Audio Sync Issues

[whiplash]

I just went through my first excercise of captuting A/V from my analog camera to my PC and then to DVD. When I looked at the finished product it had audio sync problems. This is also happening in the original captured video.

I am doing this as a somewhat test, using the video capture capabilities of my Asus video card and the motherboard audio functions. I know this isn't the best solution and I am trying to decide what to get to capture the A/V properly. My PC performance shouldn't be a problem. I have a dedicated AMD 1400/512Meg RAM machine with WD ATA100/7200rpm drives. When capturing 2 hours of A/V, I had 40 dropped frames.

I am trying to decide between getting a Canopus ADCV-100 or getting a new video camera that supports analog passthrough.

I would assume from reading the Canopus site that there shouldn't be any audio sync problems. But it does seem like a lot of money for the function it is performing.

I was also thinking that instead of geting the capture hardware to put the money towards a new video camera that supported A/V passthrough. I am curious if this should take care of the audio sync issues or if it may still be a problem when I try to capture the analog A/V. It probably has a lot to do with the camera. I have always liked Canon and I'm looking at the Elura 40MC.

Any comments would be appreciated.

[Bizuser]

You need to tell us how you are capturing. Using what program? Eg- using VDub (Virutal Dub) to AVI? Or using some program that goes direct to MPEG2 (MPEG2 on the fly)?

Is the synch problem there at the start; or does it gradually become noticeable?

I'm having the same kind of issues - few dropped frames, but slight audio synch problems, using VDub (and others) to AVI. My synch problems are not gradual drift, but rather simple 'lack of synch' - very slight indeed, but yet noticable during speech.

If I capture direct to MPEG2, I get gradual synch drift, but only after demux/remux of the file (which is necessary for me before I can author to SVCD).

So there are many different types of problem. Let us know what your problem is.

I'm thinking that the solution is going to be a dedicated card that has both audio and video capture functions built in, where (presumably) the two can be clearly synched up (the root cause of these issues seem to be the fact that the audio capture is done by the audio card, which is off in it's own world relative to the video capture). Either that, or an MPEG2 capture card that does a great, fully compliant job, such that when you either cut/paste, or even demux/remux the streams, they don't fall apart synch-wise.

I'd certainly prefer to capture direct to MPEG 2 if possible. My AIW 128 does a great job of capturing to MPEG2 - the resulting file plays great on my PC and has no synch problems - but it's non-compliant so when I try to burn to SVCD, it won't. When I manipulate it (demux/remux) to get it to burn to SVCD, the synch goes to hell.

Good Luck!

[whiplash]

Sorry I was trying to make a short post, and left out some of the detail.

I captured the video using Video Explosion which uses the Nvidia WDM Capture Drivers provided with the video card (Asus V9180 Video Suite, Nice card). I captured it to a .avi file that I could then edit with Video Explosion and then render into a .mpeg for burning onto a DVD. I'm not sure when the audio sync is lost in the .avi file, but at 20 minutes it isn't noticable, after an hour you can tell there is a problem and at 1:40 it is pretty bad. There are several frame losses scattered through out the capture, with a total of about 40.

I think you are right on the root cause being that the audio and video processing is being done by 2 different hardware/software processing. I'm not sure if the frame drops of the video is causing the out of sync, but it is probably safe to say it is. I knew it could be a problem going in and was hoping it would work, but was expecting that I would have to get a analog capture card. I guess I could capture the .avi in smaller chunks, but the under lying problem is still there, it just wouldn't be as noticable.

Recently I saw that some video cameras have the analog pass through functions. I was hoping the camera could lock the analog audio and video before sending it to the PC across the firewire interface. This would allow me to transfer my existing analog tapes to DVD and then going forward I wouldn't have worry about analog to digital conversion any more. Of course if the camera would lose A/V sync when doing the analog passthrough, I would rather get the Canopus ADVC-100 and get a new video camera in a few years.

I have seen a couple of post of people using the analog passthrough of some video cameras. I would be curious to know if they are seeing audio sync problems when they are capturing long captures to .avi or other formats.

Mark

[DieselsDen]

I also had audio sync issues using the DV pass-thru on my two Sony cameras. I finally bought the CANOPUS 100 and everything has been smooth sailing ever since. $300 isn't cheap for this product, but it is worth all the time and frustration you spend on the audio problems.

[gadgetguy]

I have a Sony camcorder that allows the DV passthrough. I capture using ULead and it has eliminated all of the audio synch problems that I've had in the past with my ATI AIW 128 pro.

[ARL]

Gadegetguy,
What Ulead product do you use to do analog pasthrough captures with a Sony DV camcorder. I have yet to find software that will do it. I've tried DVD Movie factory and Video Studio
Tony

[gadgetguy]

I use the Ulead VideoStudio 5 DVD that came with my firewire card.

[ARL]

I have the same software, same version. I get the same problem as Iget with any other software I've tried, as soon as I hit the capture button it starts playing and capturing the tape in the minDV camcorder and ignores the feed from the Hi8 analog camcorder. If I take the tape out of the miniDV it complains that there's no tape.

[Rondo]

ARL,

I am using a Sony Digital 8 via Firewire to Videostudio 6 & I have no problems at all in the capture phase (rendering is another matter as other VS users are aware ) from VCR or direct from TV as long as I don't have a tape in the camcorder - VS doesn't complain at all. I can also capture from DV tape OK.

I wonder whether your set-up using a HI8 camcorder to DV camcorder to Firewire is the problem.

Have you verified that your DV/Firewire set-up is ok by recording something off the TV?

If that's OK then it's how you're adding in the Hi8 that's the issue.

Hope this helps!
Chris

[ARL]

Thanks guys, it was the tape in the mindv camcorder issue that solved it. I had been trying this with various programs and it wouldn't work with Microsot Movie Maker whether there was a tape in the MinDV camcorder or not. I guess I hadn't actually tried removing the tape when using Video Studio 5.