make mpeg decoder handle mid-stream changes in resolution

patch by Heikki Lindholm holindho at cs helsinki fi
original thread: [Ffmpeg-devel] [PATCH] fix mid-stream resolution changes
date: Sat Mar 31 13:52:50 CEST 2007

Originally committed as revision 8865 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpeg12.c

@@ -2084,6 +2084,7 @@ typedef struct Mpeg1Context {
     int slice_count;
     int swap_uv;//indicate VCR2
     int save_aspect_info;
+    int save_width, save_height;
     AVRational frame_rate_ext;       ///< MPEG-2 specific framerate modificator
 
 } Mpeg1Context;
@@ -2138,6 +2139,8 @@ static int mpeg_decode_postinit(AVCodecContext *avctx){
         (s1->mpeg_enc_ctx_allocated == 0)||
         avctx->coded_width  != s->width ||
         avctx->coded_height != s->height||
+        s1->save_width != s->width ||
+        s1->save_height != s->height ||
         s1->save_aspect_info != s->aspect_ratio_info||
         0)
     {
@@ -2155,6 +2158,8 @@ static int mpeg_decode_postinit(AVCodecContext *avctx){
         avcodec_set_dimensions(avctx, s->width, s->height);
         avctx->bit_rate = s->bit_rate;
         s1->save_aspect_info = s->aspect_ratio_info;
+        s1->save_width = s->width;
+        s1->save_height = s->height;
 
      //low_delay may be forced, in this case we will have B frames
      //that behave like P frames