I'm working on a project that use Exoplayer2 for HLS video streaming. Adaptive streaming is working well in my exoplayer, but i want to implement a feature that user can change the resolution (144p,240p,480p..)of the video manually from UI. I got the resolution of the playing video from TrackGroup API. But don't know how to set the resolution value into the playing video manually. Thanks
You can do this using the track selector functionality in Exoplayer2 - it essentially limits the tracks that the adaptive bit rate selection functionality in the player can select from.
It can only select from the available tracks in the stream index file, the manifest file. Hence, your choice of resolutions/bit rates is limited to whatever bitrate, resolution etc the stream provider has made available - i.e. the user can't just choose an arbitrary bit rate or resolution that they would like, if it is not one of the available ones in the manifest file (the video track index file).
To have just one track you simply only allow that one.
This functionality is included in the demo - here is an example screen shot from one of their blogs about this:
More details specifically on track selection here (it is also linked from the Exoplyar GitHub page): https://medium.com/google-exoplayer/exoplayer-2-x-track-selection-2b62ff712cc9
来源：https://stackoverflow.com/questions/44061924/is-it-possible-to-change-resolution-of-exoplayer-manually