[FFmpeg-devel] PAFF support h264 - preliminary patch as notes
Tue Jul 17 02:31:13 CEST 2007
On Tue, Jul 17, 2007 at 09:24:19AM +1000, Neil Brown wrote:
> - Combine fields into frames. I really don't know what the desired
> result is here. The decoding process will produce a series of
> interlace fields, first a top field (lines 0,2,4,6,...) then a
> bottom field (lines 1,3,5,7,...). How should these be presented
> to the application?
> One option is to combine them into a single field. However this
> loses information as the fields should be separated by 1/50th of a
> second (for the PAL case).
> The other option would be to pass them back as individual fields
> with half the expected number of lines and tell the application
> that they are fields to be interlaced together. However I have no
> idea how to do that or if it is even possible.
> If the first option is best, then we need to hold on to the first
> field until the second field is ready. Then merge them together.
> If the second option is best (which I suspect to be the case), then
> we need to decode fields densely (not leaving blank lines between
> content lines, only using the top half of the buffer), which means
> that my following patch is completely wrong as it gets the
> decoding to use the full height, but only half the lines.
> It would also mean that if we find a FRAME picture while expecting
> interlacing, we need to split it into the two component frames to
> return it to the application. I think this would be a very
> substantial code change. It might make the code cleaner though.
> I don't know if/when I might find time to work on this again so I am
> doing this brain dump now in case it might help someone else. I would
> really like input on the question of how to return interlaced video
> fields before I even consider hacking on the code any more.
PAFF fields should be returned like MBAFF, that is 2 fields interleaved
into 1 frame
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato
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