Range selector / range seekbar to trim video including thumbnails

I couldn't find a specific library, but you could use the MediaMetadataRetriever to get the frames for the video specifying the exact time of the frame.

MediaMetadataRetriever retriever = new MediaMetadataRetriever();
retriever.setDataSource(videoFile.getAbsolutePath());
Bitmap bitmap = retriever.getFrameAtTime(timeInMiliSeconds * 1000,
                MediaMetadataRetriever.OPTION_CLOSEST_SYNC);

I hope this helps you.

You can get the UI from TELEGRAM (messaging app) source code available at GitHub https://github.com/DrKLO/Telegram

Activity: VideoEditorActivity.java (https://github.com/DrKLO/Telegram/blob/master/TMessagesProj/src/main/java/org/telegram/ui/VideoEditorActivity.java)

Layout: video_editor_layout.xml (https://github.com/DrKLO/Telegram/blob/master/TMessagesProj/src/main/res/layout/video_editor_layout.xml)

They have implemented their custom UI components VideoSeekBarView and VideoTimelineView.

VideoSeekBarView (https://github.com/DrKLO/Telegram/blob/master/TMessagesProj/src/main/java/org/telegram/ui/Components/VideoSeekBarView.java)

VideoTimelineView (https://github.com/DrKLO/Telegram/blob/master/TMessagesProj/src/main/java/org/telegram/ui/Components/VideoTimelineView.java)

Attached is the Telegram VideoEditorActivity