[FFmpeg-devel] [PATCH] Implement PAFF in H.264

[Jeff Downs]

On Thu, 20 Sep 2007, Martin Zlomek wrote:

> The attached patch fixes picNumX in "Adaptive memory control
> decoded reference picture marking process".
> 

> --- h264.c.orig	2007-09-20 23:30:38.000000000 +0200
> +++ h264.c	2007-09-20 23:31:42.000000000 +0200
> @@ -3644,7 +3644,7 @@
>  
>                  h->mmco[i].opcode= opcode;
>                  if(opcode==MMCO_SHORT2UNUSED || opcode==MMCO_SHORT2LONG){
> -                    h->mmco[i].short_pic_num= h->curr_pic_num - get_ue_golomb(gb) - 1;
> +                    h->mmco[i].short_pic_num= (h->curr_pic_num - get_ue_golomb(gb) - 1) & (h->max_pic_num - 1);
>  /*                    if(h->mmco[i].short_frame_num >= h->short_ref_count || h->short_ref[ h->mmco[i].short_frame_num ] == NULL){
>                          av_log(s->avctx, AV_LOG_ERROR, "illegal short ref in memory management control operation %d\n", mmco);
>                          return -1;

Why?  I'm having trouble mapping this to anything in the spec. Compliant 
streams should contain data that produces a valid short_pic_num here.  
Non-compliant streams might produce a garbage pic num that is beyond 
maximum pic num, but that'll just cause the MMCO execution to skip this 
operation because it can't find a picture with that picture number.

	-Jeff