[FFmpeg-devel] Question about PAFF decoding

Thorsten Jordan tjordan
Thu May 31 16:44:24 CEST 2007


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.

@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

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

Can you give me some examples what especially are the problems there?

Best Regards, Thorsten

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