fix and cleanup h261 mb_type selection

Originally committed as revision 3647 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h261.c

@@ -220,12 +220,11 @@ void ff_h261_encode_mb(MpegEncContext * s,
          int motion_x, int motion_y)
 {
     H261Context * h = (H261Context *)s;
-    int old_mtype, mvd, mv_diff_x, mv_diff_y, i, cbp;
+    int mvd, mv_diff_x, mv_diff_y, i, cbp;
     cbp = 63; // avoid warning
     mvd = 0;
  
     h->current_mba++;
-    old_mtype = h->mtype;
     h->mtype = 0;
  
     if (!s->mb_intra){
@@ -233,14 +232,8 @@ void ff_h261_encode_mb(MpegEncContext * s,
         cbp= get_cbp(s, block);
    
         /* mvd indicates if this block is motion compensated */
-        if(((motion_x >> 1) - h->current_mv_x != 0) || ((motion_y >> 1 ) - h->current_mv_y) != 0){
-            mvd = 1;
-        }
-        else if((motion_x >> 1 == 0) && (motion_y >> 1 == 0)){
-            mvd = 0;
-        }
-        else
-            mvd = 1;
+        mvd = motion_x | motion_y;
+
         if((cbp | mvd | s->dquant ) == 0) {
             /* skip macroblock */
             s->skip_count++;
@@ -255,14 +248,15 @@ void ff_h261_encode_mb(MpegEncContext * s,
  
     /* calculate MTYPE */
     if(!s->mb_intra){
-        h->mtype+=2;
-    if(mvd == 1){   
-        h->mtype+=2;
-        if(cbp!=0)
-            h->mtype+=1;
+        h->mtype++;
+        
+        if(mvd || s->loop_filter)
+            h->mtype+=3;
         if(s->loop_filter)
             h->mtype+=3;
-        }
+        if(cbp || s->dquant)
+            h->mtype++;
+        assert(h->mtype > 1);
     }
 
     if(s->dquant) 

tests/ffmpeg.regression.ref

@@ -35,8 +35,8 @@ a5bd577163968edab00058f2c8d5efab *./data/a-wmv2.avi
 682132 ./data/a-wmv2.avi
 09253222ab4eb95628c931a86006a2b1 *./data/out.yuv
 stddev:  8.02 PSNR:30.04 bytes:7602176
-394b91b7ef6b94e375316cc3037e68c5 *./data/a-h261.avi
-779660 ./data/a-h261.avi
+c12437d78325d6634ff77a49bf1869e8 *./data/a-h261.avi
+779222 ./data/a-h261.avi
 1dd0be7be463c1a338d1b848e926a0b8 *./data/out.yuv
 stddev:  9.17 PSNR:28.87 bytes:7602176
 fa556e599181bf9328a811a1ce9aa022 *./data/a-h263.avi

tests/rotozoom.regression.ref

@@ -35,8 +35,8 @@ stddev:  5.33 PSNR:33.58 bytes:7602176
 129214 ./data/a-wmv2.avi
 f80d2809e79af3ebcfe831deab9af03c *./data/out.yuv
 stddev:  5.33 PSNR:33.58 bytes:7602176
-39726b83734fa58d33d99098511cdb98 *./data/a-h261.avi
-194348 ./data/a-h261.avi
+41050f885f7ea9594643e5dbf8ea30da *./data/a-h261.avi
+193452 ./data/a-h261.avi
 c74fbf0b0faf1124e172413c059ab45a *./data/out.yuv
 stddev:  6.40 PSNR:31.99 bytes:7602176
 ef053b1fec77a49eb8a27510b81e4041 *./data/a-h263.avi