Exoplayer 自适应 HLS 流媒体播放

Question

Exoplayer 自适应 HLS 流媒体播放

androidhttp-live-streamingexoplayeradaptive-bitrate

11

我正在寻找一个好的简单示例/解释，如何实现使用ExoPlayer进行HLS自适应流媒体传输。我是新手，没有经验和知识，所以无法从git上的代码示例中理解如何执行此操作。

有太多的“移动部件”，使初学者可以理解并在自己的项目中重复使用它。

能否有人帮助我学习和理解如何使用/实现ExoPlayer以实现此功能？

谢谢！

- svarog

2个回答

3

@Vicky的回答是可行的，但有一个缺陷。

你传递给轨道选择器的带宽计量器必须与数据源工厂使用的计量器相同。数据源工厂通过调用BW计量器方法来维护带宽估计值，自适应轨道选择过程获取该估计值以决定要自适应哪个轨道。

如果它们不是同一实例，则自适应选项始终获得-1作为BW，并选择一些中间地带的选项。

演示ExoPlayer应用程序也有此缺陷。他们在buildDataSource()中将useBwMeter设置为false，这意味着不更新BW估计值。编辑：实际上，这个BW计量器是用于清单加载器的，它不需要使用BW计量器。

- Darren

Exo Player 是否支持 RTMP 自适应流媒体播放？ - Nitish

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Vicky · Accepted Answer

使用ExoPlayer的最简单方法是将其作为Gradle依赖项添加。您需要确保在项目根目录中的build.gradle文件中包含jcenter存储库：

repositories { jcenter() }

接下来，在您的模块的build.gradle文件中包含以下内容：

compile 'com.google.android.exoplayer:exoplayer:r2.2.0'

1. 您的布局文件

    <?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    android:id="@+id/activity_main"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.exoplayer2.ui.SimpleExoPlayerView
        android:id="@+id/player_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:focusable="true"
        app:resize_mode="fill"/>

    <ProgressBar
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:visibility="gone"/>

</FrameLayout>

2. 您的类文件（Activity）

    public class VideoPlayerActivity extends AppCompatActivity implements ExoPlayer.EventListener {

    private SimpleExoPlayerView simpleExoPlayerView;
    private String hlsVideoUri = "http://playertest.longtailvideo.com/adaptive/bbbfull/bbbfull.m3u8";
    private SimpleExoPlayer player;
    private ProgressBar progressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_video_player);

        // 1. Create a default TrackSelector
        Handler mainHandler = new Handler();
        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 = (SimpleExoPlayerView) findViewById(R.id.player_view);
        simpleExoPlayerView.setPlayer(player);

        // Measures bandwidth during playback. Can be null if not required.
        DefaultBandwidthMeter defaultBandwidthMeter = new DefaultBandwidthMeter();
        // Produces DataSource instances through which media data is loaded.
        DataSource.Factory dataSourceFactory = new DefaultDataSourceFactory(this,
                Util.getUserAgent(this, "Exo2"), defaultBandwidthMeter);
        // Produces Extractor instances for parsing the media data.
        ExtractorsFactory extractorsFactory = new DefaultExtractorsFactory();
        // This is the MediaSource representing the media to be played.
        HlsMediaSource hlsMediaSource = new HlsMediaSource(Uri.parse(hlsVideoUri), dataSourceFactory, mainHandler, new AdaptiveMediaSourceEventListener() {
            @Override
            public void onLoadStarted(DataSpec dataSpec, int dataType, int trackType, Format trackFormat, int trackSelectionReason, Object trackSelectionData, long mediaStartTimeMs, long mediaEndTimeMs, long elapsedRealtimeMs) {

            }

            @Override
            public void onLoadCompleted(DataSpec dataSpec, int dataType, int trackType, Format trackFormat, int trackSelectionReason, Object trackSelectionData, long mediaStartTimeMs, long mediaEndTimeMs, long elapsedRealtimeMs, long loadDurationMs, long bytesLoaded) {

            }

            @Override
            public void onLoadCanceled(DataSpec dataSpec, int dataType, int trackType, Format trackFormat, int trackSelectionReason, Object trackSelectionData, long mediaStartTimeMs, long mediaEndTimeMs, long elapsedRealtimeMs, long loadDurationMs, long bytesLoaded) {

            }

            @Override
            public void onLoadError(DataSpec dataSpec, int dataType, int trackType, Format trackFormat, int trackSelectionReason, Object trackSelectionData, long mediaStartTimeMs, long mediaEndTimeMs, long elapsedRealtimeMs, long loadDurationMs, long bytesLoaded, IOException error, boolean wasCanceled) {

            }

            @Override
            public void onUpstreamDiscarded(int trackType, long mediaStartTimeMs, long mediaEndTimeMs) {

            }

            @Override
            public void onDownstreamFormatChanged(int trackType, Format trackFormat, int trackSelectionReason, Object trackSelectionData, long mediaTimeMs) {

            }
        });

        player.addListener(this);
        player.prepare(hlsMediaSource);
        simpleExoPlayerView.requestFocus();
        player.setPlayWhenReady(true);

        progressBar = (ProgressBar) findViewById(R.id.progressBar);
    }

    @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 Player.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 Player.STATE_IDLE:
                //idle state
                break;
            case Player.STATE_READY:
                // dismiss your dialog here because our video is ready to play now
                progressBar.setVisibility(View.GONE);
                break;
            case Player.STATE_ENDED:
                // do your processing after ending of video
                break;
        }
    }

    @Override
    public void onPlayerError(ExoPlaybackException error) {

        AlertDialog.Builder adb = new AlertDialog.Builder(VideoPlayerActivity.this);
        adb.setTitle("Could not able to stream video");
        adb.setMessage("It seems that something is going wrong.\nPlease try again.");
        adb.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                finish(); // take out user from this activity. you can skip this
            }
        });
        AlertDialog ad = adb.create();
        ad.show();
    }

    @Override
    public void onPositionDiscontinuity() {

    }

    @Override
    protected void onPause() {
        super.onPause();
        if (player != null) {
            player.setPlayWhenReady(false); //to pause a video because now our video player is not in focus
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        player.release();
    }
}

我认为这已经足够让初学者使用了。同时请记住，此库的标准音频和视频组件依赖于Android的MediaCodec API，该API在Android 4.1（API级别16）中发布。因此，在Android 4.0及以下版本上无法正常工作。

不要忘记将此权限添加到清单文件中：

<uses-permission android:name="android.permission.INTERNET"/>