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Modify image and sound speed
The projection or viewing speed of an audio-visual file should be changed from 24 fps (which is the cinema standard) to 25 fps (which is the «European» television standard).
ffmpeg \ -i input_file \ -r 25 \ -filter_complex \ "[0:v]setpts=24/25*PTS[v]; \ [0:a]atempo=25/24[a]" \ -map "[v]" \ -map "[a]" \ output_file
ffmpeg \ -i input_file \ -r output_fps \ -filter_complex \ "[0:v]setpts=input_fps/output_fps*PTS[v]; \ [0:a]atempo=output_fps/input_fps[a]" \ -map "[v]" \ -map "[a]" \ output_file
A complex filter is needed here, in order to handle video stream and the audio stream separately. Please note that sadly the parameter’s order for the image and for the sound are inverted.
The quotation marks allow to insert a space between the filters for readability.
As usual in the IT world, the numbering of the channels starts at