mpeg2 chroma422/444 support, may be slower, may be faster for other codecs

Originally committed as revision 3215 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpeg12.c

@@ -2340,7 +2340,9 @@ static int mpeg_decode_slice(Mpeg1Context *s1, int mb_y,
 #endif
 
 	s->dsp.clear_blocks(s->block[0]);
-
+        if(!s->chroma_y_shift){
+            s->dsp.clear_blocks(s->block[6]);
+        }
         ret = mpeg_decode_mb(s, s->block);
         s->chroma_qscale= s->qscale;
 
@@ -2379,8 +2381,8 @@ static int mpeg_decode_slice(Mpeg1Context *s1, int mb_y,
         }
 
         s->dest[0] += 16;
-        s->dest[1] += 8;
-        s->dest[2] += 8;
+        s->dest[1] += 16 >> s->chroma_x_shift;
+        s->dest[2] += 16 >> s->chroma_x_shift;
 
         MPV_decode_mb(s, s->block);
         

libavcodec/mpegvideo.h

@@ -670,6 +670,8 @@ typedef struct MpegEncContext {
 #define CHROMA_420 1
 #define CHROMA_422 2
 #define CHROMA_444 3
+    int chroma_x_shift;//depend on pix_format, that depend on chroma_format
+    int chroma_y_shift;
 
     int progressive_frame;
     int full_pel[2];
@@ -722,7 +724,7 @@ int DCT_common_init(MpegEncContext *s);
 void MPV_decode_defaults(MpegEncContext *s);
 int MPV_common_init(MpegEncContext *s);
 void MPV_common_end(MpegEncContext *s);
-void MPV_decode_mb(MpegEncContext *s, DCTELEM block[6][64]);
+void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64]);
 int MPV_frame_start(MpegEncContext *s, AVCodecContext *avctx);
 void MPV_frame_end(MpegEncContext *s);
 int MPV_encode_init(AVCodecContext *avctx);