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TOPIC: Audio lag

Audio lag 1 week, 3 days ago #218696

  • Viminalis
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  • 1 week, 3 days ago
Newbie here; I've never edited even audio before. Thanks for this wonderful resource.

The purpose is to create some didactic videos about music from home. There is a speaker and short musical clips are interspersed. These are taken from YouTube, mostly, respecting legal rights as far as we know. We haven't yet used our own CDs; we have recorded bits from our DVDs with Windows+G... but that's another story. We've managed to assemble two programmes, recording the explanations with an iPhone and diving right into LightWorks with abandon.

For the third programme, the speaker has recorded himself on Windows Recorder. The videos look alright when played on VLC. But when we import them to LightWorks, some (not all) of these recordings show a very noticeable and variable lag between video and audio.

I've checked some of the posts here trying to find a solution. Some of the methods I've used might be magical thinking, but... I've moved the source videos to the hard disk. I've downloaded HandBrake and converted the videos to the same frame rate, so as to use Auto instead of Mixed Rates (as in the first two programmes). I've added videos and audios separately to the timeline using the alt+v shortcut. (I've since tweaked the Realtek drivers, following instructions given here, but after recording, so the clips are the same.)

One of several strange things (for me, obvs): yesterday, LightWorks couldn't reproduce properly the first two programmes; the lag was awful. It has disappeared today.

The problem is that the lag is unreliable. We adjust video and sound carefully in our project and then, after exporting, there is a somewhat different lag, but a very noticeable one.

I'm attaching the MediaInfo of one of the offending videos. Thank you all.
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Lightworks 2020.1; Windows 10, 64 Bit
Laptop AMD Ryzen 5 3500U with Radeon
Vega Mobile Gfx 2.10 GHz
RAM 8,00 GB (5,95 GB usable)

Re: Audio lag 1 week, 3 days ago #218697

  • hugly
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  • 1 week, 3 days ago
Hello,

Could you post your computer details (Lightworks and OS version, CPU, RAM, GPU, HDDs) please?

What is the typical audio latency in Lightworks preview on your system in tenths of seconds with HD material in AVC/AAC.MP4 format, aprroximately?
It's better to travel well than to arrive...

Re: Audio lag 1 week, 2 days ago #218725

  • Viminalis
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  • 1 week, 2 days ago
Thank you for your interest.

Lightworks 2020.1, free version; Windows 10, 64 Bit
AMD Ryzen 5 3500U with Radeon Vega Mobile Gfx 2.10 GHz
AMD Radeon Vega 8 Graphics
RAM 8,00 GB (5,95 GB) 2400 MHz SODIMM
Toshiba MQ04ABF100, 932 GB; SK hynix BC501 HFM256GDJTNG-8310A, 239 GB

I'm not sure I can answer your questions properly, I'm sorry! (What counts as HD...?) I've added the MP4 video whose MediaInfo I attached, one of those recorded with Windows Recorder, to the timeline and adjusted audio and video. The audio should start at approximately 0.24 seconds into the video. (I've repeated the adjustment with another of those videos recorded with Windows Recorded and it shows a similar lag.)

Then I've exported that video as mp4. Video lags behind audio; I cannot say how much, but I think less than 0.24.

Sorry to be so imprecise. I have been eyeing the computer with distrust for several days now, and I don't really know what matters and what doesn't, but I'd like to add that a suspicious crack can be heard occasionally. I'm not sure that the speakers or the microphone behave as they should here.

On the other hand, I'd repeat those recordings made with Windows Recorder with my iPhone and be done with it; even if it takes a long time, this is taking more (and your time, too!). What stops me a little is the fact that Lightworks garbled audio and video of those two programmes filmed with iPhone too – only for some hours, but it did garble them. And, well, I'd like to know if I can use Windows Recorder. The speaker reads his scripts; this is less noticeable with the built-in camera and looks better.

Thank you again for your kindness.
Lightworks 2020.1; Windows 10, 64 Bit
Laptop AMD Ryzen 5 3500U with Radeon
Vega Mobile Gfx 2.10 GHz
RAM 8,00 GB (5,95 GB usable)

Re: Audio lag 1 week, 2 days ago #218726

  • Viminalis
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  • 1 week, 2 days ago
Rechecked my 0.24 seconds number. I'd correct it to 0.3. (I can't edit a post, can I?)
Lightworks 2020.1; Windows 10, 64 Bit
Laptop AMD Ryzen 5 3500U with Radeon
Vega Mobile Gfx 2.10 GHz
RAM 8,00 GB (5,95 GB usable)

Re: Audio lag 1 week, 2 days ago #218727

  • hugly
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  • 1 week, 2 days ago
Hover with the mouse over the '< MENU' button and you'll see the 'EDIT' button.

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The term 'HD' is commonly used for a resolution of 1920x1080 pixels.

0.3 seconds are appr. 10 frames at 30 fps. What do you think, is it possible to sync sound to picture by listening in preview with such a delay with acceptable results?
It's better to travel well than to arrive...

Re: Audio lag 1 week, 2 days ago #218730

  • Viminalis
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  • 1 week, 2 days ago
The term 'HD' is commonly used for a resolution of 1920x1080 pixels.

I see. The videos recorded with Windows Recorder are 720p.
0.3 seconds are appr. 10 frames at 30 fps.

Yes - exactly 12 frames.
What do you think, is it possible to sync sound to picture by listening in preview with such a delay with acceptable results?

Again, not sure I understand, sorry. I've just added the video to the timeline with lag and all, exported as mp4 and the lag is still there. Whether I correct the lag or not in the timeline doesn't make much difference; the results are unreliable. A bit better maybe with my correction, but not much.

Thanks again for your interest.
Lightworks 2020.1; Windows 10, 64 Bit
Laptop AMD Ryzen 5 3500U with Radeon
Vega Mobile Gfx 2.10 GHz
RAM 8,00 GB (5,95 GB usable)
Last Edit: 1 week, 2 days ago by Viminalis.

Re: Audio lag 1 week, 2 days ago #218732

  • hugly
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  • 1 week, 2 days ago
I answer to my question is: It's impossible to sync by listening with such a delay, you shouldn't even try it. The only chance is syncing by watching the waveform, if there are suitable spikes.

I've attached a video, import it in a 24 fps project, the claps will appear delayed in preview, please don't try to correct the sync relation, export and play it with a media player. I suspect it's in sync. Is it?
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