If you already use ExoPlayer in your project and need to extract video frames and show them as a timeline view either scrollable or in a fixed-width mode then you're in the right place.

You might already be familiar with MediaMetadataRetriever api and its getFrameAtTime(..) method, I included adapter implementation(it's not meant for production use) for comparison with RetroInstance API, which caches frames internally and won't init any mediaCodec resource if unnecessary. And it's running significantly faster.

Add this to your application module, inside dependencies block.

dependencies {
    implementation 'com.chemicalbird.android:videotimelineview:0.0.4'
}

1. For fixed frame list there is already an implementation of GLSurfaceView that you can use out of the box. Your layout and code goes like this.

<com.video.timeline.render.TimelineGlSurfaceView
        android:id="@+id/fixed_thumb_list"
        android:layout_width="match_parent"
        android:layout_height="68dp"
        />

VideoTimeLine.with(fileUri).show(glSurfaceView);

2. To create a frame grabber MediaRetriever implementation use RetroInstance, for example pass it to your RecyclerView.Adapter. To get a frame at specific time call retroInstance.load(presentationTime, callback). Checkout Sample project for more details.

RetroInstance retroInstance = new RetroInstance.Builder(context, mediaUri).setFrameSizeDp(180).create();
    
// in adapter
retroInstance.load(position * frameDuration, holder.hashCode(),
                file -> imageLoader.load(file, imageView));