[FFmpeg-devel] H.264 + PAFF: BBC HD recording shows extreme interlacing artefacts

[Jeff Downs]

On Mon, 5 Nov 2007, Reinhard Nissl wrote:

> Attached you'll find an updated version of the earlier released
> top_field_first patches.
> 
> It derives top_field_first by comparing poc.

[...]

> Index: libavcodec/h264.c
> ===================================================================
> --- libavcodec/h264.c	(revision 10931)
> +++ libavcodec/h264.c	(working copy)
> @@ -7763,6 +7763,12 @@
>              *data_size = 0;
>  
>          } else {
> +            /*
> +             * Derive top_field_first from poc. Field pictures need to
> +             * be tested against bottom field poc as we enter here for
> +             * the second field.
> +             */
> +            cur->top_field_first = cur->poc == cur->field_poc[FIELD_PICTURE];
>              cur->interlaced_frame = FIELD_OR_MBAFF_PICTURE;
>  
>          //FIXME do something with unavailable reference frames

I'm not sure I understand this. cur->poc is the lesser of the two field 
pocs.

To me, when FIELD_PICTURE is true, the patch says:

top_field_first = MIN(top_poc, bottom_poc) == bottom_poc

or, more simply:

top_field_first = bottom_poc <= top_poc


Or do I miss something?

	-Jeff