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TOPIC: Moving Audio along timeline

Moving Audio along timeline 7 years, 3 months ago #47823

  • deeflash
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  • 7 years, 3 months ago
Hello,

I am getting started with Lightworks and really am enjoying learning it but I have run into an issue when importing outside audio.

We recorded an event using a GoPro Camera and have a recording of the audio straight from the mixing board as a wav file. I brought the clips in from the camera and aligned them. But now when I bring in the wav file I can only move and edit it between frames. Unfortunately, cannot move it in any smaller increments, so the audio is out of sync. Is there a way to move audio by milliseconds rather than frames?

Thanks,
Chris

Re: Moving Audio along timeline 7 years, 3 months ago #47830

  • dancerchris
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No.

I have requested this as a feature already, but suggest you do the same.

Frame level only audio syncing can have an offset error with dual audio sync by as much as +/- 21 ms at 24 fps. This goes down at higher frame rates and if your Go-Pro footage is at 60 fps this drops to a sync error of only +/- 8 ms. Since sound travels approximately 1 foot in 1 ms the offset can be expressed as listening to the same thing at a distance that is the ms value in feet. Numerous studies have shown that people's perception notice a off-sync at somewhere between 10-20 ms. So if you are shooting 60 fps you should be okay at 8 ms. (equiv to 8 foot delay). There may be other factors in your syncing issues like hardware latency between monitors and the audio. This is notorious as many milliseconds response can happen and there is some adjustment that can be made to compensate for this in playback in LWs.

It is also interesting to note that audio that is heard prior to the visual event is VERY noticeable, while our minds are very accepting of the audio occurring after the visual event. This is because it always happens (light is faster than sound). So from a purist point of view the +/- values quoted above should be doubled for the sync error since we always want the audio to occur after the event. 60 fps footage moves into the barely noticeable to a trained ear and eye, but the 24 fps is definitely out of sync. This becomes particularly important with sound effects. Gunshots, explosions, slaps etc.

All that being said the users should push for subframe audio control during editing.
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Re: Moving Audio along timeline 7 years, 3 months ago #47831

  • deeflash
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Thanks for the quick response. I have been recording at 1080p 30fps because I find it works better at low light for us. I decided the also that it was better to push the audio after the action. I just would've liked to include some of the ambient sound that the camera picked up as well but it was too noticeable of a delay between the two.

Re: Moving Audio along timeline 4 months, 1 week ago #218168

  • romanos9
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  • 4 months, 1 week ago
I'm having the same issue (not being able to sync audio because I can't move it in small enough increments). I noticed that the previous conversation was 7 years ago. Have they done anything yet that allows me to fix this problem? What' the point of adding audio if you can't sync it? Should I just switch to Adobe Premiere or something? I'm new to this so sorry if it's an obvious answer.

Re: Moving Audio along timeline 4 months, 1 week ago #218169

  • briandrys
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Welcome to the forum.

For syncing audio to the picture you only need to be accurate to a single frame. As long as the sound is made within that frame you can't be more accurate.

Sub frame editing is more for phasing the audio between the audio tracks, not syncing to the picture.

Re: Moving Audio along timeline 4 months, 1 week ago #218171

  • romanos9
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Thanks for the response. So when I view the footage in edit mode, the audio sounds slightly off. In addition, the spike in the wave where the slate hits is slightly off as well when zoomed in. Are you saying that this will not be an issue when I export the video? Or are you saying that even though it's slightly off, it's "good enough"? I just don't want to put in all the work and have to redo it all. Thanks.

Re: Moving Audio along timeline 4 months, 1 week ago #218172

  • briandrys
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You can precisely sync the slate clap to frame where it visibly closes. When you zoom in, the audio waveform should be set to start in the clap frame.

Some users want to precisely line up the waveforms on the camera audio to that on an external recorder. You don't need that, you just need them both of these to be starting in the same frame.

If you've synced both up and they look out of sync, that could be something else happening.

What method are you using to sync with your slate?

Re: Moving Audio along timeline 4 months, 1 week ago #218181

  • romanos9
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  • 4 months, 1 week ago
I manually dragged the audio file over to the approximate area. I know there is a sync option that I saw in a tutorial video but I can't seem to find that video at the moment. But the clap (both audio and video) are in the same frame so hopefully that will be okay. Maybe I'll export it just to see how it comes out.

Re: Moving Audio along timeline 4 months, 1 week ago #218184

  • hugly
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  • 4 months, 1 week ago
Hello,

I understand that you have recorded a clap.

Please use the waveform to sync the audio to video at the position of the clap and then play.

Is the sound at the clap in sync and does it drift more and more out of sync the longer you play?
It's better to travel well than to arrive...

Re: Moving Audio along timeline 4 months, 1 week ago #218188

  • romanos9
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That's another issue I'm having. I had a bad audio delay. I looked up ways to fix it. I updated Realtek to whatever they suggested and my computer no longer played sound so I reverted it to the original one. But on top of that, I can't get the audio and video clap exact. I record a lot of audio on GarageBand and I can simply drag a track to match it up perfectly with another. I figured I could do that here with audio and video.

Re: Moving Audio along timeline 4 months, 1 week ago #218192

  • hugly
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Ok, thank you.

If you should see drifting sound on separately recorded audio, there are settings to correct that.

You cannot cut, trim, or move audio on a sub frame basis in Lightworks. From a practical point it isn't necessary. It's sufficient to move the spike as close to the frame as possible.

I've attached a sample video to illustrate. Import it into Lightworks and inspect the claps.
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Last Edit: 4 months, 1 week ago by hugly.

Re: Moving Audio along timeline 4 months, 1 week ago #218199

  • jwrl
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romanos9 wrote:
I can't get the audio and video clap exact.

hugly wrote:
You cannot cut, trim, or move audio on a sub frame basis in Lightworks. From a practical point it isn't necessary. It's sufficient to move the spike as close to the frame as possible.

In saying that, hugly is quite correct. When you visually identify the first frame on which the clapper is closed the only thing that you can say with any degree of certainty is that the clap actually happened some time during the previous frame. A camera doesn't gate it's frame updates to match critical action such as a clapper closing.

What this means is that if you line sound up exactly to the frame that you see the clap on the sound may already be nearly a frame late and you have no way of knowing by how much it is out. Sub-frame accuracy with sound syncing is really irrelevant, unless you have some means of precisely identifying when the clap actually happened during the previous frame. Not even timecode slates will help you, because they also only work to frame boundaries. Fortunately the human brain will still see it as being in perfect sync.

Now if someone was prepared to make a timecode slate that started a sub-frame counter after the clap you could do it. But it would still be a pointless exercise. We are used to hearing sound after what we see because of the vastly different speeds of light and sound.
Last Edit: 4 months, 1 week ago by jwrl.
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