avformat/matroskadec: support parsing Chroma Location elements

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/matroska.h

@@ -317,6 +317,20 @@ typedef enum {
   MATROSKA_VIDEO_DISPLAYUNIT_UNKNOWN     = 4,
 } MatroskaVideoDisplayUnit;
 
+typedef enum {
+  MATROSKA_COLOUR_CHROMASITINGHORZ_UNDETERMINED     = 0,
+  MATROSKA_COLOUR_CHROMASITINGHORZ_LEFT             = 1,
+  MATROSKA_COLOUR_CHROMASITINGHORZ_HALF             = 2,
+  MATROSKA_COLOUR_CHROMASITINGHORZ_NB
+} MatroskaColourChromaSitingHorz;
+
+typedef enum {
+  MATROSKA_COLOUR_CHROMASITINGVERT_UNDETERMINED     = 0,
+  MATROSKA_COLOUR_CHROMASITINGVERT_TOP              = 1,
+  MATROSKA_COLOUR_CHROMASITINGVERT_HALF             = 2,
+  MATROSKA_COLOUR_CHROMASITINGVERT_NB
+} MatroskaColourChromaSitingVert;
+
 /*
  * Matroska Codec IDs, strings
  */

libavformat/matroskadec.c

@@ -1827,6 +1827,14 @@ static int mkv_parse_video_color(AVStream *st, const MatroskaTrack *track) {
     if (track->video.color.range != AVCOL_RANGE_UNSPECIFIED &&
         track->video.color.range <= AVCOL_RANGE_JPEG)
         st->codecpar->color_range = track->video.color.range;
+    if (track->video.color.chroma_siting_horz != MATROSKA_COLOUR_CHROMASITINGHORZ_UNDETERMINED &&
+        track->video.color.chroma_siting_vert != MATROSKA_COLOUR_CHROMASITINGVERT_UNDETERMINED &&
+        track->video.color.chroma_siting_horz  < MATROSKA_COLOUR_CHROMASITINGHORZ_NB &&
+        track->video.color.chroma_siting_vert  < MATROSKA_COLOUR_CHROMASITINGVERT_NB) {
+        st->codecpar->chroma_location =
+            avcodec_chroma_pos_to_enum((track->video.color.chroma_siting_horz - 1) << 7,
+                                       (track->video.color.chroma_siting_vert - 1) << 7);
+    }
 
     if (has_mastering_primaries || has_mastering_luminance) {
         // Use similar rationals as other standards.