improving 3IV1 support (still far from perfect) note, disabled as it requires...

improving 3IV1 support (still far from perfect) note, disabled as it requires some checks in the inner loops which would slow things down a tiny bit

Originally committed as revision 1889 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h263.c

@@ -102,6 +102,11 @@ max run: 29/41
 */
 #endif
 
+#if 0 //3IV1 is quite rare and tis slows things down a tiny bit
+#define IS_3IV1 s->avctx->codec_tag == ff_get_fourcc("3IV1")
+#else 
+#define IS_3IV1 0
+#endif
 
 int h263_get_picture_format(int width, int height)
 {
@@ -643,6 +648,7 @@ void mpeg4_encode_mb(MpegEncContext * s,
                         s->last_bits++;
                     }
                     s->skip_count++;
+                    
                     return;
                 }
             }
@@ -1828,6 +1834,9 @@ static inline int ff_mpeg4_pred_dc(MpegEncContext * s, int n, uint16_t **dc_val_
     } else {
 	scale = s->c_dc_scale;
     }
+    if(IS_3IV1)
+        scale= 8;
+
     wrap= s->block_wrap[n];
     dc_val = s->dc_val[0] + s->block_index[n];
 
@@ -3603,7 +3612,19 @@ static inline int mpeg4_decode_dc(MpegEncContext * s, int n, int *dir_ptr)
     if (code == 0) {
         level = 0;
     } else {
-        level = get_xbits(&s->gb, code);
+        if(IS_3IV1){
+            if(code==1)
+                level= 2*get_bits1(&s->gb)-1;
+            else{
+                if(get_bits1(&s->gb))
+                    level = get_bits(&s->gb, code-1) + (1<<(code-1));
+                else
+                    level = -get_bits(&s->gb, code-1) - (1<<(code-1));
+            }
+        }else{
+            level = get_xbits(&s->gb, code);
+        }
+
         if (code > 8){
             if(get_bits1(&s->gb)==0){ /* marker */
                 if(s->error_resilience>=2){
@@ -3627,6 +3648,9 @@ static inline int mpeg4_decode_dc(MpegEncContext * s, int n, int *dir_ptr)
     } else {
         *dc_val = level * s->c_dc_scale;
     }
+    if(IS_3IV1)
+        *dc_val = level * 8;
+    
     if(s->error_resilience>=3){
         if(*dc_val > 2048 + s->y_dc_scale + s->c_dc_scale){
             fprintf(stderr, "dc overflow at %dx%d\n", s->mb_x, s->mb_y);
@@ -3750,10 +3774,14 @@ static inline int mpeg4_decode_block(MpegEncContext * s, DCTELEM * block,
                 SKIP_COUNTER(re, &s->gb, 1+11+5+1);
 
                 i+= run + 1;
-                if(last) i+=192;    
+                if(last) i+=192;
           }else{
             int cache;
             cache= GET_CACHE(re, &s->gb);
+
+            if(IS_3IV1) 
+                cache ^= 0xC0000000;
+
             if (cache&0x80000000) {
                 if (cache&0x40000000) {
                     /* third escape */
@@ -3763,20 +3791,24 @@ static inline int mpeg4_decode_block(MpegEncContext * s, DCTELEM * block,
                     SKIP_COUNTER(re, &s->gb, 2+1+6);
                     UPDATE_CACHE(re, &s->gb);
 
-                    if(SHOW_UBITS(re, &s->gb, 1)==0){
-                        fprintf(stderr, "1. marker bit missing in 3. esc\n");
-                        return -1;
-                    }; SKIP_CACHE(re, &s->gb, 1);
-                    
-                    level= SHOW_SBITS(re, &s->gb, 12); SKIP_CACHE(re, &s->gb, 12);
+                    if(IS_3IV1){
+                        level= SHOW_SBITS(re, &s->gb, 12); LAST_SKIP_BITS(re, &s->gb, 12);
+                    }else{
+                        if(SHOW_UBITS(re, &s->gb, 1)==0){
+                            fprintf(stderr, "1. marker bit missing in 3. esc\n");
+                            return -1;
+                        }; SKIP_CACHE(re, &s->gb, 1);
+
+                        level= SHOW_SBITS(re, &s->gb, 12); SKIP_CACHE(re, &s->gb, 12);
+
+                        if(SHOW_UBITS(re, &s->gb, 1)==0){
+                            fprintf(stderr, "2. marker bit missing in 3. esc\n");
+                            return -1;
+                        }; LAST_SKIP_CACHE(re, &s->gb, 1);
+
+                        SKIP_COUNTER(re, &s->gb, 1+12+1);
+                    }
  
-                    if(SHOW_UBITS(re, &s->gb, 1)==0){
-                        fprintf(stderr, "2. marker bit missing in 3. esc\n");
-                        return -1;
-                    }; LAST_SKIP_CACHE(re, &s->gb, 1);
-                    
-                    SKIP_COUNTER(re, &s->gb, 1+12+1);
-                    
                     if(level*s->qscale>1024 || level*s->qscale<-1024){
                         fprintf(stderr, "|level| overflow in 3. esc, qp=%d\n", s->qscale);
                         return -1;
@@ -4738,12 +4770,12 @@ static int decode_vop_header(MpegEncContext *s, GetBitContext *gb){
              s->b_code=1;
 
          if(s->avctx->debug&FF_DEBUG_PICT_INFO){
-             printf("qp:%d fc:%d,%d %s size:%d pro:%d alt:%d top:%d %spel part:%d resync:%d w:%d a:%d\n", 
+             printf("qp:%d fc:%d,%d %s size:%d pro:%d alt:%d top:%d %spel part:%d resync:%d w:%d a:%d rnd:%d\n", 
                  s->qscale, s->f_code, s->b_code, 
                  s->pict_type == I_TYPE ? "I" : (s->pict_type == P_TYPE ? "P" : (s->pict_type == B_TYPE ? "B" : "S")), 
                  gb->size_in_bits,s->progressive_sequence, s->alternate_scan, s->top_field_first, 
                  s->quarter_sample ? "q" : "h", s->data_partitioning, s->resync_marker, s->num_sprite_warping_points,
-                 s->sprite_warping_accuracy); 
+                 s->sprite_warping_accuracy, 1-s->no_rounding); 
          }
 
          if(!s->scalability){