[Cin] Audio out of sync when rendering MP4s

[Phyllis Smith]

Not sure if this will help or not, but the default Settings is "Align
cursor to frames" as seen in the Settings pulldown.  But you might try to
"Align cursor on frames when editing a video track and Align to samples
when editing audio".  Check the box on for video and off for audio in the
Settings pulldown.

On Wed, Jan 31, 2024 at 3:30 AM Matteo Bini via Cin <
cin at lists.cinelerra-gg.org> wrote:

> Hello Cinelerra GG developers,
> I've found a strange behaviour in this great editing software.
>
> When I render my project, sometimes the audio is out of sync. Not all
> the audio, but from a certain point, from half of the video the audio is
> out of sync and it gets worst the more we get to the end of the video.
> It's like latency piles up. I've only done MP4 renderings so far.
>
> My idea, but I don't know how to demonstrate it, is that ffmpeg doesn't
> know how to render audio and video in sync, when there's some audio that
> is not aligned on frames. Since I do a lot of precise audio editing in
> my project, there are some audio cuts that are not aligned on frames.
>
> It's not a big problem, I just wanted to let you know. The solution is
> very simple: render only the video track, then render the audio track in
> WAV and then mux them together with ffmpeg, copying the video track and
> encoding the audio one. This way the video is perfectly in sync with the
> audio.
>
> The strange thing is that, when I watch my project from the compositor
> window, audio and video are in sync.
>
> Thank you for making Cinelerra GG a really great free software.
>
> --
> Matteo Bini
> --
> Cin mailing list
> Cin at lists.cinelerra-gg.org
> https://lists.cinelerra-gg.org/mailman/listinfo/cin
>
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