Viewing Shifted Video

I am trying to get perfect audio and video sync using the test video found here:

When I shift the audio track I have the audio waveform as a visual guide and it’s easy.

When I shift the video track I cannot see video and thus have no visual guide. Is there any way around this so I can see the shifted video?

Thank you.

Sorry I don’t understand this at all.

As a test, you can add the “Audio Waveform Visualization” filter to the clip. Then, you can step through the frames to see when the audio arrives. On my system, it looks like the audio is 4 frames late.

I’ll try the Audio Visualization filter.

Are you able to correct this 4-frame audio delay? I don’t know where this discrepancy creeps it, either in the original or YouTube or the YouTube video file downloader.

From the video posted I used the first download link provided.
2023-12-09_15-00-23

The video I downloaded does not have a qr-code.

For me, the audio starts at 00:00:01:31

There appears to be some bug within Shotcut though. I can duplicate what you created @brian in your screenshot, where there is no sound in the waveform depending on how fast/slow I scroll up/down in frames.

Duplicate example at 00:00:01:34

Not duplicated example 00:00:01:34

Repeatable at 00:00:00:34
I can’t duplicate the issue at 00:00:02:34.

Sync-Footage-V1-H264.mp4 ffmpeg probe.txt (2.7 KB)

Using the download link, I get audio on frame 31. Audio seems to lag video by one frame.

When previewing, audio is subject to the scrubbing setting. Try to enable Settings->Player->Scrub Audio and see if that makes any difference.

Also, is your Video mode automatic? If not, Shotcut’s framerate might not match the clip.

It was enabled. Disabled has the same result.
This is a Source only project.
Video Mode is HD1080p, 60fps. (Sorry for not stating that earlier)

The video is on an internal HDD (7200 rpm) and Shotcut is on an internal SSD.
Project file and settings all SSD.
I have yet to test the video file on an SSD.
Shotcut application log.txt (54.7 KB)

I do not think the drive type will make a difference.

You are probably experiencing seeking inconsistencies. I tried, but did not experience that myself. I think that seeking in mp4 files is pretty good, but not perfect. Have you tried the second link (ProRes)? When I tested it, the audio/video sync was perfect.

I get 2 frames of audio delay if the keyboard is advancing/retarding one frame per keypress.

The VU meters are very handy in spotting the audio.

A keyboard command which shifts the currently-selected track by one frame in either direction asynchronously from the associated audio/video track would be handy and steadier than the mouse.

See Properties > Audio > Sync

This is implemented for the next release.

1 Like