[FFmpeg-devel] [PATCH] PB-frames support for i263

[Kostya]

On Tue, Feb 17, 2009 at 06:48:57PM +0100, Michael Niedermayer wrote:
> On Tue, Feb 17, 2009 at 08:29:36PM +0200, Kostya wrote:
[..]
> > separated
> > Since i263 are the only codec known (to me) to contain PB-frames, it's the
> > only way to test code.
> 
> huh? ITU h263+ allows PB frames, and id be surprised if there are no reference
> streams around ...

I'd like to find them too.

[skipping B-part of PB-frame in ff_h263_decode_mb()]
> 
> the code above that alraedy was there also can be factored out
> also s->mb_intra = 0; can always be done before and the one afterwards
> is just restoring the overwritten mode i suspect

It is. The problem is factoring out that code - PB-frame P-part may contain
both intra- and interblocks, and B-part stuff is dispersed between them
(i.e. own CBP before P-part CBP, motion vectors after P-part motion vectors,
own block data after I- or P-block data).

[PB-frame support in I263]
> i dont think that will compile without the other patch and the other
> patch will not work without that
> aka poorly split
 
What about this patch for better parsing of i263 frame header?
 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
-------------- next part --------------
Index: libavcodec/h263.c
===================================================================
--- libavcodec/h263.c	(revision 16921)
+++ libavcodec/h263.c	(working copy)
@@ -6185,17 +6232,54 @@
         return -1;      /* SAC: off */
     }
     s->obmc= get_bits1(&s->gb);
-    if (get_bits1(&s->gb) != 0) {
-        av_log(s->avctx, AV_LOG_ERROR, "PB frame mode no supported\n");
-        return -1;      /* PB frame mode */
+    s->pb_frame = get_bits1(&s->gb);
+
+    if(format == 7){
+        format = get_bits(&s->gb, 3);
+        if(format == 0 || format == 7){
+            av_log(s->avctx, AV_LOG_ERROR, "Wrong Intel H263 format\n");
+            return -1;
+        }
+        if(get_bits(&s->gb, 2)){
+            av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
+            return -1;
+        }
+        s->loop_filter = get_bits1(&s->gb);
+        if(get_bits1(&s->gb)){
+            av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
+            return -1;
+        }
+        if(get_bits1(&s->gb))
+            s->pb_frame = 2;
+        if(get_bits(&s->gb, 5)){
+            av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
+            return -1;
+        }
+        if(get_bits(&s->gb, 5) != 1){
+            av_log(s->avctx, AV_LOG_ERROR, "Invalid marker\n");
+            return -1;
+        }
     }
+    if(format == 6){
+        int ar = get_bits(&s->gb, 4);
+        skip_bits(&s->gb, 9); // display width
+        if(!get_bits1(&s->gb))
+            return -1;
+        skip_bits(&s->gb, 9); // display height
+        if(ar == 15){
+            skip_bits(&s->gb, 8); // aspect ratio - width
+            skip_bits(&s->gb, 8); // aspect ratio - height
+        }
+    }
 
-    /* skip unknown header garbage */
-    skip_bits(&s->gb, 41);
-
     s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
     skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
 
+    if(s->pb_frame){
+        skip_bits(&s->gb, 3); //temporal reference for B-frame
+        skip_bits(&s->gb, 2); //dbquant
+    }
+
     /* PEI */
     while (get_bits1(&s->gb) != 0) {
         skip_bits(&s->gb, 8);
@@ -6208,6 +6292,10 @@
     if(s->avctx->debug&FF_DEBUG_PICT_INFO)
         show_pict_info(s);
 
+    if(s->pb_frame){
+        av_log(s->avctx, AV_LOG_ERROR, "PB frame mode no supported\n");
+        return -1;      /* PB frame mode */
+    }
     return 0;
 }
 
Index: libavcodec/mpegvideo.h
===================================================================
--- libavcodec/mpegvideo.h	(revision 16921)
+++ libavcodec/mpegvideo.h	(working copy)
@@ -201,6 +201,7 @@
     int bit_rate;     ///< wanted bit rate
     enum OutputFormat out_format; ///< output format
     int h263_pred;    ///< use mpeg4/h263 ac/dc predictions
+    int pb_frame;     ///< PB frame mode (0 = none, 1 = base, 2 = improved)
 
 /* the following codec id fields are deprecated in favor of codec_id */
     int h263_plus;    ///< h263 plus headers