[FFmpeg-user] fieldmatch "marked as interlaced" -- doesn't work

Mark Filipak (ffmpeg) markfilipak at bog.us
Mon Mar 15 00:15:03 EET 2021

On 2021-03-14 10:47, Mark Filipak (ffmpeg) wrote:
> I hoped that "marked as interlaced" [1] meant that
> 'select=expr=not(eq(interlace_type\,TOPFIRST)+eq(interlace_type\,BOTTOMFIRST))' [2]

Have I made myself understood? Do you see the problem?

...progressive.&.scan-int.here... 'select' ...only.progressive.here...

But scan-interlace frames are getting through the 'select'.

1, 'select' is broken, or
2, 'fieldmatch' is broken, or
3, 'fieldmatch' is setting a different flag (not 'interlace_type').

How do I proceed?

> would work. However, the 'select' doesn't work. I'm counting on the 'select' working -- not working 
> is a complete show stopper.
> Is there some other species of "marked as interlaced" that will make the 'select' work?
> Thanks,
> Mark.
> [1] From https://ffmpeg.org/ffmpeg-filters.html#fieldmatch
> "The separation of the field matching and the decimation is notably
> motivated by the possibility of inserting a de-interlacing filter
> fallback between the two. If the source has mixed telecined and real
> interlaced content, fieldmatch will not be able to match fields for
> the interlaced parts. But these remaining combed frames will be
> *marked as interlaced*, and thus can be de-interlaced by a later
> filter such as yadif before decimation."
> [2] From https://ffmpeg.org/ffmpeg-filters.html#select_002c-aselect
> "interlace_type (video only)
> "    The frame interlace type. It can assume one of the following values:
> "        The frame is progressive (not interlaced).
> "        The frame is top-field-first.
> "        The frame is bottom-field-first."

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