Using cache in ExoPlayer

I'm looking for any example of implementing cache in ExoPlayer.

ExoPlayer has in its library different classes concerning cache and Google explain in this video that we can implement it with the CacheDataSource class, but Google doesn't provide any demo on it. Unfortunately this seems pretty complicated to use, so I'm currently looking for examples (no success on Google).

Does anyone succeed or has any info that would help ? Thanks.

Here is the solution for ExoPlayer 2.+

Create a custom cache data source factory

public class CacheDataSourceFactory implements DataSource.Factory {
    private final Context context;
    private final DefaultDataSourceFactory defaultDatasourceFactory;
    private final long maxFileSize, maxCacheSize;

    public CacheDataSourceFactory(Context context, long maxCacheSize, long maxFileSize) {
        super();
        this.context = context;
        this.maxCacheSize = maxCacheSize;
        this.maxFileSize = maxFileSize;
        String userAgent = Util.getUserAgent(context, context.getString(R.string.app_name));
        DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
        defaultDatasourceFactory = new DefaultDataSourceFactory(this.context,
                bandwidthMeter,
                new DefaultHttpDataSourceFactory(userAgent, bandwidthMeter));
    }

    @Override
    public DataSource createDataSource() {
        LeastRecentlyUsedCacheEvictor evictor = new LeastRecentlyUsedCacheEvictor(maxCacheSize);
        SimpleCache simpleCache = new SimpleCache(new File(context.getCacheDir(), "media"), evictor);
        return new CacheDataSource(simpleCache, defaultDatasourceFactory.createDataSource(),
                new FileDataSource(), new CacheDataSink(simpleCache, maxFileSize),
                CacheDataSource.FLAG_BLOCK_ON_CACHE | CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR, null);
    }
}

And the player

BandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
TrackSelection.Factory videoTrackSelectionFactory =
        new AdaptiveTrackSelection.Factory(bandwidthMeter);
TrackSelector trackSelector = new DefaultTrackSelector(videoTrackSelectionFactory);

SimpleExoPlayer exoPlayer = ExoPlayerFactory.newSimpleInstance(this, trackSelector);
MediaSource audioSource = new ExtractorMediaSource(Uri.parse(url),
            new CacheDataSourceFactory(context, 100 * 1024 * 1024, 5 * 1024 * 1024), new DefaultExtractorsFactory(), null, null);
exoPlayer.setPlayWhenReady(true); 
exoPlayer.prepare(audioSource);

It works pretty well.

By default ExoPlayer do not cache media (video, audio, etc...). For example if you want to play an online video file, each time ExoPlayer will open a connection, read data then play it.

Fortunately, it provides us some interfaces and implementation classes to support caching media in our app.

You can write your own cache which implement given interfaces from ExoPlayer. To make it simple I will guide you how to enable cache by using implementation classes.

Step 1: Specify a folder which contains your media files, in Android for smaller cache folder (less than 1MB), you should use getCacheDir, otherwise you can specify your prefer cache folder, getFileDir for example.

Step 2: Specify a size for the cache folder, and policies when the size is reached out. There are 2 APIs

• NoOpCacheEvictor that doesn't ever evict/remove cache files. Based on location of your cache folder, if it's in internal storage, the folder will be removed when users clear app data or uninstall app.
• LeastRecentlyUsedCacheEvictor that will evict/remove least recently used cache files first. For example if your cache size is 10MB, when the size is reached out, it will automatically find and remove files which least recently used.

Put it together

val renderersFactory = DefaultRenderersFactory(context.applicationContext)
val trackSelector = DefaultTrackSelector()
val loadControl = DefaultLoadControl()

val player = ExoPlayerFactory.newSimpleInstance(context, renderersFactory, trackSelector, loadControl)
player.addListener(this)

// Specify cache folder, my cache folder named media which is inside getCacheDir.
val cacheFolder = File(context.cacheDir, "media")

// Specify cache size and removing policies
val cacheEvictor = LeastRecentlyUsedCacheEvictor(1 * 1024 * 1024) // My cache size will be 1MB and it will automatically remove least recently used files if the size is reached out.

// Build cache
val cache = SimpleCache(cacheFolder, cacheEvictor)

// Build data source factory with cache enabled, if data is available in cache it will return immediately, otherwise it will open a new connection to get the data.
val cacheDataSourceFactory = CacheDataSourceFactory(cache, DefaultHttpDataSourceFactory("ExoplayerDemo"))

val uri = Uri.parse("Put your media url here")
val mediaSource = ExtractorMediaSource.Factory(cacheDataSourceFactory).createMediaSource(uri)

player.prepare(mediaSource)

I answered this similar question here: https://stackoverflow.com/a/58678192/2029134

Basically, I use this library: https://github.com/danikula/AndroidVideoCache To cache file from URL Then put it in ExoPlayer.

Here is the sample code:

String mediaURL = "https://my_cool_vid.com/vi.mp4";
SimpleExoPlayer exoPlayer = ExoPlayerFactory.newSimpleInstance(getContext());
HttpProxyCacheServer proxyServer = HttpProxyCacheServer.Builder(getContext()).maxCacheSize(1024 * 1024 * 1024).build();

String proxyURL = proxyServer.getProxyUrl(mediaURL);


DataSource.Factory dataSourceFactory = new DefaultDataSourceFactory(getContext(),
                Util.getUserAgent(getContext(), getActivity().getApplicationContext().getPackageName()));


exoPlayer.prepare(new ProgressiveMediaSource.Factory(dataSourceFactory)
                .createMediaSource(Uri.parse(proxyURL)););

Hope that helps.

To resolve the problem of multiple videos or processes trying to access the same cache, you need a true Singleton. A reliable way would be to do it this way:

object VideoCache {
    private var sDownloadCache: SimpleCache? = null
    private const val maxCacheSize: Long = 100 * 1024 * 1024

    fun getInstance(context: Context): SimpleCache {
        val evictor = LeastRecentlyUsedCacheEvictor(maxCacheSize)
        if (sDownloadCache == null) sDownloadCache = SimpleCache(File(context.cacheDir, "koko-media"), evictor)
        return sDownloadCache as SimpleCache
    }
}

which you can now use:

private val simpleCache: SimpleCache by lazy {
        VideoCache.getInstance(context)
    }

Here is an example which replaces demo data source with OkHttp, default is no cache https://github.com/b95505017/ExoPlayer/commit/ebfdda8e7848a2e2e275f5c0525f614b56ef43a6 https://github.com/b95505017/ExoPlayer/tree/okhttp_http_data_source So, you just need to configure OkHttp cache properly and requests should be cached.

I've implemented it like this in the renderer builder

private static final int BUFFER_SEGMENT_SIZE = 64 * 1024;
private static final int BUFFER_SEGMENT_COUNT = 160;

final String userAgent = Util.getUserAgent(mContext, appName);
final DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
final Allocator allocator = new DefaultAllocator(BUFFER_SEGMENT_SIZE);*

Cache cache = new SimpleCache(context.getCacheDir(), new LeastRecentlyUsedCacheEvictor(1024 * 1024 * 10));
DataSource dataSource = new DefaultUriDataSource(context, bandwidthMeter, userAgent);
CacheDataSource cacheDataSource = new CacheDataSource(cache, dataSource, false, false);
ExtractorSampleSource sampleSource = new ExtractorSampleSource(uri
                , cacheDataSource
                , allocator
                , BUFFER_SEGMENT_COUNT * BUFFER_SEGMENT_SIZE
                , new Mp4Extractor());

In addition to Bao Le's answer, here's ready to use Kotlin version of CacheDataSourceFactory that keeps one instance of SimpleCache to solve the problem of multiple Cache objects writing to the same directory.

class CacheDataSourceFactory(private val context: Context,
                                      private val maxCacheSize: Long,
                                      private val maxFileSize: Long) : DataSource.Factory {

    private val defaultDatasourceFactory: DefaultDataSourceFactory
    private val simpleCache: SimpleCache by lazy {
        val evictor = LeastRecentlyUsedCacheEvictor(maxCacheSize)
        SimpleCache(File(context.cacheDir, "media"), evictor)
    }

    init {
        val userAgent = Util.getUserAgent(context, context.packageName)
        val bandwidthMeter = DefaultBandwidthMeter()
        defaultDatasourceFactory = DefaultDataSourceFactory(context,
                bandwidthMeter,
                DefaultHttpDataSourceFactory(userAgent, bandwidthMeter))
    }

    override fun createDataSource(): DataSource {
        return CacheDataSource(simpleCache,
                defaultDatasourceFactory.createDataSource(),
                FileDataSource(),
                CacheDataSink(simpleCache, maxFileSize),
                CacheDataSource.FLAG_BLOCK_ON_CACHE or CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR,
                null)
    }
}

Here's my sample in Kotlin (project available here) :

class MainActivity : AppCompatActivity() {
    private var player: SimpleExoPlayer? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        if (cache == null) {
            cache = SimpleCache(File(cacheDir, "media"), LeastRecentlyUsedCacheEvictor(MAX_PREVIEW_CACHE_SIZE_IN_BYTES))
        }
        setContentView(R.layout.activity_main)
    }

    override fun onStart() {
        super.onStart()
        playVideo()
    }

    private fun playVideo() {
        player = ExoPlayerFactory.newSimpleInstance(this@MainActivity, DefaultTrackSelector())
        playerView.player = player
        player!!.volume = 1f
        player!!.playWhenReady = true
        player!!.repeatMode = Player.REPEAT_MODE_ALL
        player!!.playVideoFromUrl(this, "https://sample-videos.com/video123/mkv/240/big_buck_bunny_240p_20mb.mkv", cache!!)
//        player!!.playVideoFromUrl(this, "https://sample-videos.com/video123/mkv/720/big_buck_bunny_720p_1mb.mkv", cache!!)
//        player!!.playVideoFromUrl(this, "https://sample-videos.com/video123/mkv/720/big_buck_bunny_720p_1mb.mkv")
//        player!!.playRawVideo(this,R.raw.videoplayback)
    }

    override fun onStop() {
        super.onStop()
        playerView.player = null
        player!!.release()
        player = null
    }

    companion object {
        const val MAX_PREVIEW_CACHE_SIZE_IN_BYTES = 20L * 1024L * 1024L
        var cache: com.google.android.exoplayer2.upstream.cache.Cache? = null

        @JvmStatic
        fun getUserAgent(context: Context): String {
            val packageManager = context.packageManager
            val info = packageManager.getPackageInfo(context.packageName, 0)
            val appName = info.applicationInfo.loadLabel(packageManager).toString()
            return Util.getUserAgent(context, appName)
        }
    }

    fun SimpleExoPlayer.playRawVideo(context: Context, @RawRes rawVideoRes: Int) {
        val dataSpec = DataSpec(RawResourceDataSource.buildRawResourceUri(rawVideoRes))
        val rawResourceDataSource = RawResourceDataSource(context)
        rawResourceDataSource.open(dataSpec)
        val factory: DataSource.Factory = DataSource.Factory { rawResourceDataSource }
        prepare(LoopingMediaSource(ExtractorMediaSource.Factory(factory).createMediaSource(rawResourceDataSource.uri)))
    }

    fun SimpleExoPlayer.playVideoFromUrl(context: Context, url: String, cache: Cache? = null) = playVideoFromUri(context, Uri.parse(url), cache)

    fun SimpleExoPlayer.playVideoFile(context: Context, file: File) = playVideoFromUri(context, Uri.fromFile(file))

    fun SimpleExoPlayer.playVideoFromUri(context: Context, uri: Uri, cache: Cache? = null) {
        val factory = if (cache != null)
            CacheDataSourceFactory(cache, DefaultHttpDataSourceFactory(getUserAgent(context)))
        else
            DefaultDataSourceFactory(context, MainActivity.getUserAgent(context))
        val mediaSource = ExtractorMediaSource.Factory(factory).createMediaSource(uri)
        prepare(mediaSource)
    }
}

Exoplayer's documentation list's the class DashDownloader and has some example code for that type of source. (Click [Frames] to get back navigation of the documentation. I had to remove it to get the deep link.)

SimpleCache simpleCache = new SimpleCache(new File(context.getCacheDir(), "media/"+id), evictor);

Here, id must be unique.