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Audio Sync issue in rendered videos

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Topic starter

When using an audio from a separate audio recorder source (i.e. not from the video file), the sync is correct in the timeline, however when I render the video the audio is about 3 frames too late. I am experiencing major issues at the moment, when trying to sync audio with video from a 2 camera setup.

I can align the audio from the three sources in the timeline, and they all play correctly in sync with each other. However, when I render the video using only audio the external recorder, the audio is about 3 frames late. Each time there is an edit in the external audio, then the sync drifts a further 3 frames or so out.

Any suggestions?


2 Answers

How do you see the audio is about 3 frames late?

glitterball3 Topic starter 30/09/2021 1:41 pm

@igorbeg That's a rough estimate: if I move the audio back 3 frames (so that it plays back ahead of the video in the timeline), then the audio is roughly in-sync in the rendered video.


Okay @glitterball3 I try to start from zero,... and excuse me if always you know that.
Check two things:
1. Menu-> Settings-> Preferences...-> Playback_A (TAB).
In "Video Out" section check that "Play every frame" is unchecked.
2. On the left side of the Program window (Timeline) there is the Patchbay: check that TextBoxes for the Audio tracks are all to zero (0.0000), please.

May be it doesn't matter but,
to align audio with video, are you using a "ciak/clap" way (manual mode) or Multi-cam with audio sync (the easy way)?

Finally, take a look at the post "Odd trimming behaviour" in the Forum to understand if your 3 frames gap is the same behaviour, please.

glitterball3 Topic starter 03/10/2021 1:41 pm
This post was modified 3 years ago by glitterball3

@igorbeg Unfortunately none of that is relevant.

To clarify: I can consistently reproduce the sync issue; it happens every time I import audio that is not part of a video file.

What I am doing: Often I will export the audio and bring it into a DAW for further processing (compression, lookahead limiting, eq, high pass filter etc.). I was an audio engineer for many years, and I just find the metering, bussing etc. much easier to work with a proper DAW.

When I export this audio from the DAW, and import it back into Cinelerra, it lines up correctly - both visibly in the waveform, and audibly.
When I then render the video, the audio is always out-of-sync.
If I render the video with the original audio from camera video file, there is no sync issue.

I will do some more tests with file formats and bit depths, to see if I can find any obvious bugs.


Update: It seems it's a little more difficult to reproduce than I thought: The last four videos that I've completed have all had this issue (they are all interviews with the same 2 camera setup), so I have started rendering a test video after every change I make during the editing of this format of video (after each effect addition etc.).. So far, I have rendered about 10 tests, and the sync is still okay...

IgorBeg 04/10/2021 9:57 am

It is more clear, now. Thanks, @gitterball3.

I guess you tried rendering with different output containers (h264, mov, mt2s) and setup.

JAMES77 29/10/2021 1:45 pm

Thanks for this information @gitterball3.

Now I have no sync issue. I export and render video also in Movavi video editor - URL. There are no problems at all.