reword the ticket.
--
Ticket URL: <https://avcodec.org/trac/ffmpeg/ticket/388#comment:3>
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