Try to support invalid h264 that does not mark IDR with POC=0.

Fixes issue576.

Originally committed as revision 15153 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h264.c

@@ -7488,7 +7488,7 @@ static int decode_frame(AVCodecContext *avctx,
 //FIXME factorize this with the output code below
         out = h->delayed_pic[0];
         out_idx = 0;
-        for(i=1; h->delayed_pic[i] && h->delayed_pic[i]->poc; i++)
+        for(i=1; h->delayed_pic[i] && (h->delayed_pic[i]->poc && !h->delayed_pic[i]->key_frame); i++)
             if(h->delayed_pic[i]->poc < out->poc){
                 out = h->delayed_pic[i];
                 out_idx = i;
@@ -7632,12 +7632,12 @@ static int decode_frame(AVCodecContext *avctx,
 
             out = h->delayed_pic[0];
             out_idx = 0;
-            for(i=1; h->delayed_pic[i] && h->delayed_pic[i]->poc; i++)
+            for(i=1; h->delayed_pic[i] && (h->delayed_pic[i]->poc && !h->delayed_pic[i]->key_frame); i++)
                 if(h->delayed_pic[i]->poc < out->poc){
                     out = h->delayed_pic[i];
                     out_idx = i;
                 }
-            cross_idr = !h->delayed_pic[0]->poc || !!h->delayed_pic[i];
+            cross_idr = !h->delayed_pic[0]->poc || !!h->delayed_pic[i] || h->delayed_pic[0]->key_frame;
 
             out_of_order = !cross_idr && out->poc < h->outputed_poc;