[Ffmpeg-devel] interlace field order
Tue Feb 21 10:35:48 CET 2006
2006/2/21, M?ns Rullg?rd <mru at inprovide.com>:
> Dieter <freebsd at sopwith.solgatos.com> writes:
> > After googling a bit, I find that:
> > Mpeg can be either top-field-first or bottom-field-first.
> > DV is always bottom-field first.
> > When converting mpeg to DV, ffmpeg sometimes outputs the wrong
> > field order.
> > So the question is: how can we detirmine when the field order needs
> > to be corrected?
> > In libavcodec/mpeg12.c mpeg_decode_picture_coding_extension()
> > I turned on the printf for top_field_first. Some files have
> > top_field_first all 0, some have it all 1, and some have
> > *interesting* changes, like being 1 for awhile, then changing
> > to an alternating pattern, with 1, 2 and 3 samples:
> Some form of telecine, most likely.
Yes, when picture_structure is FRAME then top_filed_first and
repeat_first_field are used for telecine.
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