[FFmpeg-devel] [RFC] h264 avoid starting decode on a non top field

[Michael Niedermayer]

On Sat, Nov 12, 2011 at 08:33:29PM +0100, madshi wrote:
> 2011/11/12 Joakim Plate <elupus at ecce.se>
> 
> > Soo0... anybody have h264 specs and can check what signals the first field
> > of a
> > field pair?
> >
> 
> I think the h264 spec is openly available? Anyway, what you're looking for
> is the field "pic_struct". Should be like this:
> 
> 0: progressive frame
> 1: top field only
> 2: bottom field only
> 3: interlaced frame, top field first
> 4: interlaced frame, bottom field first
> 5: interlaced frame, top field first + repeat first field
> 6: interlaced frame, bottom field first + repeat first field

There are 2 problems,
the syntax element this is in, is optional and not required.
this is about display, not decoding, SEIs are not required by a
conformant decoder.
"
     SEI messages assist in processes related to decoding, display or other purposes. However, SEI messages are not
     required for constructing the luma or chroma samples by the decoding process. Conforming decoders are not required to
     process this information for output order conformance to this Recommendation | International Standard (see Annex C
"


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