Avidemux Forum

Good afternoon to all of you,

I tried Avidemux on the fly (for the first time) and I managed to speed up the audio track. I couldn't do it for the video track, so much so that the audio ends before the video. Is there a way to speed up both the audio and the video in a synchronized way? Thanks.

I don't know if you also find this but Avidemux is one of the few programs that can speed up an audio track (Time-Stretching) without it undergoing annoying flanger and/or Chorus effects. Up to now the best program that speeds up a project without ruining the audio too much is Movavi Video Editor (which however lacks the H265 codec). Then Avidemux - Olive Video Editor - And Magix Video Deluxe (which however is always heavy and a bit cumbersome...). I tend to make video tutorials with my voice, but to try to be as clear as possible (in speaking) I have to speak slowly and this means making long videos with a boring voice... The function to speed up the project is vital for me but I can assure you that, of the most bombastic video editing programs, only those mentioned above by me (and perhaps others that I have not tried) are able to speed up the audio track without ruining the speech too much. The rest of the programs tend to create a strange flanger (or chorus) effect that I can't explain to myself (and no one has ever been able to explain to me...). Perhaps, before reducing the video time, you need to convert the audio track to mono, but again, there aren't many programs that can do that.

Use "Change FPS" video filter (eventually followed in the filter chain by "Resample FPS" to bring the actual FPS down to the original value) to speed up the video track. If the video is sufficiently long, some loss of sync at the end may still happen due to limited precision.

(edit: Obviously, video filters are not applicable and therefore not available in copy mode, select a video encoder first to access the filter manager.)

Quote from: eumagga0x2a on April 18, 2025, 12:33:39 PMUse "Change FPS" video filter (eventually followed in the filter chain by "Resample FPS" to bring the actual FPS down to the original value) to speed up the video track. If the video is sufficiently long, some loss of sync at the end may still happen due to limited precision.

(edit: Obviously, video filters are not applicable and therefore not available in copy mode, select a video encoder first to access the filter manager.)

Thanks anyway but this way it becomes difficult... I hope you can implement, in the future, this function in your future updates and upgrades... I will try to search for more... Thanks for the help. Regards.

To achieve the best results, you have to first apply the "Change FPS" filter.
Then, in the Audio filters, selecting the "Custom" Frame rate change, the default value will be optimal.
 

Quote from: Boflox on April 18, 2025, 12:27:16 PMThe function to speed up the project is vital for me

Try FFMpeg:
ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=0.8*PTS[v];[0:a]atempo=1.25[a]" -map "[v]" -map "[a]" output.mp4- this speeds up the video "input.mp4"  by 25%.