mpeg1&2 aspect decoding

Originally committed as revision 1318 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpeg12.c

@@ -1431,8 +1431,9 @@ static int mpeg1_decode_picture(AVCodecContext *avctx,
 static void mpeg_decode_sequence_extension(MpegEncContext *s)
 {
     int horiz_size_ext, vert_size_ext;
-    int bit_rate_ext, vbv_buf_ext, low_delay;
+    int bit_rate_ext, vbv_buf_ext;
     int frame_rate_ext_n, frame_rate_ext_d;
+    float aspect;
 
     skip_bits(&s->gb, 8); /* profil and level */
     s->progressive_sequence = get_bits1(&s->gb); /* progressive_sequence */
@@ -1445,7 +1446,7 @@ static void mpeg_decode_sequence_extension(MpegEncContext *s)
     s->bit_rate = ((s->bit_rate / 400) | (bit_rate_ext << 12)) * 400;
     skip_bits1(&s->gb); /* marker */
     vbv_buf_ext = get_bits(&s->gb, 8);
-    low_delay = get_bits1(&s->gb);
+    s->low_delay = get_bits1(&s->gb);
     frame_rate_ext_n = get_bits(&s->gb, 2);
     frame_rate_ext_d = get_bits(&s->gb, 5);
     if (frame_rate_ext_d >= 1)
@@ -1453,6 +1454,10 @@ static void mpeg_decode_sequence_extension(MpegEncContext *s)
     dprintf("sequence extension\n");
     s->mpeg2 = 1;
     s->avctx->sub_id = 2; /* indicates mpeg2 found */
+
+    aspect= mpeg2_aspect[s->aspect_ratio_info];
+    if(aspect>0.0)      s->avctx->aspect_ratio= s->width/(aspect*s->height);
+    else if(aspect<0.0) s->avctx->aspect_ratio= -1.0/aspect;
 }
 
 static void mpeg_decode_quant_matrix_extension(MpegEncContext *s)
@@ -1706,12 +1711,18 @@ static int mpeg1_decode_sequence(AVCodecContext *avctx,
     Mpeg1Context *s1 = avctx->priv_data;
     MpegEncContext *s = &s1->mpeg_enc_ctx;
     int width, height, i, v, j;
+    float aspect;
 
     init_get_bits(&s->gb, buf, buf_size);
 
     width = get_bits(&s->gb, 12);
     height = get_bits(&s->gb, 12);
-    skip_bits(&s->gb, 4);
+    s->aspect_ratio_info= get_bits(&s->gb, 4);
+    if(!s->mpeg2){
+        aspect= mpeg1_aspect[s->aspect_ratio_info];
+        if(aspect!=0.0) avctx->aspect_ratio= width/(aspect*height);
+    }
+
     s->frame_rate_index = get_bits(&s->gb, 4);
     if (s->frame_rate_index == 0)
         return -1;
@@ -1896,6 +1907,9 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
                                           s->buffer, input_size);
                     break;
                 default:
+                    if (start_code >= SLICE_MIN_START_CODE &&
+                        start_code <= SLICE_MAX_START_CODE) {
+                        
                         /* skip b frames if we dont have reference frames */
                         if(s2->last_picture.data[0]==NULL && s2->pict_type==B_TYPE) break;
                         /* skip b frames if we are in a hurry */
@@ -1903,8 +1917,6 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
                         /* skip everything if we are in a hurry>=5 */
                         if(avctx->hurry_up>=5) break;
 
-                    if (start_code >= SLICE_MIN_START_CODE &&
-                        start_code <= SLICE_MAX_START_CODE) {
                         ret = mpeg_decode_slice(avctx, picture,
                                                 start_code, s->buffer, input_size);
                         if (ret == DECODE_SLICE_EOP) {

libavcodec/mpeg12data.h

@@ -411,4 +411,32 @@ UINT8 ff_mpeg1_dc_scale_table[128]={ // MN: mpeg2 really can have such large qsc
     8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
 };
 
+static const float mpeg1_aspect[16]={
+    0.0000,
+    1.0000,
+    0.6735,
+    0.7031,
+    
+    0.7615,
+    0.8055,
+    0.8437,
+    0.8935,
+
+    0.9157,
+    0.9815,
+    1.0255,
+    1.0695,
+
+    1.0950,
+    1.1575,
+    1.2015,
+};
+
+static const float mpeg2_aspect[16]={
+    0,
+    1.0,
+    -3.0/4.0,
+    -9.0/16.0,
+    -1.0/2.21,
+};