[FFmpeg-devel] [PATCH] Provide top_field_first logic for h264.c

Michael Niedermayer michaelni
Fri Nov 9 18:49:04 CET 2007

On Fri, Nov 09, 2007 at 09:02:34AM +0000, M?ns Rullg?rd wrote:
> Michael Niedermayer <michaelni at gmx.at> writes:
> > Hi
> >
> > On Thu, Nov 08, 2007 at 09:22:16PM +0100, Reinhard Nissl wrote:
> >> Hi,
> >> 
> >> the patch was last posted in the thread "H.264 + PAFF: BBC HD recording
> >> shows extreme interlacing artefacts".
> >> 
> >> It provides top_field_first by comparing frame poc (picture order count)
> >> against top field poc. When both match, the frame shall be displayed
> >> with top field first.
> >
> > looks ok, except maybe that top_field_first would be 1 for non interlaced
> > content which is a little odd to me
> > i think (though havnt checked) that top_field_first is 0 for non interlaced
> > content in other codecs
> If the content is non-interlaced the fields should be displayed
> simultaneously, so there is no field order.  If the hardware isn't
> capable of this, the order chosen doesn't matter.  Hence there is no
> problem with setting it to top_field_first in this case.

mpeg 2 uses top field first for specifying field repeation together
with repeat first field (for progressive sequences)
we export this cleanly as repeat_pict but

i just thought it might be less confusing for applications if tff is set
consistently relative to the mpeg2 spec and repeat_pict

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

it is not once nor twice but times without number that the same ideas make
their appearance in the world. -- Aristotle
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