how to delete the screen and leave only sound?

[kenny1999]

I have a video that I want to delete its screen but leave only the sound, but at the end of the day it should still be in video format... not a mp3 or mp4 or other sound format

probably everything becomes black or any other color , not a problem

How can I make it?
Looking for easy method please...

[butterw]

mp4 is a video format.
It can be done with ffmpeg.

What's the input format / audio codec ?

[jagabo]

There are many ways one could do this. Using ffmpeg you could make all the frames black and reencode them:

ffmpeg -i input.mkv -vf lutyuv="y=16:u=128:v=128" -c:v libx264 -preset ultrafast -c:a copy black.mkv

The black video will have the same frame size and frame rate but since all black frames compress very well the final file won't be much larger than just the audio stream.

You could also scale the frame smaller for faster encoding and a smaller window on playback:

ffmpeg -i input.mkv -vf scale=32:16,lutyuv="y=16:u=128:v=128" -c:v libx264 -preset ultrafast -c:a copy black.mkv

That creates a video that 32x16 pixels at the same frame rate as the source. I didn't time the conversion but a 90 minute movie took about a minute. The original movie was 1.4 GB, the resulting mkv was 128 MB. The audio data alone was 124 MB.