[Ffmpeg-devel] interlace field order

[Måns Rullgård]

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.

-- 
M?ns Rullg?rd
mru at inprovide.com