[FFmpeg-devel] Question about PAFF decoding

Michael Niedermayer michaelni
Thu May 31 20:04:39 CEST 2007


On Thu, May 31, 2007 at 04:44:24PM +0200, Thorsten Jordan wrote:
> Hello,
> i have some questions, if they are too uninteresting for you, please
> ignore this mail. Sorry if i would waste your time.
> Maybe the student who implements PAFF decoding for h264 in SoC project
> would be willing to talk with me, but i dont' have his address.

there is no student who works on PAFF

> @Loren: if you want to give him mine i'd be happy: tjordan at macrosystem.de
> Here we go:
> with PAFF material a frame seems to be coded in two seperate fields,
> each with his own NAL start code (00 00 00 01 09 xx). I have seen two
> consecutive fields of one frame, first with xx=10, second xx=30, so
> first field has only I slices, the second P-slices. Other streams have
> 2x the 10 code. Bizarre...
> Would PAFF decoding work like decoding two consecutive frames with half
> height?


> Decoding would then need to handle double pitch value and fields have to
> be combined to a frame. Except that there are more references. Could the
> second field reference the first? It seems so because of the slice types
> announced (as i said above).
> Michael said several times that PAFF is hard to implement and that he
> feels sorry for the person who would try to implement it (or similar
> statement).
> Can you give me some examples what especially are the problems there?

read the h.264 spec


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Freedom in capitalist society always remains about the same as it was in
ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin
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