lavf/matroska: Add functions for WebM DASH Manifest

Add functions and logic to matroskadec for use by the WebM DASH Manifest
XML Muxer. The actual muxer is added in a future patch.
Signed-off-by: Vignesh Venkatasubramanian <vigneshv@google.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/matroska.h

@@ -284,4 +284,16 @@ extern const AVMetadataConv ff_mkv_metadata_conv[];
 extern const char * const ff_matroska_video_stereo_mode[MATROSKA_VIDEO_STEREO_MODE_COUNT];
 extern const char * const ff_matroska_video_stereo_plane[MATROSKA_VIDEO_STEREO_PLANE_COUNT];
 
+/* AVStream Metadata tag keys for WebM Dash Manifest */
+#define INITIALIZATION_RANGE "webm_dash_manifest_initialization_range"
+#define CUES_START "webm_dash_manifest_cues_start"
+#define CUES_END "webm_dash_manifest_cues_end"
+#define FILENAME "webm_dash_manifest_file_name"
+#define BANDWIDTH "webm_dash_manifest_bandwidth"
+#define DURATION "webm_dash_manifest_duration"
+#define CLUSTER_KEYFRAME "webm_dash_manifest_cluster_keyframe"
+#define CUE_TIMESTAMPS "webm_dash_manifest_cue_timestamps"
+#define TRACK_NUMBER "webm_dash_manifest_track_number"
+#define CODEC_PRIVATE_SIZE "webm_dash_manifest_codec_priv_size"
+
 #endif /* AVFORMAT_MATROSKA_H */