Extract video frames

The FrameExtractor class provides an efficient way to extract decoded frames from a MediaItem.

Common use cases include:

  • Generating thumbnails: Creating high-quality thumbnails for a video gallery or seek bar.
  • Video editing previews: Displaying precise frame previews in an editor timeline, allowing users to seek through the content and visualize frames accurately.
  • Applying transformations like scaling, cropping, or rotation directly during extraction, avoiding a separate post-processing step.
  • Content analysis: Extracting frames at intervals to send to an analysis pipeline for tasks like scene detection, object recognition, or quality control.

Overview

Using FrameExtractor is a two-step process:

  1. Build the extractor: Create an instance using FrameExtractor.Builder. Pass a Context and the MediaItem that you want to inspect to the builder. You can also chain configuration methods on the Builder for advanced settings.
  2. Extract frames: Call getFrame() to extract a frame at a specific timestamp or getThumbnail() to request a representative thumbnail. These methods are asynchronous and return a ListenableFuture. Hence, the complex decoding work doesn't block the main thread.

Kotlin

suspend fun extractFrames(context: Context, mediaItem: MediaItem) {
  try {
    // 1. Build the frame extractor.
    // `FrameExtractor` implements `AutoCloseable`, so wrap it in
    // a Kotlin `.use` block, which calls `close()` automatically.
    FrameExtractor.Builder(context, mediaItem).build().use { extractor ->
      // 2. Extract frames asynchronously.
      val frame = extractor.getFrame(5000L).await()
      val thumbnail = extractor.thumbnail.await()
      handleFrame(frame, thumbnail)
    }
  } catch (e: Exception) {
    handleFailure(e)
  }
}

ExtractFrames.kt

Java

public void extractFrames(Context context, MediaItem mediaItem) {
  // 1. Build the frame extractor.
  // `FrameExtractor` implements `AutoCloseable`, so use try-with-resources
  // so that the resources are automatically released.
  try (FrameExtractor frameExtractor = new FrameExtractor.Builder(context, mediaItem).build()) {
    // 2. Extract frames asynchronously.
    ListenableFuture<FrameExtractor.Frame> frameFuture = frameExtractor.getFrame(5000L);
    ListenableFuture<FrameExtractor.Frame> thumbnailFuture = frameExtractor.getThumbnail();

    ListenableFuture<List<Object>> allFutures = Futures.allAsList(frameFuture, thumbnailFuture);
    Futures.addCallback(
        allFutures,
        new FutureCallback<List<Object>>() {
          @Override
          public void onSuccess(List<Object> result) {
            handleFrame(Futures.getUnchecked(frameFuture), Futures.getUnchecked(thumbnailFuture));
          }

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

ExtractFrames.java