matroskadec: properly decode color space in an endian neutral way

libavformat/matroskadec.c

@@ -112,7 +112,7 @@ typedef struct {
     uint64_t display_height;
     uint64_t pixel_width;
     uint64_t pixel_height;
-    uint64_t fourcc;
+    EbmlBin color_space;
     uint64_t stereo_mode;
 } MatroskaTrackVideo;
 
@@ -302,7 +302,7 @@ static EbmlSyntax matroska_track_video[] = {
     { MATROSKA_ID_VIDEODISPLAYHEIGHT, EBML_UINT, 0, offsetof(MatroskaTrackVideo,display_height) },
     { MATROSKA_ID_VIDEOPIXELWIDTH,    EBML_UINT, 0, offsetof(MatroskaTrackVideo,pixel_width) },
     { MATROSKA_ID_VIDEOPIXELHEIGHT,   EBML_UINT, 0, offsetof(MatroskaTrackVideo,pixel_height) },
-    { MATROSKA_ID_VIDEOCOLORSPACE,    EBML_UINT, 0, offsetof(MatroskaTrackVideo,fourcc) },
+    { MATROSKA_ID_VIDEOCOLORSPACE,    EBML_BIN,  0, offsetof(MatroskaTrackVideo,color_space) },
     { MATROSKA_ID_VIDEOSTEREOMODE,    EBML_UINT, 0, offsetof(MatroskaTrackVideo,stereo_mode) },
     { MATROSKA_ID_VIDEOPIXELCROPB,    EBML_NONE },
     { MATROSKA_ID_VIDEOPIXELCROPT,    EBML_NONE },
@@ -1303,7 +1303,8 @@ 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;
+            if (track->video.color_space.size == 4)
+                fourcc = AV_RL32(track->video.color_space.data);
         } else if (track->type == MATROSKA_TRACK_TYPE_AUDIO) {
             if (!track->audio.out_samplerate)
                 track->audio.out_samplerate = track->audio.samplerate;