Follow these steps to compress a video file in Android mobile:
1. First of all, download Video Compressor app from Playstore and instal it on your mobile.
Link - https://play.google.com/store/apps/details?id=com.lkland.videocompressor&hl=en
2. Click on the "Input File" option and select the location of the video file.
3. Then, click on "Output Folder", and choose folder, where you would like to save the compressed file.
3. From the 3rd option, choose a name for the Output file.
4. Then, choose File size of the Output file. For example, if you current video is of 20 MB, then select 10 MB for better compression and quality.
5. At last, click on Convert button to start the process.