This is if you happen to know how far off the audio is from the video
in this case 3840 milliseconds or 3.84 seconds


*ffmpeg -i "movie.mp4" -itsoffset 3.84 -i "movie.mp4" -map 1:v -map
0:a -c copy "movie-video-delayed.mp4"*Found this here:
https://superuser.com/questions/982342/in-ffmpeg-how-to-delay-only-the-audio-of-a-mp4-video-without-converting-the-au

The hard part is knowing how far out of sync the audio is from the
video, but it's a quick change of the command line to experiment.

I generally like to avoid re-encoding the video as Gibson mentioned.
Assuming you're not doing cinematography, a re-encode may give you
more options.


On Tue, Sep 19, 2023 at 9:32 PM Michael L <[email protected]> wrote:

> I do video editing as part of my job.
> Suggestion #1:  The Shotcut video editor allows you to separate the audio
> from video and add audio delay by moving the audio down the timeline from
> the video by 1 frame at a time or more.  That's a tough and potentially
> time consuming way to get it exact, but maybe you can fix it that way and
> re render / export the file.
>
> I'll search for another way with FFMPEG and let you know if I find it ..
> along with other info.
>
> On Tue, Sep 19, 2023 at 6:35 PM Curt Lundgren <[email protected]> wrote:
>
>> My brother sent me an MP4 file, about 900 MB, where the audio is at least
>> a second ahead of video.  I'd like to process the file so lip sync is
>> proper, but my search engine fu is coming up short.  ffmpeg seems like it
>> would have the capability, but I haven't found a clue in the documentation
>> or the man page.
>>
>> The video does not need to be changed in any way, but if possible, I'd
>> like to boost the audio gain by as much as 10 db.
>>
>> I'd prefer to do this on a Linux machine, something running from command
>> line would be ideal.  Does anyone have a clue how this can be accomplished?
>>
>> Thanks
>> Curt Lundgren
>>
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