fix IPCM_decode_error.h264

Originally committed as revision 14135 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h264.c

@@ -4352,12 +4352,11 @@ static int decode_residual(H264Context *h, GetBitContext *gb, DCTELEM *block, in
                 level_code= (prefix<<suffix_length) + get_bits(gb, suffix_length); //part
             else
                 level_code= prefix + get_bits(gb, 4); //part
-        }else if(prefix==15){
-            level_code= (prefix<<suffix_length) + get_bits(gb, 12); //part
-            if(suffix_length==0) level_code+=15; //FIXME doesn't make (much)sense
         }else{
-            av_log(h->s.avctx, AV_LOG_ERROR, "prefix too large at %d %d\n", s->mb_x, s->mb_y);
-            return -1;
+            level_code= (15<<suffix_length) + get_bits(gb, prefix-3); //part
+            if(suffix_length==0) level_code+=15; //FIXME doesn't make (much)sense
+            if(prefix>=16)
+                level_code += (1<<(prefix-3))-4096;
         }
 
         if(trailing_ones < 3) level_code += 2;
@@ -4375,11 +4374,10 @@ static int decode_residual(H264Context *h, GetBitContext *gb, DCTELEM *block, in
             prefix = get_level_prefix(gb);
             if(prefix<15){
                 level_code = (prefix<<suffix_length) + get_bits(gb, suffix_length);
-            }else if(prefix==15){
-                level_code =  (prefix<<suffix_length) + get_bits(gb, 12);
             }else{
-                av_log(h->s.avctx, AV_LOG_ERROR, "prefix too large at %d %d\n", s->mb_x, s->mb_y);
-                return -1;
+                level_code = (15<<suffix_length) + get_bits(gb, prefix-3);
+                if(prefix>=16)
+                    level_code += (1<<(prefix-3))-4096;
             }
             mask= -(level_code&1);
             level[i]= (((2+level_code)>>1) ^ mask) - mask;