editing Lightworks Audio Sync

[RyiGarry]

While I am working in Lightworks, I often encounter the problem of how to synchronise sound (added sound like music, not embedded audio) to the video. For example, oftentimes the clip will preview perfectly in sync, and then once it's rendered will be just a few frames too early or too late.


I also have a picture of something that confuses me, that might be related:

You can see the marker is one frame behind the location of the video clip. Which should I pay attention to? For example, in the picture, it's obvious from the waveform where the start should go (where the audio increases volume from silence) - but do I put the marker there or the actual beginning of the clip?

 

[Will Vincent]

You need something (clapboard) to use to match your audio to video.. it sounds like you're just trying to guess right now, that's not gonna be a whole lot of fun.

 

[AudioPostExpert]

While I am working in Lightworks, I often encounter the problem of how to synchronise sound (added sound like music, not embedded audio) to the video. For example, oftentimes the clip will preview perfectly in sync, and then once it's rendered will be just a few frames too early or too late.

There are a number of potential causes of that problem: A mismatched frame rate somewhere (it's not uncommon to see mismatches between 24 and 23.976fps). Mixing different audio formats or converting to different formats on export might be cause in some cases or it could even be a bug in the program.

You can see the marker is one frame behind the location of the video clip. Which should I pay attention to? For example, in the picture, it's obvious from the waveform where the start should go (where the audio increases volume from silence) - but do I put the marker there or the actual beginning of the clip?

Sorry, someone with specific knowledge of Lightworks is going to have to help you with that one.

G

 

[RyiGarry]

You need something (clapboard) to use to match your audio to video.. it sounds like you're just trying to guess right now, that's not gonna be a whole lot of fun.

The problem is, even if I had a single point like that to sync to, it wouldn't necessarily be the same in the preview window as it is when it's rendered.

There are a number of potential causes of that problem: A mismatched frame rate somewhere (it's not uncommon to see mismatches between 24 and 23.976fps). Mixing different audio formats or converting to different formats on export might be cause in some cases or it could even be a bug in the program.

I've tried exporting in a number of different compression formats and containers - they all exhibit this problem. As you say, I presume somebody experienced with Lightworks should help me - it seems like this is a part of the program: from the gap between the clip and the marker.


Thanks both for your answers!

 

[AudioPostExpert]

I've tried exporting in a number of different compression formats and containers - they all exhibit this problem. As you say, I presume somebody experienced with Lightworks should help me ...

It's certainly worth consulting with someone familiar with Lightworks, although it's fairly inconceivable that such a serious and obvious problem would not have been spotted prior to release if this were a purely Lightworks issue. As I said there are a number of possible causes, another potential cause for example is hardware/driver related. The video part of your export file is rendered by one processing chain (say CPU/software driver and/or software driver/GPU and then the display), while the audio is rendered by another processing chain and the two different chains take different amounts of time to process. This is always the case! It could be that lightworks is accessing different drivers and/or hardware for it's preview than your exported file playing out of your media player, it could be that the processing of video or audio takes more or less time in lightworks depending on your editing format/s relative to your export format. Again this is pretty much always the case and would cause a discrepancy between your preview and export versions but usually this discrepancy is a frame or less (although a few frames is not inconceivable or unheard of) and not of concern to most no budget indie filmmakers. There is a solution to this always present issue but it's relatively expensive and therefore limited mainly to commercial audio post facilities.

I'm not saying this is the cause of your issue, just one of a number of possible causes. Hopefully you'll find a simple solution if it's been encountered by a number of other Lightworks users. If not though, it might be worth considering what I've mentioned here as a potential cause.

G