You have downloaded some MP4 or MKV video files.
You want to extract audio parts so that you could copy them to your iPhone to listen to them while turning off the display of your phone.
- Download this portable application to your Windows.
- Open the application.
- Click on the Add files button to add MP4 or MKV files to the application.
- If you want to extract the original audio (for example the M4A format) then select Try extract original audio stream option below the Audio section on the right panel.
- Click the Convert button.
- Copy the MP3 or M4A files to your phone.