demux_mkv: add support for HEVC

Note that you still need --vd-lavc-o='strict=-2' to enable the decoder.

Also, there's no guarantee that all required features for HEVC demuxing
are actually implemented, nor that the current muxing schema is the
final one.

demux/codec_tags.c

@@ -313,6 +313,7 @@ static const struct mp_codec_tag mp_video_codec_tags[] = {
     {MKTAG('C', '9', '3', 'V'), "c93"},
     {MKTAG('V', 'P', '9', '0'), "vp9"},
     {MKTAG('p', 'r', '0', '0'), "prores"},
+    {MKTAG('H', 'E', 'V', 'C'), "hevc"},
     {0},
 };
 

demux/demux_mkv.c

@@ -1169,6 +1169,7 @@ static const videocodec_info_t vinfo[] = {
     {MKV_V_VP9,       mmioFOURCC('V', 'P', '9', '0'), 0},
     {MKV_V_DIRAC,     mmioFOURCC('d', 'r', 'a', 'c'), 0},
     {MKV_V_PRORES,    mmioFOURCC('p', 'r', '0', '0'), 0},
+    {MKV_V_HEVC,      mmioFOURCC('H', 'E', 'V', 'C'), 1},
     {NULL, 0, 0}
 };
 

demux/matroska.h

@@ -80,6 +80,8 @@
 #define MKV_V_UNCOMPRESSED "V_UNCOMPRESSED"
 #define MKV_V_DIRAC      "V_DIRAC"
 #define MKV_V_PRORES     "V_PRORES"
+#define MKV_V_PRORES     "V_PRORES"
+#define MKV_V_HEVC       "V_MPEGH/ISO/HEVC"
 
 #define MKV_S_TEXTASCII  "S_TEXT/ASCII"
 #define MKV_S_TEXTUTF8   "S_TEXT/UTF8"