How to precisely determine the delay (in ms) when muxing video and audio

[vangeliis]

Hello,

I am trying to correct an out-of-sync movie by applying a delay in milliseconds to the audio track in mkvtoolnix. So far I have used VLC's track synchronisation to manually determine the delay. However this method is not very precise as shifting the delay by 50-150ms does not make any difference -at least in my eyes.

Is there a way to precisely and automatically determine the delay and then give it to mkvmerge when mixing?

Many thanks,
vangeliis

[johns0]

I use mpc-hc to calculate out of sync shows,works great and with good precision.It does graduations in milliseconds.

[manono]

Precisely? Like to the millisecond? No. Automatically? Not a chance. However, VLC isn't accurate enough. In MPC-HC you can adjust in 10ms increments. But if 50ms and 150ms don't sound any different to you then there's no way you'll be able to tell just by listening. When I want more accuracy I use AviSynth's AudioGraph filter to impose a waveform over a video to tell when a sharp noise, like a gunshot or something similar, takes place. It can come to probably 20ms or so of being accurate, given that the video frames are roughly 40ms apart. And it's usually said most people can't tell the difference up to about 100ms.

[vangeliis]

I use mpc-hc to calculate out of sync shows,works great and with good precision.It does graduations in milliseconds.

Thanks for the pointer. I should have mentioned I use a mac.

Is there another way than lip-reading?

[vangeliis]

Precisely? Like to the millisecond? No. Automatically? Not a chance. However, VLC isn't accurate enough. In MPC-HC you can adjust in 10ms increments. But if 50ms and 150ms don't sound any different to you then there's no way you'll be able to tell just by listening. When I want more accuracy I use AviSynth's AudioGraph filter to impose a waveform over a video to tell when a sharp noise, like a gunshot or something similar, takes place. It can come to probably 20ms or so of being accurate, given that the video frames are roughly 40ms apart. And it's usually said most people can't tell the difference up to about 100ms.

Using waveforms sounds already much better. Is there anything for the mac? Other than iMovie?

what about timestamps?

[manono]

Lip reading is no good at all. As I said, a gunshot. A door slamming. Any kind of loud sharp noise.

I know nothing about Macs. Sorry.

[johns0]

Thread moved to the mac forum where you can get more help.

[JVRaines]

Lip reading is no good at all. As I said, a gunshot. A door slamming. Any kind of loud sharp noise.

Dialogue can be synced with practice, but a sharp, loud sound with visual cue is best. That's why they still use these for backup.

For a free video editor with waveforms, check out https://www.openshot.org/.