requested to merge elliot_chen/gstreamer:dashdemux2-support-adaptive-playback-for-webm-stream into main
- Currently, dashdemux2 will play with fixed bitrate for webm stream and can't change presentation of it according the actual bitrate.
- The patch can detect and parse matroska stream. And change presentation index according to the current bitrate after every subfragment.
- The test webm stream: https://storage.googleapis.com/shaka-demo-assets/sintel-webm-only/dash.mpd