Am 28.04.2021 um 10:53 schrieb Bo Berglund:
On Wed, 28 Apr 2021 09:03:26 +0200, Michael Koch <[email protected]>
wrote:
Am 28.04.2021 um 08:51 schrieb Bo Berglund:
Sometimes when I download a video it turns out to have some issues that has
raised the audio pitch of the video making it not so enjoyable to watch/hear.
So I wonder if there is an ffmpeg command that can modify the pitch of the audio
without changing the playback speed or lipsync?
Yes, this is possible with a combination of asetrate, atempo and
aresample filters.
See chapter 3.4 in my book:
http://www.astro-electronic.de/FFmpeg_Book.pdf
Thanks for the book! It has many useful items.
But chapter 3.4 seems to deal only in modifying an audio file whereas I am
talking about an mp4 video with both audio and video content.
I had tested this (which I found by googling) before I posted:
ffmpeg -i input20.mp4 -filter:a "atempo=1.25" -vn output20.mp4
There were no errors displayed but the resulting file *ONLY* contains the audio
part, I neeed both and the audio change must not change the length or lipsync of
the file.
Sure, that's because -vn means "no video output". Just remove this
option and then your output file will contain audio and video.
I already have a script to change lipsync using ffmpeg this way (shifting audio
350 ms here):
ffmpeg -hide_banner -i input.mp4 -itsoffset -0.35 -i input.mp4 -map 1:v -map
0:a -c copy output.mp4
Is this basically what one has to do, specifying the input twice?
I am not really understanding how all the ffmpeg arguments do work...
Alternatively you could also use the adelay filter.
Michael
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