ffmpeg overlay one video on another and only keep sound of overlay video

Question

with code below I can overlay two video ffmpeg -i file.mp4 -i ppt.mp4 -filter_complex "[0]scale=700:-1 [overlay]; [1][overlay] overlay=main_w - overlay_w:main_h - overlay_h " -map 1:a -c:a copy output.mp4 However I only want too keep the audio of file.mp4(overlay video) what should I do?

Answer 1

Map the first input's audio instead.

ffmpeg -i file.mp4 -i ppt.mp4 -filter_complex "[0]scale=700:-1 [overlay]; [1][overlay] overlay=main_w - overlay_w:main_h - overlay_h " -map 0:a -c:a copy output.mp4