Audio Video Sync issues v20.02.17

I’m running low on ideas, but one other comes to mind… How are you viewing the exported video? Using VLC? If so, what happens if you export the project without offsets using the YouTube preset and view it with any media player besides VLC? Or what if you bring a ProRes export into the Shotcut preview window and play it back there? I have experienced VLC lose audio sync on perfectly good files because of playback problems specific to that program, so there could be a chance your exports are fine if viewed in another player.

There are several great options. The setup I personally use is a Panasonic G85 ($700) which gets you fantastic 4K with unlimited record time. (Most DSLR/mirrorless options are capped at 30 minutes.) Pair it with a Beachtek DXA-Micro-Pro audio adapter ($140) which accepts two 3.5mm plugs (from wireless mic receivers or a hot shoe mic) or one XLR mic. It outputs a 3.5mm signal that can plug into any camera’s 3.5mm mic input port. This would leave a lot of money left over for lenses, since it looks like your video is indoors where it’s dark and a fast prime lens may be needed for good video quality. There are other audio adapters similar to the Beachtek if you need two or more XLR inputs, like the Zoom F6 ($650).

Those durations refer to the base media file, not the individual clips snipped from it.

@Camzl1 Any chance you have an external sound card or audio interface?

Solution: Go by your Markers and wave form alignments and not preview to sync audio.

You guys aren’t going to believe this. Dan nailed it. I am using the preview to sync my audio to video even though I have markers in the audio file and which collates with the cameras audio. The part you aren’t going to believe is that it takes exactly 6 frames advancement of my audio to line up the markers and waveform. There must be some similarity somewhere in the first post I pointed to though. I wasn’t looking at the wave-forms as I thought preview sync would collate into the real thing. How that is consistent between each project squarely lands on the hardware as Dan has stated. So I determined this by aligning the markers and wave forms on each project. This puts the preview audio out sync. Then I measured the space I moved on each project and there it was 6 frames on every one, but, again the wave forms align up. So it’s a preview problem, but now it’s been explained and I will continue on. I will test this on my new projects coming up and keep you posted. Thanks Dan. Thanks Austin for the tips below.

Again if there is a setting in Shotcut that I need to use that you may recommend, that may in the future possibly allow the preview audio to sync up as I align to the waveform, then just point me in the right direction. I believe as Dan has stated and it is system dependent. The same thing was happening in kdenlive and is why i jumped ship. I like Shotcut better but now it all makes sense.

I will mark this as Solved as Solution

Thanks for the follow-up! Very interesting.

Thank you for the feedback.
Yes, audio cards/interfaces add extra latency which varies from card to card.

In final mix we use the Pro Fire 610 and Pro Tools, however Pro Tools has a setting to compensate for this.

Any chance of getting something similar in SC?
Perhaps in the set-up menu, an option to allow the user to add or subtract an offset in milliseconds to compensate?

Yes, I am thinking about how to do it. Typically, I am using audio output though HDMI or whatever is built into my MacBooks.

Thank you for looking at the AV sync issue, it will be really great to have this.


I have been having similar issues and am feeling slightly out of my depth (novice in terms of video editing tbh). I see you talking about markers. How do I insert markers? I haven’t been able to find anything on the forums about how to do it.

Thank you in advance!

I added something here (Settings > (Player) Synchronization…) to add/adjust a video delay for the next version 20.06. You can adjust it while something is playing - preferably something known good. We also have in Open Other something called “Blip Flash,” which is a synthesized a/v sync test pattern. You might also find an improved synchronization in preview by default in the next version since I had to tweak the timing system in the process.

Markers are what we refer to as a reference point in the audio such as a loud clap followed by silence. You can do these as often as you want but, the more you do the more you have to split, and then remove them when editing. Same thing in video shooting with the marker boards and why they had that swing arm to smack and create that “Pop” sound so you get a spike on the wave form to visualize your reference point. They are called clapper boards, but I hate that term and call them mark in boards.

Can you explain this further? Because I don’t understand syncing to “something known good”. I’m understanding “known good” as it being synced so if something is already playing in sync why would it need adjusted?

Are there any instructions on how to use “Blip Flash” in Shotcut in order to fix a/v sync issues?

This thread is about a/v synchronization of the playback system because audio and video typically take separate routes out through the computer system (unlike a Blackmagic Design SDI/HDMI peripheral). You even reported about this before. This is not about correcting sync problems in a media asset; that is already in Properties. “Known good” means using a media source with audio and video that are trusted to be in synchronization. That could be a specific test sequence or perhaps something with good talking head dialog. I would include in “trusted” something that does not use temporal compression or suffer codec delay.

Are there any instructions on how to use “Blip Flash” in Shotcut in order to fix a/v sync issues?

No, they are not even released! But basically, Open Other > Blip Flash > OK. Then, watch and listen. Next, if needed, choose Settings > Synchronization… and adjust using the slider or spinbox to make the blip and the flash best coincide.

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You misunderstood me. :slightly_smiling_face: I know what the thread is about because as you said I had reported on it before. But the a/v sync issues that I have experienced don’t happen with every file. It only happens on some files and those are not sync issues that are inherent in the file because they are not out of sync played outside of Shotcut.

So when I asked about “something known good” that’s what I meant: A file that is having a/v sync issues only in Shotcut not files that have inherent sync issues.

No fixes for that. You can use properties sync to compensate for that.

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