Audio sync drifts while capturing VHS

[tonewheels]

Hello,
I'm trying to capture some old VHS tape. Don't want to spend any money on new equipment, the tapes aren't that important.
My setup is: VHS recorder composite and audio out into DV camcorder, DV out of camcorder into PC via firewire. Tried capturing on hard drive and SSD (not OS drives) without using the PC for anything else. OS is windows 7, CPU is core duo 3.something GHz. Ram about 3 megs available to windows 7 (32bit).

I've tried capturing with WinDV and VirtualDub, both with the same results. The problem is, the audio drifts out of sync over time.
My aim is to capture the whole of each video in one go, no capturing in segments and re-joining later. No buying new equpment (usless really cheap).

If anyone has any suggestions as to what I can try, or if I don't stand a chance, please let me know.
Thanks for any help,
Barry.

EDIT: Forgot to say, video is PAL.

[theewizard]

you are monitoring this process in real time
and the audio drifts while you are playing the vhs tape ?
is this a one step process, or a (2) step process ?
I think a one step process would have lots of problems, asking the camera to record and output at the same time

or do you mean, the audio drifts, when you play back the captured file on the PC
could this be dropped video frames, but the audio was recorded ?
if this is the case you might try reducing the video capture bitrate and possibly the capture frame rate

or you may have too, choose a different method such as dedicated capture hardware, with hardware mpeg encoding,
where the PC only has too save the info coming through the USB port,

[jagabo]

It's DV he can't change bitrate or frame rate. Try capturing type 1 DV AVI in WinDV. See if that helps.

[tonewheels]

Thanks for the replies. A bit more info to clear things up:
The camcorder has what I've seen described as "pass-through". It will take the analog input, convert it to DV and send it out through firewire.
It also plays back normal video8 and Hi8 tapes and sends the DV out through firewire. I've captured almost 50 video8 tapes this way and have no problems with audio drifting out of sync. Only a few dropped frames usually at the start of the tape where it's noisy. The only problem is when using the pass-through method with an external VHS recorder.

I'm not monitoring audio while capturing. On playback, either with VLC media player or virtualdub, the further I play into the video, the more the audio is out of sync.

I'll try DV type 1 as you suggest and report back.

Thanks a lot for your help.

[pippas]

I'm not monitoring audio while capturing.

That's the one drawback with WinDV. No audio monitoring. You might like to try using Scenalyser which does include audio monitoring.
Originally a payware program which is now (understandably) no longer developed, it is now freeware.

[tonewheels]

I tried DV type 1 with WinDV on a 2 hour tape and the sync is good throughout now, thank you. Still curous as to why that would be if anyone knows. All the video8 tapes I captured with DV type 2 were okay.
Haven't tried scenalyser yet.

[theewizard]

Glad you got a working method
I've no experience doing this, the way you are doing it
There is a difference between playing hi 8 tape directly
And using the camera as a converter from VHS to digital output

[jagabo]

I tried DV type 1 with WinDV on a 2 hour tape and the sync is good throughout now, thank you. Still curous as to why that would be if anyone knows.

When a DV camcorder sends data to the computer the audio and video are muxed together. In a type 1 DV AVI file that stream is stored in the AVI as-is, marked as a video stream. There is no separate audio stream. In a type 2 DV AVI file a copy of the audio is demuxed from the DV stream and saved as a seperate audio stream in the file. The extra work and complexity can lead to sync problems.

[tonewheels]

Thanks both. All the video8 tapes I transferred were captured in type 2 and have no sync problems.
Out of curiosity, I converted the type 1 to type 2 using DvDate and the sync problem returned. I'll capture using type-1 now that I know it works (unless it was a fluke) but with my mind, it may take me a few days before I can stop wondering what the problem is!
Thanks again.

[jagabo]

I converted the type 1 to type 2 using DvDate and the sync problem returned.

I wonder if you have some other problem. Like the player or editor isn't getting the frame rate quite right. How bad is the sync error? Does it start out in sync then slowly drift out of sync? How far is the sync off after an hour?

[pippas]

Out of curiosity, I converted the type 1 to type 2 using DvDate

I've always used THIS PROGRAM to convert between DV types, and never had any problems with either type...
It does seem as if there maybe something else causing your error though, as Jagabo has suggested

[tonewheels]

As a rough guess, audio is about 1/2 second ahead after a couple of hours. Starts off in sync and gradually drifts. Even a fraction of a second makes the video unwatchable, well, for me it does anyway.
Just tried tha canopus program, comes up with a messagebox while converting saying that the file wasn't written properly. Just creates a 5.65GB file that doesn't play. Tried on 2 DV type-1 files. Think the problem is elsewhere myself but no idea where.
Thanks for helping.

[theewizard]

do you have very many of these vhs tapes to convert
you might need some dedicated vhs to USB capture hardware to do the job
converting it thru the camcorder , does not seem to be the way to go

[tonewheels]

Resaving the DV type-1 file in virtualdub - using direct stream copy of course - saves as type-2 and plays back with good sync. As I want to trim the recording anyway, this seems to be the answer. Thanks for the help everyone.

[jagabo]

So the problem was Canopus DV File Converter?

[tonewheels]

I don't know. As well as the problem I had with the canopus converter, I also tried Ulead DV Type 1 to DV Type 2 Converter and this also crashed while converting. The only other one I tried was DVdate which converted the file okay, but the converted file exhibited the sync problem.

[jagabo]

I thought it might be the difference between 29.97 and 30000/1001 (the true value) but half a second over a 2 hour video is much more than that.

[tonewheels]

No, it's PAL.

[Brad]

All the video8 tapes I transferred were captured in type 2 and have no sync problems.

Oddly enough, I experienced this same sync drift, with Video8/Hi8. Were all your Video8 captures done using Win7?

Per this thread, switching to Type-1 did fix my problem. My thanks to all who contributed.

At the start, they're the same...


At the end, not so much...


The weird thing is, the audio tracks are actually in sync with each other...? I opened both AVIs in Audacity (FFmpeg import), aligned them near the start, and they're practically identical at the end.



(The reason for the timecode difference between the VirtualDub and Audacity screenshots is unrelated to sync. I simply trimmed 497 & 772 frames from the start of the files to match the starting frames in VDub.)

[tonewheels]

vaporeon800,
Yes, Windows 7. The video-8 captures were fine, only the VHS into the camcorder and out the firewire as DV had the problem. In the end I captured as type 1, topped and tailed it in virtualdub and saved using "direct stream copy". This saves the file as type 2 so I end with a type 2 file anyway, only in sync.