How to get frames from video and show with trimmer in react native like whatsapp status uploading

I'm developing a video streaming app and I need to trim, merge audio & video stuff like that, But for Now, I've to get frames of video and show in the trimmer so that user can trim the video as per his need. How can I achieve this? If anybody done this before please let me know, I'm going through the react-native-FFmpeg but it does not provide much documentation on how to do.