Retrieve metadata

The MetadataRetriever retrieves information (such as duration, video resolution, codecs, available tracks, and sampling rates) from a MediaItem without playback.

Common use cases include:

  • Retrieving motion photo metadata: including the offsets and lengths of the image and video parts of the file.
  • Building a media library: Populating a MediaLibraryService with rich MediaItem details (like duration and title) to serve a full media catalog to clients like Android Auto.
  • Prefetching UI details: Fetching information like video resolution or duration to prepare the UI before playback begins.
  • Validating media files: Checking if a file contains the required audio or video tracks or specific metadata before processing it.

Overview

Using MetadataRetriever is a two-step process:

  1. Build the retriever: Create an instance using MetadataRetriever.Builder. Pass a Context and the MediaItem that you want to inspect to the builder. For advanced use cases, such as custom networking or caching, you can also supply a custom MediaSource.Factory.
  2. Retrieve metadata: Call methods like retrieveDurationUs(), retrieveTimeline(), or retrieveTrackGroups() to fetch the required information. These methods are asynchronous, returning a ListenableFuture so that network or I/O operations don't block the main thread.

Kotlin

suspend fun retrieveMetadata(context: Context, mediaItem: MediaItem) {
  try {
    // 1. Build the retriever.
    // `MetadataRetriever` implements `AutoCloseable`, so wrap it in
    // a Kotlin `.use` block, which calls `close()` automatically.
    MetadataRetriever.Builder(context, mediaItem).build().use { retriever ->
      // 2. Retrieve metadata asynchronously.
      val trackGroups = retriever.retrieveTrackGroups().await()
      val timeline = retriever.retrieveTimeline().await()
      val durationUs = retriever.retrieveDurationUs().await()
      handleMetadata(trackGroups, timeline, durationUs)
    }
  } catch (e: Exception) {
    handleFailure(e)
  }
}

RetrieveMetadata.kt

Java

public void retrieveMetadata(Context context, MediaItem mediaItem) {
  // 1. Build the retriever.
  // `MetadataRetriever` implements `AutoCloseable`, so use try-with-resources
  // so that the resources are automatically released.
  try (MetadataRetriever retriever = new MetadataRetriever.Builder(context, mediaItem).build()) {
    // 2. Retrieve metadata asynchronously.
    ListenableFuture<TrackGroupArray> trackGroupsFuture = retriever.retrieveTrackGroups();
    ListenableFuture<Timeline> timelineFuture = retriever.retrieveTimeline();
    ListenableFuture<Long> durationUsFuture = retriever.retrieveDurationUs();

    ListenableFuture<List<Object>> allFutures =
        Futures.allAsList(trackGroupsFuture, timelineFuture, durationUsFuture);
    Futures.addCallback(
        allFutures,
        new FutureCallback<List<Object>>() {
          @Override
          public void onSuccess(List<Object> result) {
            handleMetadata(
                Futures.getUnchecked(trackGroupsFuture),
                Futures.getUnchecked(timelineFuture),
                Futures.getUnchecked(durationUsFuture));
          }

          @Override
          public void onFailure(Throwable t) {
            handleFailure(t);
          }
        },
        directExecutor());
  }
}

RetrieveMetadata.java