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

[Kostya]

On Fri, Feb 20, 2009 at 01:09:08PM +0100, Michael Niedermayer wrote:
> On Fri, Feb 20, 2009 at 11:37:40AM +0200, Kostya wrote:
[...]
> > 
> > This one should be right.
> 
> ok

I'll apply it after code thaw then (i.e. next week).
For now here are the patches for H.263 picture header parsing and actual
PB-frame decoding for all of them.
 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
-------------- next part --------------
Index: libavcodec/h263.c
===================================================================
--- libavcodec/h263.c	(revision 16921)
+++ libavcodec/h263.c	(working copy)
@@ -5047,10 +5111,7 @@
         s->obmc= get_bits1(&s->gb); /* Advanced prediction mode */
         s->unrestricted_mv = s->h263_long_vectors || s->obmc;
 
-        if (get_bits1(&s->gb) != 0) {
-            av_log(s->avctx, AV_LOG_ERROR, "H263 PB frame not supported\n");
-            return -1; /* not PB frame */
-        }
+        s->pb_frame = get_bits1(&s->gb);
         s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
         skip_bits1(&s->gb); /* Continuous Presence Multipoint mode: off */
 
@@ -5105,6 +5166,7 @@
         switch(s->pict_type){
         case 0: s->pict_type= FF_I_TYPE;break;
         case 1: s->pict_type= FF_P_TYPE;break;
+        case 2: s->pict_type= FF_P_TYPE;s->pb_frame = 3;break;
         case 3: s->pict_type= FF_B_TYPE;break;
         case 7: s->pict_type= FF_I_TYPE;break; //ZYGO
         default:
@@ -5194,6 +5256,16 @@
     s->mb_height = (s->height  + 15) / 16;
     s->mb_num = s->mb_width * s->mb_height;
 
+    if (s->pb_frame) {
+        skip_bits(&s->gb, 3); /* Temporal reference for B-pictures */
+        if (s->custom_pcf)
+            skip_bits(&s->gb, 2); //extended Temporal reference
+        skip_bits(&s->gb, 2); /* Quantization information for B-pictures */
+
+        av_log(s->avctx, AV_LOG_ERROR, "PB frame mode no supported\n");
+        return -1;      /* PB frame mode */
+    }
+
     /* PEI */
     while (get_bits1(&s->gb) != 0) {
         skip_bits(&s->gb, 8);
-------------- next part --------------
Index: libavcodec/h263.c
===================================================================
--- libavcodec/h263.c	(revision 16921)
+++ libavcodec/h263.c	(working copy)
@@ -40,6 +40,7 @@
 #include "h263data.h"
 #include "mpeg4data.h"
 #include "mathops.h"
+#include "unary.h"
 
 //#undef NDEBUG
 //#include <assert.h>
@@ -3886,12 +3887,52 @@
     ff_set_qscale(s, s->qscale);
 }
 
+static int h263_skip_b_part(MpegEncContext *s, int cbp)
+{
+    DECLARE_ALIGNED(16, DCTELEM, dblock[64]);
+    int i;
+
+    for (i = 0; i < 6; i++) {
+        if (h263_decode_block(s, dblock, i, cbp&32) < 0)
+            return -1;
+        cbp+=cbp;
+    }
+    return 0;
+}
+
+static int h263_get_modb(GetBitContext *gb, int pb_frame, int *cbpb)
+{
+    int c, mv = 1;
+
+    switch(pb_frame){
+    case 1: // h.263 and i263 PB-frame
+        c = get_bits1(gb);
+        break;
+    case 2: // i263 improved PB-frame
+        c = get_bits1(gb);
+        if(c)
+            mv = !get_bits1(gb);        
+        break;
+    case 3: // h.263 improved PB-frame
+        mv = get_unary(gb, 0, 4) + 1;
+        c = mv & 1;
+        mv = !!(mv & 2);
+        break;
+    default:
+        return -1;
+    }
+    if(c)
+        *cbpb = get_bits(gb, 6);
+    return mv;
+}
+
 int ff_h263_decode_mb(MpegEncContext *s,
                       DCTELEM block[6][64])
 {
     int cbpc, cbpy, i, cbp, pred_x, pred_y, mx, my, dquant;
     int16_t *mot_val;
     const int xy= s->mb_x + s->mb_y * s->mb_stride;
+    int cbpb = 0, pb_mv_count = 0;
 
     assert(!s->h263_pred);
 
@@ -3924,6 +3965,8 @@
         s->mb_intra = ((cbpc & 4) != 0);
         if (s->mb_intra) goto intra;
 
+        if(s->pb_frame && get_bits1(&s->gb))
+            pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
         cbpy = get_vlc2(&s->gb, cbpy_vlc.table, CBPY_VLC_BITS, 1);
 
         if(s->alt_inter_vlc==0 || (cbpc & 3)!=3)
@@ -3987,12 +4030,19 @@
             }
         }
 
+        if(pb_mv_count){
+            h263_decode_motion(s, 0, 1);
+            h263_decode_motion(s, 0, 1);
+        }
+
         /* decode each block */
         for (i = 0; i < 6; i++) {
             if (h263_decode_block(s, block[i], i, cbp&32) < 0)
                 return -1;
             cbp+=cbp;
         }
+        if(s->pb_frame && h263_skip_b_part(s, cbpb))
+            return -1;
 
         if(s->obmc){
             if(s->pict_type == FF_P_TYPE && s->mb_x+1<s->mb_width && s->mb_num_left != 1)
@@ -4118,6 +4168,8 @@
         }else
             s->ac_pred = 0;
 
+        if(s->pb_frame && get_bits1(&s->gb))
+            pb_mv_count = h263_get_modb(&s->gb, s->pb_frame, &cbpb);
         cbpy = get_vlc2(&s->gb, cbpy_vlc.table, CBPY_VLC_BITS, 1);
         if(cbpy<0){
             av_log(s->avctx, AV_LOG_ERROR, "I cbpy damaged at %d %d\n", s->mb_x, s->mb_y);
@@ -4128,12 +4180,24 @@
             h263_decode_dquant(s);
         }
 
+        pb_mv_count += !!s->pb_frame;
+        while(pb_mv_count--){
+            h263_decode_motion(s, 0, 1);
+            h263_decode_motion(s, 0, 1);
+        }
+
         /* decode each block */
         for (i = 0; i < 6; i++) {
             if (h263_decode_block(s, block[i], i, cbp&32) < 0)
                 return -1;
             cbp+=cbp;
         }
+        if(s->pb_frame){
+            s->mb_intra = 0;
+            if(h263_skip_b_part(s, cbpb))
+                return -1;
+            s->mb_intra = 1;
+        }
     }
 end: