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  #1  
03-17-2019, 06:42 PM
ridzoman ridzoman is offline
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Hey all,

I am hoping someone can offer some good advice here. I am attempting to capture old S-VHS tapes and can't get past the audio drift - audio in sync in the beginning but out of sync at the end, and completed audio and video tracks different lengths.

Here's my setup -
  • VirtualDub on Windows 7 via Parallels on my 2017 iMac 4.2 Quad Core i7 with 40gb ddr4 ram w/ssd drives.
  • Elgato USB capture device
  • JVC SR-MV40 pro s-vhs deck
  • s-video and composite audio out to Panasonic DMR-ES15 and then to capture device.
  • capturing to uncompressed .avi with uncompressed audio pcm. I've tried both Huffy UV and Lagarith codecs.

Captures look good, no dropped frames. Followed Sanlyn's setup to a "t", and when drift occured I played around with Capture Timing settings and tried different options to no avail. I would like to capture with audio and video in sync. If not, if I could at least get audio and video tracks to match length, I could simply import into Premiere Pro and sync them up manually. I'm at my wits end with this project. Any advice?

Thanks,
Ridzoman
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  #2  
03-18-2019, 09:01 AM
keaton keaton is offline
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Very frustrating, I'm sure. Not sure I can be of much assistance. However, I would say that I have captured with a USB capture device (not Elgato, but a ATI 600 USB family device), and I passed my audio directly from VCR out to PC capture (not the USB, but the onboard audio or audio card line in with a mini plug for PC side to RCA audio cable for VCR side). For me, only the video would pass through the Panasonic (ES10 Line 1 In). At least for me, I haven't had any audio sync/drift issues with long captures. Cannot say if the Elgato brand has anything to do with it, and not sure how easy ATI 600 USB (or knock offs with same chip inside) are to come by these days.

Best of luck!
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  #3  
03-18-2019, 02:15 PM
latreche34 latreche34 is offline
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Give AmaRecTV a try, A lot of people moved to AmaRecTV because of the audio sync problems of Vdub.
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  #4  
03-18-2019, 05:50 PM
ELinder ELinder is offline
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I would suggest creating a Windows Bootcamp installation, not using a Windows virtual machine. I was originally going to go that route via Fusion on my iMacPro, and everyone warned me off using a VM for capturing.

Erich
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  #5  
03-18-2019, 06:14 PM
ridzoman ridzoman is offline
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What were your settings in VirtualDub? Thanks
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  #6  
03-18-2019, 06:16 PM
ridzoman ridzoman is offline
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Erich,

I was going to use bootcamp, but it doesn't support any Windows version earlier than Windows 10 anymore. I've been told I should use Win 7 or earlier for VirtualDub captures.
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  #7  
03-18-2019, 06:19 PM
ELinder ELinder is offline
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Was that directed at me? I'm saying I don't think your problem is Virtualdub, your problem is because you're runnng it in a virtualized Windows machine. Once I had Windows 10 installed and running natively with Bootcamp the capture guide you used worked for me. Yes, Win 7 is preferred, but Win 10 also works.

Erich
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  #8  
03-19-2019, 09:14 AM
keaton keaton is offline
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If you were asking me, I follow the Virtualdub Capture Guide thread written by sanlyn. I use native Win XP.

I'm not an expert, but just some general theory/hypothesizing about what could cause drift...

Since electricity travels at or near the speed of light, that's about 3 nanoseconds per meter of wire. I'm guessing humans can only detect audio mismatches on the order of milliseconds (1 millisecond = 1 million nanoseconds) So I don't think it's wiring that could cause enough drift. Perhaps there could be an offset between when video and audio capture starts if those two paths don't start at the same time. But they would remain at a constant rate of separation. My opinion is that drift would occur due to computer processing not keeping up with real-time of video and audio. When processing gets involved, there's buffering of digitized data, and things can degrade from there. It could be processing in the capture device after digitizing. It could be the capture program. Virtualization of an operating system interfacing with real-time hardware such as Audio/Video can also cause processing delay and gradual drift of audio from video. I haven't tried it myself, but I do know that virtualization of software doesn't always work optimally when dealing with real-time performance. Even running an OS natively (no virtualization) doesn't guarantee real-time performance. Windows is not a real-time OS. But capture does work on native Windows most often when we do capture and capture alone, not giving Windows anything else to do that might interrupt the flow of real-time processing that is video/audio capture. With virtualization, the host OS is already having to do tasks related to virtualization, so it has something else to do other than just capture, increasing chances the CPU is not always getting enough cycles to keep up with real-time.

Anyway, I would guess the primary suspect is virtualization. Options are to dual-boot on same hard drive, get 2nd hard drive for windows install and use some kind of boot selection software (e.g. Grub), or just a different machine dedicated to Windows. If you had a separate machine for capture, don't think it would take much. I think most of the heavy lifting is done by video and audio capture hardware. You just need to keep that machine's CPU free to keep up with the real-time task of capture.

Best of luck!
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  #9  
03-19-2019, 01:15 PM
latreche34 latreche34 is offline
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Yes audio drift is software/firmware related it has nothing to do with electricity or wires. Video and audio signals electrons travel at the same speed.
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  #10  
03-19-2019, 09:21 PM
keaton keaton is offline
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Although I think the virtual machine is the biggest obstacle in this, I think ridzoman was asking for my settings and I avoided that by saying I use the Virtualdub Guide written by sanlyn. If you haven't read that, I recommend it highly. Capturing with VirtualDub [Settings Guide] It explains what the settings mean and some situations to consider when deciding which settings to use. It's not one size fits all.

I had been using an ATI 600 USB for video capture and routed my audio direct from VCR to PC, bypassing USB. Not sure how important that is. Just what I chose to do. Here is what I see when going to Capture Menu and selecting Timing popup window from Capture mode in Virtualdub.

capturetiming.JPG

Bear in mind, I usually have a DataVideo TBC (i.e. external) in my path for capture, which really helps prevent any dropped/inserted frames. I don't think I've had one frame yet when using it. Although I think the Panasonic DVD pass-thru should also minimize those? My feedback thus far glossed over the assumption that you have rather stable timing of the input video signal. Naturally, if timing on the tape is rough, drift could happen even if the environment was capable of handing the real-time demands of capture. Then you would have to decide how you want to handle that (e.g. drop/insert frames and keep audio or keep video and stretch/contract audio).


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  #11  
04-02-2019, 05:22 PM
ridzoman ridzoman is offline
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Thanks all for your help. Erich's solution worked. I installed Windows 10 using Bootcamp on my iMac; installed VirtualDub and the Lagarith lossless coded (apparently Huffy doesn't "play well" with Windows 10). I used the same workflow -
  • Elgato USB capture device
  • JVC SR-MV40 pro s-vhs deck
  • s-video and composite audio out to Panasonic DMR-ES15 and then to capture device.
I used audio timing settings Keaton shared above, and Voila! Perfect capture! Thanks again
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  #12  
04-04-2019, 11:09 PM
keaton keaton is offline
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Sweet! I know the frustration of finding/fixing the one broken piece to the puzzle. Glad you stuck with it and found the magic recipe. In the end it's all worth it!

Very interesting about Lagarith working better for capture. The conventional knowledge of the forum is to capture with Huffyuv and convert to Lagarith later (if desired), due to Lagarith real-time performance. I am guessing that must be based on the XP/32-bit assumption. I can only speculate, but it would seem something in the 64-bit Huffyuv DLL (at least for Windows 10 anyway) is linking/calling to a library that is not nearly as efficient, compared to XP. Or perhaps it links/calls a different library than XP/32-bit does. I wouldn't know, but it would seem like there would be a way to build the Huffyuv DLL on a Windows 10 compiler. Maybe that has been done already, and it hasn't solved things. In which case, the Huffyuv code would need changes for Windows 10 (maybe 64-bit altogether) to use more efficient functions/libraries.

My understanding is that Huffyuv is a rather long-term type of lossless video codec, which should be around for quite some time. Not having a more efficient implementation in latest Windows may have an impact on it's status as a long-term archival lossless format? I don't plan to rely on Windows anymore than I have to. Unfortunately, most of the world still does. I guess you can always play it, so long as there is VLC. But to edit with it may not be as easy long term, because the old hardware and software will continue to be harder to come by. Or maybe it's OK for editing, just not great for real-time capture. Just rambling out loud...

Anyway, great to hear another success story! Happy capturing!
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