Add VP9 support in mkv

Close #9341

modules/codec/avcodec/fourcc.c

@@ -184,6 +184,7 @@ static const struct
     { VLC_CODEC_INDEO5, AV_CODEC_ID_INDEO5, VIDEO_ES },
 
     { VLC_CODEC_VP8, AV_CODEC_ID_VP8, VIDEO_ES },
+    { VLC_CODEC_VP9, AV_CODEC_ID_VP9, VIDEO_ES },
 
     { VLC_CODEC_LAGARITH, AV_CODEC_ID_LAGARITH, VIDEO_ES },
 

modules/demux/mkv/matroska_segment_parse.cpp

@@ -1349,6 +1349,11 @@ int32_t matroska_segment_c::TrackInit( mkv_track_t * p_tk )
         p_tk->fmt.i_codec = VLC_CODEC_VP8;
         p_tk->b_pts_only = true;
     }
+    else if( !strncmp( p_tk->psz_codec, "V_VP9", 5 ) )
+    {
+        p_tk->fmt.i_codec = VLC_CODEC_VP9;
+        fill_extra_data( p_tk, 0 );
+    }
     else if( !strncmp( p_tk->psz_codec, "V_MPEG4", 7 ) )
     {
         if( !strcmp( p_tk->psz_codec, "V_MPEG4/MS/V3" ) )