mpeg4 b-frames :)

create slightly more correct headers & add "ffmpeg" user-data section

Originally committed as revision 328 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h263dec.c

@@ -45,6 +45,7 @@ static int h263_decode_init(AVCodecContext *avctx)
     case CODEC_ID_MPEG4:
         s->time_increment_bits = 4; /* default value for broken headers */
         s->h263_pred = 1;
+        s->has_b_frames = 1;
         break;
     case CODEC_ID_MSMPEG4:
         s->h263_msmpeg4 = 1;
@@ -219,9 +220,15 @@ static int h263_decode_frame(AVCodecContext *avctx,
 
     MPV_frame_end(s);
     
-    pict->data[0] = s->current_picture[0];
-    pict->data[1] = s->current_picture[1];
-    pict->data[2] = s->current_picture[2];
+    if(s->pict_type==B_TYPE){
+        pict->data[0] = s->current_picture[0];
+        pict->data[1] = s->current_picture[1];
+        pict->data[2] = s->current_picture[2];
+    } else {
+        pict->data[0] = s->last_picture[0];
+        pict->data[1] = s->last_picture[1];
+        pict->data[2] = s->last_picture[2];
+    }
     pict->linesize[0] = s->linesize;
     pict->linesize[1] = s->linesize / 2;
     pict->linesize[2] = s->linesize / 2;

libavcodec/mpeg4data.h

@@ -99,3 +99,7 @@ static const UINT16 sprite_trajectory_tab[15][2] = {
  {0x0E, 4}, {0x1E, 5},  {0x3E, 6},  {0x7E, 7}, {0xFE, 8}, 
  {0x1FE, 9},{0x3FE, 10},{0x7FE, 11},{0xFFE, 12},
 };
+
+static const UINT8 mb_type_b_tab[4][2] = {
+ {1, 1}, {1, 2}, {1, 3}, {1, 4},
+};

libavcodec/mpegvideo.c

@@ -430,6 +430,7 @@ void MPV_frame_start(MpegEncContext *s)
             s->current_picture[i] = s->aux_picture[i];
         }
     } else {
+        s->last_non_b_pict_type= s->pict_type;
         for(i=0;i<3;i++) {
             /* swap next and last */
             tmp = s->last_picture[i];
@@ -745,7 +746,7 @@ static inline void MPV_motion(MpegEncContext *s,
                         ref_picture, 0,
                         16);
 #endif
-        }else if(s->quarter_sample){
+        }else if(s->quarter_sample && dir==0){ //FIXME
             qpel_motion(s, dest_y, dest_cb, dest_cr, 0,
                         ref_picture, 0,
                         0, pix_op, qpix_op,
@@ -930,8 +931,9 @@ void MPV_decode_mb(MpegEncContext *s, DCTELEM block[6][64])
     else if (s->h263_pred || s->h263_aic)
         s->mbintra_table[mb_x + mb_y*s->mb_width]=1;
 
-    /* update motion predictor */
+    /* update motion predictor, not for B-frames as they need the motion_val from the last P/S-Frame */
     if (s->out_format == FMT_H263) {
+      if(s->pict_type!=B_TYPE){
         int xy, wrap, motion_x, motion_y;
         
         wrap = 2 * s->mb_width + 2;
@@ -954,6 +956,7 @@ void MPV_decode_mb(MpegEncContext *s, DCTELEM block[6][64])
             s->motion_val[xy + 1 + wrap][0] = motion_x;
             s->motion_val[xy + 1 + wrap][1] = motion_y;
         }
+      }
     }
     
     if (!s->intra_only) {

libavcodec/mpegvideo.h

@@ -84,19 +84,21 @@ typedef struct MpegEncContext {
 
     int qscale;
     int pict_type;
+    int last_non_b_pict_type; /* used for mpeg4 gmc b-frames */
     int frame_rate_index;
     /* motion compensation */
     int unrestricted_mv;
     int h263_long_vectors; /* use horrible h263v1 long vector mode */
 
     int f_code; /* resolution */
-    int b_code; /* resolution for B Frames*/
-    INT16 *mv_table[2];    /* MV table */
-    INT16 (*motion_val)[2]; /* used for MV prediction */
+    int b_code; /* backward resolution for B Frames (mpeg4) */
+    INT16 *mv_table[2];    /* MV table (1MV per MB)*/
+    INT16 (*motion_val)[2]; /* used for MV prediction (4MV per MB)*/
     int full_search;
     int mv_dir;
 #define MV_DIR_BACKWARD  1
 #define MV_DIR_FORWARD   2
+#define MV_DIRECT        4 // bidirectional mode where the difference equals the MV of the last P/S/I-Frame (mpeg4)
     int mv_type;
 #define MV_TYPE_16X16       0   /* 1 vector for the whole mb */
 #define MV_TYPE_8X8         1   /* 4 vectors (h263) */
@@ -156,7 +158,12 @@ typedef struct MpegEncContext {
     int h263_aic_dir; /* AIC direction: 0 = left, 1 = top */
     
     /* mpeg4 specific */
+    int time_increment_resolution;
     int time_increment_bits;
+    int time_increment;
+    int time_base;
+    int time;
+    int last_non_b_time[2];
     int shape;
     int vol_sprite_usage;
     int sprite_width;