ExoPlayer 2 的质量选择器

我目前正在开发一个现场和电影播放器​​应用程序。我选择了Exo播放器版本2播放这部电影，我对此了解不多。我想让用户选择电影的质量在播放器屏幕上，例如 720p 或 1080p 等。 但我不知道如何获取现有品质的列表并将其显示给用户。 下面的代码是我对 SimpleExoPlayer 的实现：

private void initPlayer(String path){
    Handler handler = new Handler();
    // 1. Create a default TrackSelector
    BandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
    TrackSelection.Factory videoTrackSelectionFactory =
            new AdaptiveVideoTrackSelection.Factory(bandwidthMeter);
    TrackSelector trackSelector =
            new DefaultTrackSelector(videoTrackSelectionFactory);

    // 2. Create a default LoadControl
    LoadControl loadControl = new DefaultLoadControl();
    // 3. Create the player
    player = ExoPlayerFactory.newSimpleInstance(this, trackSelector, loadControl);

    SimpleExoPlayerView playerView = (SimpleExoPlayerView) findViewById(R.id.player_view);
    playerView.setPlayer(player);
    playerView.setKeepScreenOn(true);
    // Produces DataSource instances through which media data is loaded.
    DataSource.Factory dataSourceFactory = new DefaultDataSourceFactory(this, Util.getUserAgent(this, "ExoPlayer"));

    // This is the MediaSource representing the media to be played.
    MediaSource videoSource = new HlsMediaSource(Uri.parse(path),
            dataSourceFactory,handler, null);
    // Prepare the player with the source.
    player.addListener(this);
    player.prepare(videoSource);
    playerView.requestFocus();
    player.setPlayWhenReady(true); // to play video when ready. Use false to pause a video
}

// ExoPlayer Listener Methods :
@Override
public void onTimelineChanged(Timeline timeline, Object manifest) {

}

@Override
public void onTracksChanged(TrackGroupArray trackGroups, TrackSelectionArray trackSelections) {

}

@Override
public void onLoadingChanged(boolean isLoading) {

}

@Override
public void onPlayerStateChanged(boolean playWhenReady, int playbackState) {
    switch (playbackState) {
        case ExoPlayer.STATE_BUFFERING:
            //You can use progress dialog to show user that video is preparing or buffering so please wait
            progressBar.setVisibility(View.VISIBLE);
            break;
        case ExoPlayer.STATE_IDLE:
            //idle state
            break;
        case ExoPlayer.STATE_READY:
            // dismiss your dialog here because our video is ready to play now
            progressBar.setVisibility(GONE);
            //Toast.makeText(getApplicationContext(),String.valueOf(player.getCurrentTrackSelections().get(0).getSelectedFormat().bitrate),Toast.LENGTH_SHORT).show();
            break;
        case ExoPlayer.STATE_ENDED:
            // do your processing after ending of video
            break;
    }
}

@Override
public void onPlayerError(ExoPlaybackException error) {
    // show user that something went wrong. it can be a dialog
}

@Override
public void onPositionDiscontinuity() {

}

请帮助解决这个问题。 多谢。

您想要实现的一切都可以在 ExoPlayer2 中查看demo app https://github.com/google/ExoPlayer。更具体地说PlayerActivity https://github.com/google/ExoPlayer/blob/release-v2/demos/main/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java class.

你也可以看看这个好文章 https://medium.com/google-exoplayer/exoplayer-2-x-track-selection-2b62ff712cc9关于这个话题。

您需要研究的核心点是围绕曲目选择（通过TrackSelector）以及TrackSelectionHelper。我将在下面提供重要的代码示例，希望这些示例足以帮助您继续前进。但最终，只需遵循演示应用程序中类似的操作即可到达您需要的位置。

您将保留启动播放器时使用的曲目选择器，并将其用于几乎所有事情。

下面只是一段代码，理想地涵盖了您想要做的事情的要点，因为该演示似乎确实使事情变得过于复杂。我还没有运行代码，但它已经足够接近了。

// These two could be fields OR passed around
int videoRendererIndex;
TrackGroupArray trackGroups;

// This is the body of the logic for see if there are even video tracks
// It also does some field setting
MappedTrackInfo mappedTrackInfo = trackSelector.getCurrentMappedTrackInfo();
for (int i = 0; i < mappedTrackInfo.length; i++) {
  TrackGroupArray trackGroups = mappedTrackInfo.getTrackGroups(i);
  if (trackGroups.length != 0) {
    switch (player.getRendererType(i)) {
      case C.TRACK_TYPE_VIDEO:
        videoRendererIndex = i;
        return true;
    }
  }
}

// This next part is actually about getting the list. It doesn't include
// some additional logic they put in for adaptive tracks (DASH/HLS/SS),
// but you can look at the sample for that (TrackSelectionHelper#buildView())
// Below you'd be building up items in a list. This just does
// views directly, but you could just have a list of track names (with indexes)
for (int groupIndex = 0; groupIndex < trackGroups.length; groupIndex++) {
  TrackGroup group = trackGroups.get(groupIndex);
  for (int trackIndex = 0; trackIndex < group.length; trackIndex++) {
    if (trackIndex == 0) {
      // Beginning of a new set, the demo app adds a divider
    }
    CheckedTextView trackView = ...; // The TextView to show in the list
    // The below points to a util which extracts the quality from the TrackGroup
    trackView.setText(DemoUtil.buildTrackName(group.getFormat(trackIndex)));
}

// Assuming you tagged the view with the groupIndex and trackIndex, you
// can build your override with that info.
Pair<Integer, Integer> tag = (Pair<Integer, Integer>) view.getTag();
int groupIndex = tag.first;
int trackIndex = tag.second;
// This is the override you'd use for something that isn't adaptive.
override = new SelectionOverride(FIXED_FACTORY, groupIndex, trackIndex);
// Otherwise they call their helper for adaptives, which roughly does:
int[] tracks = getTracksAdding(override, trackIndex);
TrackSelection.Factory factory = tracks.length == 1 ? FIXED_FACTORY : adaptiveTrackSelectionFactory;
override = new SelectionOverride(factory, groupIndex, tracks);

// Then we actually set our override on the selector to switch the quality/track
selector.setSelectionOverride(rendererIndex, trackGroups, override);

正如我上面提到的，这个过程有点过于简单化，但核心部分是你在搞乱TrackSelector, SelectionOverride, and Track/TrackGroups让它发挥作用。

可以想象，您可以逐字复制演示代码，它应该可以工作，但我强烈建议花时间了解每个部分的作用，并根据您的用例定制您的解决方案。

如果我有更多时间，我会编译并运行它。但如果您可以使用我的示例，请随意编辑我的帖子。

希望有帮助:)