Loop video for the duration of audio

Question

I have a 10 seconds video clip and 60 seconds audio clip, so when I mux it with

mkvmerge --output video.mkv ./a.mp3 ./a.mp4

The output file shows the video only for the first 10 seconds, and then the last frame is displayed for 50 seconds.

How can I loop the video in automatic mode so that it repeats for the whole 60 seconds with mkvmerge or any other command line tool (I need to automate it as I have to do it for 400 files)?

Answer 1

To merge an audio stream with a repeated video stream

ffmpeg -stream_loop -1 -i 20s.ts -i 120s.mp3 -map 0:v:0 -map 1:a:0 -shortest -c copy output.mp4

• -stream_loop -1 : to loop infinity of video input stream
• -map 0:v:0 : pick the video of the first input stream
• -map 1:a:0 : pick the audio of the second input stream
• -shortest : select the shortest length of input streams, which is the audio stream since the video will be looped infinity
• -c copy : no video and audio transcodes.