SOLVED: Problem with colours capturing VHS

Do you have questions about Desktop Video, Converters, Routers and Monitoring?
  • Author
  • Message
Offline

Peter van Reijen

  • Posts: 10
  • Joined: Fri Jan 13, 2017 1:00 pm

SOLVED: Problem with colours capturing VHS

PostSun Mar 22, 2020 11:21 am

Hi everyone,

in the past I captured VHS tapes with a cheap device, in my case the Ion Video Forever. But the more I got interested in video the more quality I wanted to get out of those tapes. Of course (almost) the best quality you could get out of those analog tapes. So I bought a good vcr (VR1000) and TBC.

Because my computer was not always that stable ànd the Ion Video Forever device is not the best on market, I decided to step out of computer capturing solutions, but a standalone option. My set up: S-video output vcr -> TBC -> AJA S-Video To Dual BNC Cable -> BM Analog to SDI Converter -> BM Video assist. On the BM Video assist I record/capture on a SD-card.

The set-up works great, but I have some issues with the colours. It's overexposed. The bright colours are too bright. And the colours are not that colourful/contrastful as normal. In the attachment you can see the difference. Both are from the S-video output of the vcr. The good one is captures from the cheap device, and the overexposed one is captured out of the 'professional' solution.

I already tested the SDI ouput of the Analog to SDI converter with the BM Mini Recorder: same overexposed picture. So the problem is not the VIdeo Assist, but the Analog to SDI converter, or maybe the S-video splitter. I ordered an other one from an other brand to compare, but while waiting on that I thought let's ask you guys for help.

Maybe it is a fact that the Analog to SDI converter won't copy all the colour data? That would be a pity. I already connected the converter via USB with my computer and all the colour settings were okay (0).

I thought with this set-up I would get the best result out of my video tapes. Does someone recognize this issue?
Attachments
compared2 copy.jpg
compared2 copy.jpg (640.03 KiB) Viewed 205 times
compared1 copy.jpg
compared1 copy.jpg (539.84 KiB) Viewed 205 times
Last edited by Peter van Reijen on Mon Mar 23, 2020 3:10 pm, edited 1 time in total.
Offline
User avatar

Dmitry Shijan

  • Posts: 1143
  • Joined: Wed Sep 17, 2014 7:15 pm
  • Location: UA

Re: Problem with colours capturing VHS (Analog to SDI conv)

PostSun Mar 22, 2020 12:22 pm

It looks like something related to .mov container and superwhites analogue data clipping issue similar as described here viewtopic.php?f=3&t=109259#p603596 and here viewtopic.php?f=3&t=109259#p604678
Just put file to Resolve timeline, adjust Gain (or highlights only) down and you will see that all original data is still there.
All my custom made accessories for BMMCC/BMMSC now available here https://lavky.com/radioproektor/
Offline

Peter van Reijen

  • Posts: 10
  • Joined: Fri Jan 13, 2017 1:00 pm

Re: Problem with colours capturing VHS (Analog to SDI conv)

PostSun Mar 22, 2020 1:55 pm

Dmitry Shijan wrote:It looks like something related to .mov container and superwhites analogue data clipping issue similar as described here viewtopic.php?f=3&t=109259#p603596 and here viewtopic.php?f=3&t=109259#p604678
Just put file to Resolve timeline, adjust Gain (or highlights only) down and you will see that all original data is still there.


Thank you, I will take a look! It could be something with the container yes, but when I connect the Analog to SDI on the Mini Recorder, I also see overwhits.
Offline
User avatar

Dmitry Shijan

  • Posts: 1143
  • Joined: Wed Sep 17, 2014 7:15 pm
  • Location: UA

Re: Problem with colours capturing VHS (Analog to SDI conv)

PostSun Mar 22, 2020 6:44 pm

Peter van Reijen wrote:
Dmitry Shijan wrote:It looks like something related to .mov container and superwhites analogue data clipping issue similar as described here viewtopic.php?f=3&t=109259#p603596 and here viewtopic.php?f=3&t=109259#p604678
Just put file to Resolve timeline, adjust Gain (or highlights only) down and you will see that all original data is still there.


Thank you, I will take a look! It could be something with the container yes, but when I connect the Analog to SDI on the Mini Recorder, I also see overwhits.

Maybe not only AVI vs MOV container itself, but it is just how "honest" analog-to digital system works without automatic adjustment.
I noticed some options In capture card inputs and outputs to set gain during capture and also some unknown for me yet NTSC IRE option, but i didn't test yet if they affect clipping level.

Image
Image
All my custom made accessories for BMMCC/BMMSC now available here https://lavky.com/radioproektor/
Offline

Peter van Reijen

  • Posts: 10
  • Joined: Fri Jan 13, 2017 1:00 pm

Re: Problem with colours capturing VHS (Analog to SDI conv)

PostMon Mar 23, 2020 9:18 am

Hi Dmitry,

I already tried the IRE switch on the converter, but it doesn't fix it. On the Converters Setup I can also change the chroma or brightness levels, but it looks like the overwhites are burned in the video.
When I import the Prores files into Resolve and adjust the Gain or Hightlights down, nothing changes.
I can't understand why the picture is more colorfull and doesn't have overwhites with a cheap capture device, and do have with the AJA cable and BlackMagic converter..?!
Offline
User avatar

Dmitry Shijan

  • Posts: 1143
  • Joined: Wed Sep 17, 2014 7:15 pm
  • Location: UA

Re: Problem with colours capturing VHS (Analog to SDI conv)

PostMon Mar 23, 2020 1:41 pm

This is bad. Seems some device in your chain irrevocably trims superwhites data.
All my custom made accessories for BMMCC/BMMSC now available here https://lavky.com/radioproektor/
Offline

Peter van Reijen

  • Posts: 10
  • Joined: Fri Jan 13, 2017 1:00 pm

Re: Problem with colours capturing VHS (Analog to SDI conv)

PostMon Mar 23, 2020 3:09 pm

SOLVED! Oh yeah I am so happy :D On my TBC I have a gain control switch and when I set it on 'on', the overwhites are gone.
Offline
User avatar

Dmitry Shijan

  • Posts: 1143
  • Joined: Wed Sep 17, 2014 7:15 pm
  • Location: UA

Re: SOLVED: Problem with colours capturing VHS

PostMon Mar 23, 2020 6:01 pm

Great! By the way i also use "auto gain" in Time Base Corrector because image just looks better with it. I'll test if it damage superwhites data when turned off. Very interesting discovery...
All my custom made accessories for BMMCC/BMMSC now available here https://lavky.com/radioproektor/

Return to Post Production

Who is online

Users browsing this forum: No registered users and 9 guests