Hello everyone,
I have been struggling with this for a long time.

I have a video of about 20 seconds which I want to be played in loop with an Audio track from the beginning to end.
Now the Audio file is about 1 hour long. So, just copying and pasting the video throughout the entire timeline is a hard task.

Is there any other way out?? Please, help me.

Please someone help me out.

Your details are rather sketchy but I'll take a stab at it.

I assume you have your 20 second long clip in the Project Bin. Select the clip and simply press V, again and again, until you fill your one hour Timeline. I know of no way to automate this in Kdenlive. For a one-off project it shouldn't be too hard. If you need to do this with other projects then I suggest using FFmpeg in the Terminal where you can write a shell script for automation.

-=Ken=-