matroskadec: use a temporary fourcc variable

libavformat/matroskadec.c

@@ -1281,6 +1281,7 @@ static int matroska_read_header(AVFormatContext *s, AVFormatParameters *ap)
         uint8_t *extradata = NULL;
         int extradata_size = 0;
         int extradata_offset = 0;
+        uint32_t fourcc = 0;
         AVIOContext b;
 
         /* Apply some sanity checks. */
@@ -1302,6 +1303,7 @@ static int matroska_read_header(AVFormatContext *s, AVFormatParameters *ap)
                 track->video.display_width = track->video.pixel_width;
             if (!track->video.display_height)
                 track->video.display_height = track->video.pixel_height;
+            fourcc = track->video.fourcc;
         } else if (track->type == MATROSKA_TRACK_TYPE_AUDIO) {
             if (!track->audio.out_samplerate)
                 track->audio.out_samplerate = track->audio.samplerate;
@@ -1361,8 +1363,8 @@ static int matroska_read_header(AVFormatContext *s, AVFormatParameters *ap)
             && track->codec_priv.size >= 40
             && track->codec_priv.data != NULL) {
             track->ms_compat = 1;
-            track->video.fourcc = AV_RL32(track->codec_priv.data + 16);
-            codec_id = ff_codec_get_id(ff_codec_bmp_tags, track->video.fourcc);
+            fourcc = AV_RL32(track->codec_priv.data + 16);
+            codec_id = ff_codec_get_id(ff_codec_bmp_tags, fourcc);
             extradata_offset = 40;
         } else if (!strcmp(track->codec_id, "A_MS/ACM")
                    && track->codec_priv.size >= 14
@@ -1378,8 +1380,8 @@ static int matroska_read_header(AVFormatContext *s, AVFormatParameters *ap)
         } else if (!strcmp(track->codec_id, "V_QUICKTIME")
                    && (track->codec_priv.size >= 86)
                    && (track->codec_priv.data != NULL)) {
-            track->video.fourcc = AV_RL32(track->codec_priv.data);
-            codec_id=ff_codec_get_id(codec_movvideo_tags, track->video.fourcc);
+            fourcc = AV_RL32(track->codec_priv.data);
+            codec_id = ff_codec_get_id(codec_movvideo_tags, fourcc);
         } else if (codec_id == CODEC_ID_PCM_S16BE) {
             switch (track->audio.bitdepth) {
             case  8:  codec_id = CODEC_ID_PCM_U8;     break;
@@ -1500,7 +1502,7 @@ static int matroska_read_header(AVFormatContext *s, AVFormatParameters *ap)
             MatroskaTrackPlane *planes = track->operation.combine_planes.elem;
 
             st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
-            st->codec->codec_tag  = track->video.fourcc;
+            st->codec->codec_tag  = fourcc;
             st->codec->width  = track->video.pixel_width;
             st->codec->height = track->video.pixel_height;
             av_reduce(&st->sample_aspect_ratio.num,