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Audio sync on long VHS->USB capture
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bbutle01 [Avatar]
Newbie Private Message Joined: Aug 21, 2021 18:04 Messages: 1 Offline
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I have a project where I'm importing about a dozen family videos using a USB dongle attached to a VCR. Each tape is 6-8 hours long. The begginning of the capture works fine, but over time the audio gets further and further out of sync. By the end of it I'm about 5 full seconds out of sync.

I know how to 'fix it' after by chopping the video up and shifting the audio over but that's going to pretty time consuming to do for this much video. I'd really rather not edit/produce anything at all, just capture the clip and save the output. But this problem is driving me to look for other software.

Anyone have a fix for this? I've already checked in the source and it's synced. I've already tried a few other programs and they are fine, so it's not a hardware problem. They just all have their own limitations.

Is anyone else using some other software to capture?

This message was edited 1 time. Last update was at Sep 08. 2021 07:29

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StevenG [Avatar]
Contributor Private Message Joined: Jan 14, 2014 14:04 Messages: 419 Offline
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Much depends on the hardware and software you're using to digitize your files. Cheaper dongles don't do the job as well as real capture devices.

For best results, I recommend using the Diamond VC500 device to capture your analog video. There is third-party software that works well with it, and I recommend some in this tutorial. But I've gotten excellent results by using PowerDirector's capture with this device. The video it captures loads perfectly into PowerDirector and you will get no drift in the audio.

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Quote Is anyone else using some other software to capture?

USB sucks for real-time data transmission. The chip that the actual dongle uses contribues to that, by the mode of data connections and it's drivers capabilities.
USB transmission modes:

  • Asynchronous – The ADC or DAC are not synced to the host computer's clock at all, operating off a free-running clock local to the device.

  • Synchronous – The device's clock is synced to the USB start-of-frame (SOF) or Bus Interval signals. For instance, this can require syncing an 11.2896 MHz clock to a 1 kHz SOF signal, a large frequency multiplication.

  • Adaptive – The device's clock is synced to the amount of data sent per frame by the host



I use a firewire (IEEE 1394, ilink) connected encoder and it's perfect. Usually that is my older Canon miniDV camcorder, that has analog S-Video and Composite inputs (US higher end models have that, EU models don't). I have an extra firewire card in my computer.

This message was edited 3 times. Last update was at Sep 08. 2021 05:30

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BarryTheCrab
Senior Contributor Private Message Location: USA Joined: Nov 06, 2008 22:18 Messages: 6121 Offline
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USB is a tried and trustworthy method to capture analog video.
USB with NTSC sources, using S-video, capturing lossless, is superior to FireWire re:restoring.
Timing issues are usually related to crappy USB devices and lack of time base correction. HP Envy Phoenix/4thGen i7-4770(4@3.4GHz~turbo>3.9)/Nvidia GTX 960(4GB)/16GB DDR3/7,200rpm/w10x64---
Canon Vixia HV30/HF-M40/HF-M41/HF-G20/Olympus E-PL5. Tape capture using 4 VCR, TBC, Elite BVP4+, Sony D8 camcorder with TBC.
https://www.facebook.com/B-Gill-Cyber-Studio-6
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