Change 4xm demuxer and video decoder to pass the video format version in

extradata instead of codec_tag.

Originally committed as revision 10253 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/4xm.c

@@ -789,7 +789,12 @@ static void common_init(AVCodecContext *avctx){
 static int decode_init(AVCodecContext *avctx){
     FourXContext * const f = avctx->priv_data;
 
-    f->version= avctx->codec_tag == 0x40000;
+    if(avctx->extradata_size != 4 || !avctx->extradata) {
+        av_log(avctx, AV_LOG_ERROR, "extradata wrong or missing\n");
+        return 1;
+    }
+
+    f->version= AV_RL32(avctx->extradata) == 0x40000;
     common_init(avctx);
     init_vlcs(f);
 

libavformat/4xm.c

@@ -149,7 +149,9 @@ static int fourxm_read_header(AVFormatContext *s,
 
             st->codec->codec_type = CODEC_TYPE_VIDEO;
             st->codec->codec_id = CODEC_ID_4XM;
-            st->codec->codec_tag = AV_RL32(&header[i + 16]);
+            st->codec->extradata_size = 4;
+            st->codec->extradata = av_malloc(4);
+            AV_WL32(st->codec->extradata, AV_RL32(&header[i + 16]));
             st->codec->width = fourxm->width;
             st->codec->height = fourxm->height;