Quantcast CPU spike causing audio sync issues - digitalFAQ Forum
  #1  
02-11-2017, 10:55 PM
theglenlivet12 theglenlivet12 is offline
Free Member
 
Join Date: Aug 2015
Posts: 39
Thanked 0 Times in 0 Posts
So, I'm back at it again and have solved all of the issues I had been having except for the same audio sync issue. But, I have some new information. My audio and video are in sync just fine until about the 20 minutes mark where something happens and the CPU shoots up to 100% and VDub drops tens of frames. After that, the audio is about a second behind. I don't know what's causing it or if it is some sort of limitation within VDub itself, but I am trying to get it sorted out. I had tried another video that was 51 minutes long and noticed it happened twice so it's safe to say that this behavior happens about every 20 minutes.

My questions are these:
- Is there some sort of limitation that VDub has that causes it to drop frames every 20 minutes?
- Is there something I can do to hunt down what is causing the CPU to spike if that is indeed what is happening?
- Is there a way to fix the resulting avi without the need to segment it and fix the audio and then append them? (I ask this question not because I'm lazy, but because this will be much easier to fix now than to try and do this for the much longer videos I would like to convert)

Thanks!

-- merged --

Did some more testing this morning. I went back to the part of the first tape and recorded it again to verify that it is not the signal that is causing the issue. Confirmed that it captured through the part that had previously caused the audio to desync. I am running a test with a few changes now. I have disconnected the Ethernet cable and have set the CPU priority if VDub to the highest setting. If it happens again, I will notice the time and see if it matches up to the previous capture where the audio would desync.

-- merged --

Test went good except at the 36 minute mark where the audio lost sync again. Checked the task manager and found no CPU spike but rather a spike in the disk the capture was being written to. VDub dropped 20 frames and inserted 20 frames and I would think that the sync would remain intact, but for some reason it doesn't.

-- merged --

Ran another test with the same source and found that there is something happening with the hard drive that is causing my computer to essentially stop what it is doing and write to that drive. This, in turn, causes dropped frames. VDub tries to compensate by dropping and adding frames, but the audio just goes out of sync. I don't understand why VDub will not adjust this.
Reply With Quote
Someday, 12:01 PM
admin's Avatar
Ads / Sponsors
 
Join Date: ∞
Posts: 42
Thanks: ∞
Thanked 42 Times in 42 Posts
  #2  
02-13-2017, 10:17 AM
lordsmurf's Avatar
lordsmurf lordsmurf is online now
Site Staff | Video
 
Join Date: Dec 2002
Posts: 9,786
Thanked 1,667 Times in 1,448 Posts
IDE or SATA?
Are you trying to capture to the OS drive? Or dedicated drive just for capture?

- Did my advice help you? Then become a Premium Member and support this site.
- Find television shows, cartoons, DVDs and Blu-ray releases at the TVPast forums.
Reply With Quote
  #3  
02-13-2017, 10:18 AM
theglenlivet12 theglenlivet12 is offline
Free Member
 
Join Date: Aug 2015
Posts: 39
Thanked 0 Times in 0 Posts
SATA. This drive is dedicated for capture and is not the OS drive.

I guess my thoughts as these:

We know that the issue is that data is being written to the capture drive for whatever reason which causes a pause in the data capture. This causes VDub to try and compensate for lost frames by adding frames which causes a loss of audio sync.This behavior happens at least once within a 40 minute time frame but does not happen at a specific time on each attempt to capture. Each time this happens, it seems to drop about 20-30 frames.

Should I try a new drive? Is there something within VDub that I can adjust? Is there a way I can simply capture what is being shown in the preview window?
Reply With Quote
  #4  
02-13-2017, 11:09 AM
lordsmurf's Avatar
lordsmurf lordsmurf is online now
Site Staff | Video
 
Join Date: Dec 2002
Posts: 9,786
Thanked 1,667 Times in 1,448 Posts
- SATA 150 or SATA-II 300?
- What motherboard?
- What drivers?
- Did you run a full deep analysis scandisk on the drive?
- What brand drive?
- What size drive?
- Windows XP?

- Did my advice help you? Then become a Premium Member and support this site.
- Find television shows, cartoons, DVDs and Blu-ray releases at the TVPast forums.
Reply With Quote
  #5  
02-13-2017, 11:16 AM
theglenlivet12 theglenlivet12 is offline
Free Member
 
Join Date: Aug 2015
Posts: 39
Thanked 0 Times in 0 Posts
Off the top of my head since I am now at work:

SATA III
Mobo is a Gigabyte P38Q with a i7-2600k
Never ran any drivers for it so whatever Windows has found
WD Caviar Black I believe
1TB
Of course not. 8.1.

Last edited by theglenlivet12; 02-13-2017 at 11:47 AM.
Reply With Quote
  #6  
02-13-2017, 03:07 PM
dpalomaki dpalomaki is offline
Free Member
 
Join Date: Feb 2014
Location: VA
Posts: 1,041
Thanked 226 Times in 194 Posts
Running AV on the drive?
Write caching enabled?
Reply With Quote
  #7  
02-13-2017, 03:10 PM
alexstorm alexstorm is offline
Free Member
 
Join Date: Dec 2016
Location: Los Angeles area
Posts: 7
Thanked 0 Times in 0 Posts
This seems really obvious to me that you need separate drives for audio and video files. I would never run a project with both files on the same drive. Maybe you have already done this. If not, I would guess that is your problem.
Reply With Quote
  #8  
02-13-2017, 03:22 PM
theglenlivet12 theglenlivet12 is offline
Free Member
 
Join Date: Aug 2015
Posts: 39
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by dpalomaki View Post
Running AV on the drive?
Write caching enabled?
Both no.

I am using an SSD to run my OS and have two drives that are for storage. Because I'm super committed to beating this once and for all, I went out and bought a brand new drive and am seeing just on the off chance the drive I was using was just old and starting to take a dump. I'll keep everyone posted.
Reply With Quote
  #9  
02-13-2017, 03:47 PM
alexstorm alexstorm is offline
Free Member
 
Join Date: Dec 2016
Location: Los Angeles area
Posts: 7
Thanked 0 Times in 0 Posts
Also Mobo with onboard audio is sort of a waste of time. A lot of the audio traffic is pushed to the CPU. Separate audio cards of good quality are not expensive. I use HT Omega Striker because it has separate line in and mic in. This card works fine on latest Windows 10 so probably should be fine on older Win OS.
Reply With Quote
  #10  
02-13-2017, 05:24 PM
theglenlivet12 theglenlivet12 is offline
Free Member
 
Join Date: Aug 2015
Posts: 39
Thanked 0 Times in 0 Posts
I'm quite astonished. I swapped out my capture hard drive for a brand new drive and disconnected the other drive as well so I am left with the new drive and the OS drive and the issue has disappeared. The drive I was using is about 5 or more years old and could possibly have just been too old to keep up anymore.
Reply With Quote
  #11  
02-13-2017, 06:49 PM
alexstorm alexstorm is offline
Free Member
 
Join Date: Dec 2016
Location: Los Angeles area
Posts: 7
Thanked 0 Times in 0 Posts
I still think separate audio and video drives would be best. I think every post-production for TV and feature that I worked on had separate drive arrays and separate cards driving them.
Reply With Quote
  #12  
02-13-2017, 08:43 PM
theglenlivet12 theglenlivet12 is offline
Free Member
 
Join Date: Aug 2015
Posts: 39
Thanked 0 Times in 0 Posts
I have a separate audio card, I'm just running audio through the capture card.

-- merged --

Well, I've been capturing a vhs from 1983 and am only seeing 4 frames dropped over a two and a half hour period. Not too shabby.
Reply With Quote
  #13  
02-13-2017, 11:34 PM
lordsmurf's Avatar
lordsmurf lordsmurf is online now
Site Staff | Video
 
Join Date: Dec 2002
Posts: 9,786
Thanked 1,667 Times in 1,448 Posts
I merged a lot of posts just now. Remember you can edit your last post for up to an hour.

Windows finding or not finding drivers doesn't solve the issue. However, it's usually older AMD/compatible motherboards with drivers issues, not Intel based. So moving on.

SATA III and 1tb? I didn't realize they even made newer drives that small. Are you sure it's not SATA II?

WD drives do tend to develop bad sectors more often than others. Check it.

Nothing wrong with Windows 8.1, not sure what "of course not" is for. It's a great OS for video work -- just not online work. And since you're using 8, perhaps it's also online? And background tasks are usually the culprit for dropped frames and/or audio sync errors.

Remember to read this: http://www.digitalfaq.com/guides/vid...ped-frames.htm

^ Note: Some of that no longer applies to SATA or multi-core systems, and I'm updating it to reflect that in coming months. Most of it is still applicable.

You can capture to the OS drive without any major issues, but only if a large SATA II/III with dual-core or better specs. Preferable 7200rpm. Intel or AMD. The trick is that it cannot run extraneous stuff, not be on a network, and it not be filled up. The speed and room available on it prevents clashing with the OS. Everything must be at peak operation. But, of course, separate drives are still suggested.

I've seen capturing not liking SSDs.

Onboard audio is usually not suggested, but the Realtek chipsets can sometimes behave and perform nicely. It's the one exception to the 'never use onboard audio' rule. Whatever card you decide to use, it must be tested for distortion, as some have a really awful sound quality.

Audio and video is rarely captured separately. I don't understand where that's coming from. The hardware is often separate, but the capture muxes it immediately.

4 frames over 2+ hours is fine. A bad cut scene or commercial break can cause that. And 2-3 probably happen together. So you probably dropped a few frames twice. But note that your workflow does indeed lose audio sync due to dropped frames. So the video is 2 frames off now. Not noticeable, but you don't want it to skew any more. Some workflows simply drop audio with video, so skew never happens.

- Did my advice help you? Then become a Premium Member and support this site.
- Find television shows, cartoons, DVDs and Blu-ray releases at the TVPast forums.
Reply With Quote
Reply




Similar Threads
Thread Thread Starter Forum Replies Last Post
Digital8 TRV480 vs GV-D800 audio sync issues nesburf Capture, Record, Transfer 0 11-16-2016 09:05 AM
Video glitch causing playback issues manthing Edit Video, Audio 3 11-13-2014 02:08 PM
VirtualDub audio sync issues? rds11 Capture, Record, Transfer 2 09-20-2014 01:48 PM
How do I fix out of sync audio? Superstar Edit Video, Audio 12 09-28-2013 01:41 PM
Best way to fix out-of-sync audio? Superstar Edit Video, Audio 14 07-24-2013 01:38 PM

Thread Tools



 
All times are GMT -5. The time now is 12:41 PM