VCR to digital, Media Express, audio out of sync

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Amund Raknes

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VCR to digital, Media Express, audio out of sync

PostTue Mar 31, 2015 8:52 pm

Hi!
I´ve been trying to digitise my VHS tapes lately, and I´ve run into a problem using Blackmagic Media Express. I want to capture the video from the VHS, which seemed to go well.

However, upon playback I discovered that there´s a severe video delay that increases the longer into the video I get.

I´ve tried all the available capture formats. Each one creates a video delay, but the length of the delay differs.

I did a trial of many the formats, and in a 15 minute test these were the video delays (by the end of the video):


ProRes HQ: 32 second delay
ProRes LT: 6 second delay
ProRes Proxy: 12 second delay (oddly)
Uncompressed YUV 8-bit: More than 30 seconds delay
DVCPRO50: 2 seconds


So as you can see the delay is catastrophic pretty much all over the board.

Is this the fault of my mac?
Is this the fault of the program?
Something else? Your help is very much appreciated!

Specs of my mac:
Processor: 2,4 GHz Inter Core i5
Memory: 8GB 1600 MHz DDR3

BlackMagic Media Express version: Version 3.3.2, Desktop Video 10.3.7

EDIT: I´m using the BlackMagic Intensity Shuttle as the middleman between my VCR and my mac.
EDIT 2: I realise I´ve made it sound like the audio lags behind the video, while in reality it is the video that lags behind the sound. So it´s a video delay, not an audio delay.


Thank you very much!
Amund Raknes
Last edited by Amund Raknes on Thu Apr 02, 2015 12:48 pm, edited 2 times in total.
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Colin Barrett

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Re: VCR to digital, Media Express, audio out of sync

PostTue Mar 31, 2015 9:34 pm

When you state "VCR to digital" what specific device is being used to effect the conversion to digital? It is highly likely that this hardware interface is the source of the problem.
Blackmagic Teranex 2D, Ultrastudio Express, Intensity Shuttle (Thunderbolt), Two H.264 Pro Recorders (Mac OSX) & lots of old VTRs used for digital archiving of legacy video formats for major libraries, broadcasters, universities and public archives.
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Amund Raknes

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Re: VCR to digital, Media Express, audio out of sync

PostTue Mar 31, 2015 10:31 pm

I´m using the Intensity Shuttle :) Hooked up via the YrCrB ports if that matters.
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Peter_r

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Re: VCR to digital, Media Express, audio out of sync

PostWed Apr 01, 2015 12:51 am

I can try this next week on my mac and Thunderbolt intensity box. I've captured hours worth from LD in the past without audio drift, maybe it is a bug in the new version of the software. Are you running the latest versions?
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Adam Simmons

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Re: VCR to digital, Media Express, audio out of sync

PostWed Apr 01, 2015 4:53 am

Is your VHS source playing through a timebase corrector?

In Media Express do you have 'Stop capture if dropped frames detected' ticked. I've seen it go out if sync if there are dropped frames but you tell it to ignore them
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Colin Barrett

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Re: VCR to digital, Media Express, audio out of sync

PostWed Apr 01, 2015 10:59 am

Peter_r wrote:I can try this next week on my mac and Thunderbolt intensity box. I've captured hours worth from LD in the past without audio drift, maybe it is a bug in the new version of the software. Are you running the latest versions?


I'm running the latest version of Desktop Video software on three Mac systems and only last week I ran several long-form VHS and S-VHS tapes through a TBC and then into Media Express (via Teranex 2D) without any sync problems whatever. I don't think the Desktop Video software is the problem, to be honest - especially since you say the sync error is cumulative as the running time increases. That very much sounds like a hardware interface / converter issue to me.
Blackmagic Teranex 2D, Ultrastudio Express, Intensity Shuttle (Thunderbolt), Two H.264 Pro Recorders (Mac OSX) & lots of old VTRs used for digital archiving of legacy video formats for major libraries, broadcasters, universities and public archives.
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Amund Raknes

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Re: VCR to digital, Media Express, audio out of sync

PostWed Apr 01, 2015 11:20 am

Peter_r wrote:I can try this next week on my mac and Thunderbolt intensity box. I've captured hours worth from LD in the past without audio drift, maybe it is a bug in the new version of the software. Are you running the latest versions?

Running the latest versions yes.
Adam Simmons wrote:Is your VHS source playing through a timebase corrector?

In Media Express do you have 'Stop capture if dropped frames detected' ticked. I've seen it go out if sync if there are dropped frames but you tell it to ignore them

Not using a timebase corrector I believe? Is that an external device or does some VCR´s have them built in? From what I read online I only need one if I want to mix an analog and a digital signal though?

I do have "Stop capture if dropped frames detected" ticked.

Appreciate the help!
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Amund Raknes

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Re: VCR to digital, Media Express, audio out of sync

PostWed Apr 01, 2015 2:01 pm

So neither of you thinks it has anything to do with the specs of my mac, but rather the Intensity Shuttle? My mac should be fine even capturing high quality ProRes?

Side note: why does each comment I make have to be approved before its shown?
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Tony Rivera

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Re: VCR to digital, Media Express, audio out of sync

PostWed Apr 01, 2015 9:46 pm

Amund Raknes wrote:Side note: why does each comment I make have to be approved before its shown?

Newly registered users have their first few posts in moderation. Until you clear that, all posts are moderated. I believe you should be able to post before prior approval now.
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Peter_r

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Re: VCR to digital, Media Express, audio out of sync

PostThu Apr 02, 2015 3:21 am

I tested last night, I get no problems and I am capturing on a 2011 macbook pro.
I think some screen captures of your settings might help us roubleshoot.

(Command-Shift-4 to screencap to the desktop, and just rubber-band around the area you want to capture)
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Amund Raknes

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Re: VCR to digital, Media Express, audio out of sync

PostThu Apr 02, 2015 11:06 am

Peter_r wrote:I tested last night, I get no problems and I am capturing on a 2011 macbook pro.
I think some screen captures of your settings might help us roubleshoot.

(Command-Shift-4 to screencap to the desktop, and just rubber-band around the area you want to capture)

Sure! Here you go :) Capture settings and general settings for Media Express.
https://drive.google.com/file/d/0B1_s6q ... sp=sharing
https://drive.google.com/file/d/0B1_s6q ... sp=sharing
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Amund Raknes

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Re: VCR to digital, Media Express, audio out of sync

PostThu Apr 02, 2015 12:50 pm

I realise I´ve made it sound like the audio lags behind the video, while in reality it is the video that lags behind the audio. So it´s a video delay, not an audio delay. So at the end of each video there is a short sequence with no audi because the audio is ahead of the video.
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Denny Smith

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Re: VCR to digital, Media Express, audio out of sync

PostSat Apr 04, 2015 7:13 pm

You have lost audio/video sync. When converting VHS tapes,especially, if you are using a consumer VCR, you need a time base corrector, as Colin suggested, to keep the audio and video in sync, and the both in sync to the Shuttle. ATBC is an external processor between the VCR and Shuttle, to correct and re lock the time code, which helps lock the video and audio signals from drifting, and have a continious TC to Shuttle to process analog signal to digital.
Denny Smith
SHA Productions
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NigelB

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Re: VCR to digital, Media Express, audio out of sync

PostTue Nov 26, 2019 10:56 am

I have also been experiencing problems with audio sync capturing VHS (SD) to lossless AVI (10 bit YUV) with Media Express. My set-up is VHS deck > Datavideo TBC-1000> composite input of Blackmagic Analog to SDI Mini Converter> Decklink Mini Recorder.

All was fine up until recently, I have captured a large number of tapes with no sync problems so I was convinced it wasn't a hardware issue.

On examining the problem files in MediaInfo, they showed shorter durations for the audio portion of the file.

I have updated the Nvidia graphics driver on my PC and the issue seems to have been solved. The first tape I captured (one that gave me audio sync problems yesterday) has no audio sync problems in the resulting AVI. I hope this continues to be the case and also is of some help to anyone else out there experiencing problems.

Nigel Bryant
Audiovisual Digitisation Officer
University of Bristol Theatre Collection
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NigelB

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Re: VCR to digital, Media Express, audio out of sync

PostThu Nov 28, 2019 12:30 pm

OK, I spoke too soon.

Although the next 3 tapes I ran were fine, the problem has now returned. Audio out of sync, MediaInfo showing shorter duration of audio portion of the AVI. It seems to be this odd intermittent fault. Any suggestions? I've tried several things now - I've even made my digitising PC a dedicated station with no other software running during the process and no connection to the internet.

Thanks,

Nigel Bryant
Audiovisual Digitisation Officer
University of Bristol Theatre Collection

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