fixing illegal 3. esc bug (the mpeg4 std only requires encoders to use...

fixing illegal 3. esc bug (the mpeg4 std only requires encoders to use unescaped symbols but not esc1 or esc2 if they are shorter than esc3, andjust beause its logical to use the shortest possible vlc doesnt mean encoders do that)

Originally committed as revision 1304 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -548,12 +548,16 @@ typedef struct AVCodecContext {
     float b_quant_offset;
     
     /**
-     * error resilience {-1,0,1} higher values will detect more errors but may missdetect
+     * error resilience higher values will detect more errors but may missdetect
      * some more or less valid parts as errors
      * encoding: unused
      * decoding: set by user
      */
     int error_resilience;
+#define FF_ER_CAREFULL        1
+#define FF_ER_COMPLIANT       2
+#define FF_ER_AGGRESSIVE      3
+#define FF_ER_VERY_AGGRESSIVE 4
     
     /**
      * called at the beginning of each frame to get a buffer for it.

libavcodec/h263.c

@@ -3624,19 +3624,21 @@ static inline int mpeg4_decode_block(MpegEncContext * s, DCTELEM * block,
 #if 1 
                     {
                         const int abs_level= ABS(level);
-                        if(abs_level<=MAX_LEVEL && run<=MAX_RUN && ((s->workaround_bugs&FF_BUG_AC_VLC)==0)){
+                        if(abs_level<=MAX_LEVEL && run<=MAX_RUN){
                             const int run1= run - rl->max_run[last][abs_level] - 1;
                             if(abs_level <= rl->max_level[last][run]){
                                 fprintf(stderr, "illegal 3. esc, vlc encoding possible\n");
                                 return -1;
                             }
-                            if(abs_level <= rl->max_level[last][run]*2){
-                                fprintf(stderr, "illegal 3. esc, esc 1 encoding possible\n");
-                                return -1;
-                            }
-                            if(run1 >= 0 && abs_level <= rl->max_level[last][run1]){
-                                fprintf(stderr, "illegal 3. esc, esc 2 encoding possible\n");
-                                return -1;
+                            if(s->error_resilience > FF_ER_COMPLIANT){
+                                if(abs_level <= rl->max_level[last][run]*2){
+                                    fprintf(stderr, "illegal 3. esc, esc 1 encoding possible\n");
+                                    return -1;
+                                }
+                                if(run1 >= 0 && abs_level <= rl->max_level[last][run1]){
+                                    fprintf(stderr, "illegal 3. esc, esc 2 encoding possible\n");
+                                    return -1;
+                                }
                             }
                         }
                     }