Video Production Stack Exchange is a question and answer site for engineers, producers, editors, and enthusiasts spanning the fields of video, and media creation. It only takes a minute to sign up.
Sign up to join this community
I want to make a video play at 75% speed, so I used the following command:
ffmpeg -i combinedfullspeed.mp4 \
-filter_complex "[0:v]setpts=1.25*PTS[v];[0:a]atempo=0.75[a]" \
-map "[v]" -map "[a]" slow3.mp4
However, the video and audio are way out of sync. Any idea why?
The reciprocal of 75% i.e. 0.75 is 4/3 or 1.3333, so
ffmpeg -i combinedfullspeed.mp4 -filter_complex "[0:v]setpts=(4/3)*PTS[v];[0:a]atempo=0.75[a]" -map "[v]" -map "[a]" slow3.mp4
