mpeg1 bframe encoding patch by (Raphaël LEGRAND) with some modifications by me

Originally committed as revision 1551 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffmpeg.c

@@ -2234,10 +2234,6 @@ void opt_output_file(const char *filename)
                
             
                 if (b_frames) {
-                    if (codec_id != CODEC_ID_MPEG4) {
-                        fprintf(stderr, "\nB frames encoding only supported by MPEG-4.\n");
-                        exit(1);
-                    }
                     video_enc->max_b_frames = b_frames;
                     video_enc->b_frame_strategy = 0;
                     video_enc->b_quant_factor = 2.0;

libavcodec/motion_est.c

@@ -1493,12 +1493,13 @@ void ff_estimate_b_frame_motion(MpegEncContext * s,
     fbmin= bidir_refine(s, mb_x, mb_y) + penalty_factor;
 //printf("%d %d %d %d\n", dmin, fmin, bmin, fbmin);
     {
-        int score= dmin;
-        type=MB_TYPE_DIRECT;
+        int score= fmin;
+        type = MB_TYPE_FORWARD;
         
-        if(fmin<score){
-            score=fmin;
-            type= MB_TYPE_FORWARD; 
+        // RAL: No MB_TYPE_DIRECT in MPEG-1 video (only MPEG-4)
+        if (s->codec_id != CODEC_ID_MPEG1VIDEO && dmin <= score){
+            score = dmin;
+            type = MB_TYPE_DIRECT;
         }
         if(bmin<score){
             score=bmin;
@@ -1643,21 +1644,32 @@ void ff_fix_long_b_mvs(MpegEncContext * s, int16_t (*mv_table)[2], int f_code, i
     int y;
     UINT8 * fcode_tab= s->fcode_tab;
 
+    // RAL: 8 in MPEG-1, 16 in MPEG-4
+    int range = (((s->codec_id == CODEC_ID_MPEG1VIDEO) ? 8 : 16) << f_code);
+
     /* clip / convert to intra 16x16 type MVs */
     for(y=0; y<s->mb_height; y++){
         int x;
         int xy= (y+1)* (s->mb_width+2)+1;
         int i= y*s->mb_width;
-        for(x=0; x<s->mb_width; x++){
-            if(   fcode_tab[mv_table[xy][0] + MAX_MV] > f_code
-               || fcode_tab[mv_table[xy][0] + MAX_MV] == 0){
-                if(mv_table[xy][0]>0) mv_table[xy][0]=  (16<<f_code)-1;
-                else                  mv_table[xy][0]= -(16<<f_code);
-            }
-            if(   fcode_tab[mv_table[xy][1] + MAX_MV] > f_code
-               || fcode_tab[mv_table[xy][1] + MAX_MV] == 0){
-                if(mv_table[xy][1]>0) mv_table[xy][1]=  (16<<f_code)-1;
-                else                  mv_table[xy][1]= -(16<<f_code);
+        for(x=0; x<s->mb_width; x++)
+            {
+            if (s->mb_type[i] & type)    // RAL: "type" test added...
+                {
+                if (fcode_tab[mv_table[xy][0] + MAX_MV] > f_code || fcode_tab[mv_table[xy][0] + MAX_MV] == 0)
+                    {
+                    if(mv_table[xy][0]>0) 
+                        mv_table[xy][0]=  range-1;
+                    else
+                        mv_table[xy][0]= -range;
+                    }
+                if (fcode_tab[mv_table[xy][1] + MAX_MV] > f_code || fcode_tab[mv_table[xy][1] + MAX_MV] == 0)
+                    {
+                    if(mv_table[xy][1]>0) 
+                        mv_table[xy][1]=  range-1;
+                    else                  
+                        mv_table[xy][1]= -range;
+            }
             }
             xy++;
             i++;

libavcodec/mpegvideo.c

@@ -2872,7 +2872,8 @@ static void encode_picture(MpegEncContext *s, int picture_number)
 
 #ifdef CONFIG_RISKY
     /* we need to initialize some time vars before we can encode b-frames */
-    if (s->h263_pred && !s->h263_msmpeg4)
+    // RAL: Condition added for MPEG1VIDEO
+    if (s->codec_id == CODEC_ID_MPEG1VIDEO || (s->h263_pred && !s->h263_msmpeg4))
         ff_set_mpeg4_time(s, s->picture_number); 
 #endif
         
@@ -2965,12 +2966,24 @@ static void encode_picture(MpegEncContext *s, int picture_number)
 //printf("Scene change detected, encoding as I Frame %d %d\n", s->current_picture.mb_var_sum, s->current_picture.mc_mb_var_sum);
     }
 
-    if(s->pict_type==P_TYPE || s->pict_type==S_TYPE) 
+    if(s->pict_type==P_TYPE || s->pict_type==S_TYPE) {
         s->f_code= ff_get_best_fcode(s, s->p_mv_table, MB_TYPE_INTER);
+        
+        // RAL: Next call moved into that bloc
         ff_fix_long_p_mvs(s);
+    }
+
+    // RAL: All this bloc changed
     if(s->pict_type==B_TYPE){
-        s->f_code= ff_get_best_fcode(s, s->b_forw_mv_table, MB_TYPE_FORWARD);
-        s->b_code= ff_get_best_fcode(s, s->b_back_mv_table, MB_TYPE_BACKWARD);
+        int a, b;
+
+        a = ff_get_best_fcode(s, s->b_forw_mv_table, MB_TYPE_FORWARD);
+        b = ff_get_best_fcode(s, s->b_bidir_forw_mv_table, MB_TYPE_BIDIR);
+        s->f_code = FFMAX(a, b);
+
+        a = ff_get_best_fcode(s, s->b_back_mv_table, MB_TYPE_BACKWARD);
+        b = ff_get_best_fcode(s, s->b_bidir_back_mv_table, MB_TYPE_BIDIR);
+        s->b_code = FFMAX(a, b);
 
         ff_fix_long_b_mvs(s, s->b_forw_mv_table, s->f_code, MB_TYPE_FORWARD);
         ff_fix_long_b_mvs(s, s->b_back_mv_table, s->b_code, MB_TYPE_BACKWARD);
@@ -3064,6 +3077,10 @@ static void encode_picture(MpegEncContext *s, int picture_number)
     s->mb_incr = 1;
     s->last_mv[0][0][0] = 0;
     s->last_mv[0][0][1] = 0;
+    s->last_mv[1][0][0] = 0;
+    s->last_mv[1][0][1] = 0;
+     
+    s->last_mv_dir = 0;
 
 #ifdef CONFIG_RISKY
     if (s->codec_id==CODEC_ID_H263 || s->codec_id==CODEC_ID_H263P)
@@ -3227,7 +3244,7 @@ static void encode_picture(MpegEncContext *s, int picture_number)
                                  &dmin, &next_block, mx, my);
                 }
                 if(mb_type&MB_TYPE_INTRA){
-                    s->mv_dir = MV_DIR_FORWARD;
+                    s->mv_dir = 0;
                     s->mv_type = MV_TYPE_16X16;
                     s->mb_intra= 1;
                     s->mv[0][0][0] = 0;
@@ -3348,7 +3365,7 @@ static void encode_picture(MpegEncContext *s, int picture_number)
                 
                 switch(mb_type){
                 case MB_TYPE_INTRA:
-                    s->mv_dir = MV_DIR_FORWARD;
+                    s->mv_dir = 0;
                     s->mb_intra= 1;
                     motion_x= s->mv[0][0][0] = 0;
                     motion_y= s->mv[0][0][1] = 0;
@@ -3405,8 +3422,13 @@ static void encode_picture(MpegEncContext *s, int picture_number)
                     motion_x=motion_y=0; //gcc warning fix
                     printf("illegal MB type\n");
                 }
+
                 encode_mb(s, motion_x, motion_y);
+
+                // RAL: Update last macrobloc type
+                s->last_mv_dir = s->mv_dir;
             }
+
             /* clean the MV table in IPS frames for direct mode in B frames */
             if(s->mb_intra /* && I,P,S_TYPE */){
                 s->p_mv_table[xy][0]=0;

libavcodec/mpegvideo.h

@@ -508,6 +508,7 @@ typedef struct MpegEncContext {
     /* Mpeg1 specific */
     int fake_picture_number; /* picture number at the bitstream frame rate */
     int gop_picture_number;  /* index of the first picture of a GOP based on fake_pic_num & mpeg1 specific */
+    int last_mv_dir;         /* last mv_dir, used for b frame encoding */
     
     /* MPEG2 specific - I wish I had not to support this mess. */
     int progressive_sequence;