Quantcast How should the SMPTE color bars be used on VHS? - digitalFAQ Forum
  #1  
08-16-2019, 10:49 AM
ELinder ELinder is offline
Premium Member
 
Join Date: Oct 2018
Posts: 197
Thanked 32 Times in 26 Posts
For the first time I've been given a tape that the dub house put SMPTE color bars and tone on before the main material during the original transfer. My question is for the experienced hands at analyzing these. How good could or should they be when capturing from a VHS source? What would you correct with them in AviSynth before going to the program portion for filter corrections? Captured with JVC HR-s7800U with TBC/NR on --> Datavision TBC-4000 --> Diamond VC500 via S-Video cables.

Erich


Attached Files
File Type: avi TBC-on-capture-01-bars-and-tone.avi (56.73 MB, 15 downloads)
Reply With Quote
Someday, 12:01 PM
admin's Avatar
Ads / Sponsors
 
Join Date: ∞
Posts: 42
Thanks: ∞
Thanked 42 Times in 42 Posts
  #2  
08-17-2019, 06:03 PM
lordsmurf's Avatar
lordsmurf lordsmurf is offline
Site Staff | Video
 
Join Date: Dec 2002
Posts: 11,711
Thanked 2,140 Times in 1,841 Posts
More often than not, I find that color bars were just the byproduct of equipment used in the initial dubbing/recording setup, and not something by which the content was calibrated against. The inclusion wasn't intentional, and is in fact just lazy use of the gear, not turning off pattern generators (when available). I almost always disregard those.

Those bars in your example have a lot of chroma noise. Check if line TBC engaged, consider enabling the VCR NR filters as well (picture mode = NORM/AUTO) Also check s-video cables.

- Did my advice help you? Then become a Premium Member and support this site.
- For sale in the marketplace: TBCs, workflows, capture cards, VCRs
Reply With Quote
  #3  
08-17-2019, 06:41 PM
ELinder ELinder is offline
Premium Member
 
Join Date: Oct 2018
Posts: 197
Thanked 32 Times in 26 Posts
This tape was recorded by the post house who did the editing/color corrections, so I'm hoping the bars are meaningful with regard to the content, but of course since it was over 20 years ago I have no way of knowing. As I said in the post, that capture already has the VCR line TBC and NR turned on as well as going thru the TBC-4000. I also have a number of different s-video cables I've tried, but that's pretty typical of the captures I've always gotten since I bought the units from you.

What would you suggest? Do I have a problem I need to take care of?

Erich
Reply With Quote
  #4  
08-17-2019, 06:45 PM
lordsmurf's Avatar
lordsmurf lordsmurf is offline
Site Staff | Video
 
Join Date: Dec 2002
Posts: 11,711
Thanked 2,140 Times in 1,841 Posts
I would probably still disregard it.

Analog-domain correction was never precise, and is quaint compared to modern NLEs.

Sure, if you really want to fiddle with proc amp controls, you can attempt to capture it perfect(ish) to the pattern. But I still bet the content isn't really that perfectly graded.

- Did my advice help you? Then become a Premium Member and support this site.
- For sale in the marketplace: TBCs, workflows, capture cards, VCRs
Reply With Quote
  #5  
08-17-2019, 06:51 PM
ELinder ELinder is offline
Premium Member
 
Join Date: Oct 2018
Posts: 197
Thanked 32 Times in 26 Posts
OK, so in that case even if the grading of the pattern and the show are not related, is the chroma noise you're seeing still a problem? I've been going under the assumption that what I've been getting is normal since I've seen it since the beginning with this gear.

Erich
Reply With Quote
  #6  
08-17-2019, 07:01 PM
lordsmurf's Avatar
lordsmurf lordsmurf is offline
Site Staff | Video
 
Join Date: Dec 2002
Posts: 11,711
Thanked 2,140 Times in 1,841 Posts
All tapes have chroma noise, inherent to the format. Still images can make it look worse than actuality. Just attach a small clip, and converted to 4:2:2 H.264 would be easier (smaller size, I can view that on my non-video systems for quicker response).

- Did my advice help you? Then become a Premium Member and support this site.
- For sale in the marketplace: TBCs, workflows, capture cards, VCRs
Reply With Quote
  #7  
08-17-2019, 07:12 PM
ELinder ELinder is offline
Premium Member
 
Join Date: Oct 2018
Posts: 197
Thanked 32 Times in 26 Posts
The attached clip in the first post is a direct stream HuffYUV copy. I'll post an h264 version tomorrow. This is the first time I've seen you ask for a processed version.

Thanks,
Erich
Reply With Quote
  #8  
08-17-2019, 07:19 PM
sanlyn sanlyn is offline
Premium Member
 
Join Date: Aug 2009
Location: N. Carolina and NY, USA
Posts: 3,648
Thanked 1,265 Times in 972 Posts
If you think the color bars on VHS tapes will make it easier to get good color and help you avoid learning about color, forget it. A proc amp won't help much, either, since your novice color skills are assuming that you can correct red, green, and blue (you can't. Correction in YUV is very difficult and clumsy) -- and what do you do when every scene in your VHS changes color balance and luma range? Do you stop the capture every 30 seconds to reset your proc amp? No way.

There's no replacement for understanding color theory and principles, and no push-button killer software that does it for you. Go to your nearest movie theater, watch old and new color work, and see what real-world results the pro's get. Stay away from YouTube (haven for the clueless, con artists, and wannabees). Stay away from megabuck color software until you can learn to use the basics in Avisynth and Virtualdub (which happen to be pretty decent for most of us). Get a long-standing industry standard on the subject: https://www.amazon.com/Color-Correct...s=books&sr=1-2.

There are no workarounds.
Reply With Quote
  #9  
08-17-2019, 07:23 PM
lordsmurf's Avatar
lordsmurf lordsmurf is offline
Site Staff | Video
 
Join Date: Dec 2002
Posts: 11,711
Thanked 2,140 Times in 1,841 Posts
A bit harsh sanlyn, even if mostly accurate.

Premiere has long been my preference for color grading, but I do want to learn DaVinci (free version) at some point.

For easy cheat methods, I rely on VirtualDub, and Avisynth. Each is more powerful that I take advantage of, hence the cheat comment, but for power I again use Premiere.

I really don't color grade that much anymore, my main focus is getting footage to the point where that can happen. Capturing and restoration.

There are some good tutorials for color correction on Youtube, but equally as many bad (some clueless). Remember that any schmuck that make a Youtube video, so credentials matter.

- Did my advice help you? Then become a Premium Member and support this site.
- For sale in the marketplace: TBCs, workflows, capture cards, VCRs
Reply With Quote
  #10  
08-17-2019, 08:03 PM
ELinder ELinder is offline
Premium Member
 
Join Date: Oct 2018
Posts: 197
Thanked 32 Times in 26 Posts
Sanlyn, go back and read my first post. You've made a lot of assumptions not based on what I actually wrote.

I'm asking how valid they are and if and how to add them to the workflow. I'm not looking for nor asked about any kind of workaround or some kind of magic button to press. And for the record, I already have that book and am slowly working my way thru it. Not everyone has your years of experience.

Erich
Reply With Quote
  #11  
08-17-2019, 08:59 PM
lordsmurf's Avatar
lordsmurf lordsmurf is offline
Site Staff | Video
 
Join Date: Dec 2002
Posts: 11,711
Thanked 2,140 Times in 1,841 Posts
Quote:
Originally Posted by ELinder View Post
I already have that book and am slowly working my way thru it. Not everyone has your years of experience.
When you get done, I'd appreciate some Cliff's Notes, good overview, your opinion on the most helpful pages/chapters. I know how to correct, but it never hurts to learn more. It's on my Amazon wish list, but I've just not had time to read it, so not yet bought it.

Funny thing about experience ... you get rusty, forget stuff, refreshers never hurt.

At any rate, to get back on-topic, without seeing the full video, I'm just not inclined to believe it's perfect as dubbed. George Lucas is famous (and infamous) for constantly going back and re-coloring Star Wars. Sometimes for the better, sometimes for the worse. But my point is that correction can be improved. So a test pattern on an old VHS should never be considered the epitome of accuracy.

I've taken a look at the pattern. I do see tape noise, but it could be merely being critical of an old tape. Sometime, even with TBC, good cables, NR, it still has some degree of noise. That's determined by testing, just finding the best possible settings combo. You're probably fine, just double-check everything to be sure.

- Did my advice help you? Then become a Premium Member and support this site.
- For sale in the marketplace: TBCs, workflows, capture cards, VCRs
Reply With Quote
  #12  
08-18-2019, 07:09 AM
sanlyn sanlyn is offline
Premium Member
 
Join Date: Aug 2009
Location: N. Carolina and NY, USA
Posts: 3,648
Thanked 1,265 Times in 972 Posts
Quote:
Originally Posted by ELinder View Post
Sanlyn, go back and read my first post. You've made a lot of assumptions not based on what I actually wrote.
I thought I answered the first time, but thanks for further qualifying your question. I'll go back and try again:

Quote:
Originally Posted by ELinder View Post
For the first time I've been given a tape that the dub house put SMPTE color bars and tone on before the main material during the original transfer. My question is for the experienced hands at analyzing these. How good could or should they be when capturing from a VHS source? What would you correct with them in AviSynth before going to the program portion for filter corrections? Captured with JVC HR-s7800U with TBC/NR on --> Datavision TBC-4000 --> Diamond VC500 via S-Video cables.
SMPTE color bars on VHS tapes were used to calibrate the duplication hardware, not to color grade the VHS content. The bars helped to ensure that the (overall) tape volume levels and luma/color range fell within a certain constraint that wouldn't blow up your CRT TV or their playback gear. The test patches don't say that the color balance in every part of the tape is "correct", and in fact it seldom is.

I've had a few tapes where the color looked pretty decent throughout (of those with color bars, the bars didn't seem to have anything to do with it), but that's rare and they still needed some correction to satisfy us OCD'ers. I've seen a few threads in other forums where people attempted to use the color bars to determine color grading values for various scenes in various tapes. The "corrected" samples they posted had terrible color correction. In most cases the poor guys obviously didn't know what they were doing, and much of the time they were apparently using uncalibrated monitors. You would also have results such as corrected (unquote) skin tones that looked like terminal liver disorders, and frames with bluish brights and greenish blacks that were transformed into clipped brights, reddish brights, and purple blacks. The next scene would have entirely different problems. Also, those color bars were set up for CRT displays, not for YUV capture.

Years ago I tried using the colorbars to set capture levels but ended up readjusting levels within a few seconds or minutes of playback. Except for a very few old tapes that had obvious and consistent YUV tint problems from start to finish, I gave up long ago on trying to correct VHS color during capture. it's an exercise in clinical masochism. I do have a PA-100 proc amp that I use for checking and setting signal levels (which I still re-check with VirtualDub's capture histogram). Color problems with VHS aren't linear and are seldom consitent from minute to minute; I've found retail movie transfers to be among the worst. Often you'll need curves filters to make corrections -- those color wheels aren't precise enough.

Quote:
Originally Posted by ELinder View Post
I already have that book and am slowly working my way thru it.
Good show. I have that one too and settled on it after trying others. It's been helpful for everything from Avisynth and VirtualDub to AfterEffects, ColorFinesse, and even Photoshop. It's a thick book for sure, but specific and thorough. I still bring it to hospital and clinic waiting rooms and it sits in an open shelf above my computer work desk for quick access.

Last edited by sanlyn; 08-18-2019 at 07:22 AM.
Reply With Quote
  #13  
08-18-2019, 08:58 AM
ELinder ELinder is offline
Premium Member
 
Join Date: Oct 2018
Posts: 197
Thanked 32 Times in 26 Posts
Thanks both of you, that's exactly the kind of first hand experience that makes this site so valuable.

As for re-colored films, I just watched the Blu-ray release of Disney's 20,000 Leagues Under the Sea - a favorite film of mine. Yuck! The "restoration" consisted of removing the film grain and changing the color balance so badly I'll happily go back to watching the lower resolution original transfer DVD version in the future.

Erich
Reply With Quote
Reply




Similar Threads
Thread Thread Starter Forum Replies Last Post
Hanover bars: Should they always look the same? KingBuZZo Capture, Record, Transfer 0 05-19-2019 09:02 AM
AVT-8710 alternatives, wavy distortions, color bars? cpayne825 Capture, Record, Transfer 20 12-29-2018 05:27 PM
Working with color bars on old tapes? koberulz Restore, Filter, Improve Quality 8 12-06-2017 06:30 AM
Datavideo TBC-1000 has no color bars? videonut Video Hardware Repair 2 04-02-2014 09:24 AM
Black bars jrnyhead Encode, Convert for discs 3 04-07-2004 12:26 PM

Thread Tools



 
All times are GMT -5. The time now is 03:25 PM