Videos which are converted with Ffmpeg do not play on mobile devices (iOS, Android)

Recommended Encoding Settings

1. For the greatest compatibility with a wide range of devices it is recommended to use -profile:v baseline -level 3.0
2. It is an idea to add -movflags +faststart if your file is going to be displayed online, with this setting it should start playback before fully downloaded
3. Use -pix_fmt yuv420p to allow playback on a wider range of devices