Quantcast VirtualDub luma histogram: eliminating left red tail gives washed out video? - digitalFAQ Forum
Go Back    Forum > Digital Video > Video Project Help > Capture, Record, Transfer

Reply
 
LinkBack Thread Tools
  #1  
10-08-2020, 03:27 PM
lmlampe lmlampe is offline
Free Member
 
Join Date: Jul 2020
Posts: 5
Thanked 0 Times in 0 Posts
The workflow: EP VHS (7 hour tape) --> AG-1980 (in-line TBC ON) --> TBC-1000 --> BVP-4 Plus --> ATI TV WONDER 2.0 USB --> VirtualDub on Windows XP desktop. Connections are with S-video cables.

When I start with the BVP's IRE and PTP knobs at default 12 o'clock, the histogram has lots of red on the left, but when I tweak them a little to correct the histogram, the video looks too washed out. I've just barely nudged the red out of sight. I actually prefer the darker look associated with the "bad" histogram.

In either case I'm making the same use of color and fleshtone knobs on the BVP.

So who do I believe: the histogram or my lying eyes? Do I just have bad taste in luma?

Also attached is another "good" histogram example but with BVP's black restore on and cranked up - if anything, looks the worst to me - the suit looks grey instead of black, and the video is maybe grainier.


Attached Files
File Type: avi test-ptp,ire at noon.avi (66.92 MB, 12 downloads)
File Type: avi test-ptp,ire adjusted-good histogram.avi (65.73 MB, 7 downloads)
File Type: avi test-ptp,ire adjusted-good histogram- plus black restore.avi (53.21 MB, 8 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  
10-08-2020, 03:42 PM
lordsmurf's Avatar
lordsmurf lordsmurf is online now
Site Staff | Video
 
Join Date: Dec 2002
Posts: 9,811
Thanked 1,674 Times in 1,455 Posts
If the monitor is calibrated, eyes are accurate, computers are stupid.

I'm not on my video system now, can't look at sample yet.

- Did my advice help you? Then become a Premium Member and support this site.
- Find television shows, cartoons, DVDs and Blu-ray releases at the TVPast forums.
Reply With Quote
  #3  
10-09-2020, 01:18 PM
BruceOlsen BruceOlsen is offline
Premium Member
 
Join Date: Jul 2019
Posts: 23
Thanked 2 Times in 2 Posts
I'm not an expert (rather far from it) but it looks to me like the frames are swapped, or reversed, or whatever it's called.
Note the right edge of the speaker's face when it moves sideways.
I can't recall how to fix this; I'm just restarting this after a long time away.
Reply With Quote
  #4  
10-09-2020, 03:08 PM
traal traal is offline
Free Member
 
Join Date: Jan 2016
Posts: 101
Thanked 19 Times in 17 Posts
Quote:
Originally Posted by BruceOlsen View Post
I'm not an expert (rather far from it) but it looks to me like the frames are swapped, or reversed, or whatever it's called.
Yes, the video is bottom field first for some reason.

To the experts: looking at the histogram, the green channel is crushed. Is this a problem, and is it best fixed during capture by setting brightness above the point where the red disappears in the histogram? The VirtualDub Settings Guide doesn't say.
Reply With Quote
  #5  
10-18-2020, 10:28 AM
lmlampe lmlampe is offline
Free Member
 
Join Date: Jul 2020
Posts: 5
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by traal View Post
Yes, the video is bottom field first for some reason.

To the experts: looking at the histogram, the green channel is crushed. Is this a problem, and is it best fixed during capture by setting brightness above the point where the red disappears in the histogram? The VirtualDub Settings Guide doesn't say.
RE: bottom field first -- if I apply the swap fields filter in VirtualDub, then the interlacing looks way off to me. Shouldn't that filter have fixed it? See the attached AVI.

RE: the histogram -- is there a way to see the histogram in VirtualDub post-capture? I only know how to bring it up in live capture mode.


Attached Files
File Type: avi fields_swapped.avi (66.94 MB, 0 downloads)
Reply With Quote
  #6  
10-18-2020, 12:01 PM
hodgey hodgey is online now
Free Member
 
Join Date: Dec 2017
Location: Norway
Posts: 870
Thanked 192 Times in 164 Posts
Quote:
Originally Posted by traal View Post
To the experts: looking at the histogram, the green channel is crushed. Is this a problem, and is it best fixed during capture by setting brightness above the point where the red disappears in the histogram? The VirtualDub Settings Guide doesn't say.
Usually, but it can be on the tape, or clipped by something in the capture chain as well, the video is going through several Analog->Digital->Analog conversions in this setup.

Swap fields won't change bottom field first to top field first. I'm not sure how to solve it in virtualdub, but with avisynth you can separate the fields and trim off the first one.
Reply With Quote
  #7  
10-19-2020, 05:58 AM
lordsmurf's Avatar
lordsmurf lordsmurf is online now
Site Staff | Video
 
Join Date: Dec 2002
Posts: 9,811
Thanked 1,674 Times in 1,455 Posts
BFF? How did that happen? That workflow is TFF.

Confirm VirtualDub version. TFF/BFF is a problem I've come across on VirtualDub2 captures.

- Did my advice help you? Then become a Premium Member and support this site.
- Find television shows, cartoons, DVDs and Blu-ray releases at the TVPast forums.
Reply With Quote
  #8  
10-19-2020, 12:36 PM
lmlampe lmlampe is offline
Free Member
 
Join Date: Jul 2020
Posts: 5
Thanked 0 Times in 0 Posts
VirtualDub 1.9.11 - my source is here.

The VHS was made by a tinpot short lived company. Is it possible it's BFF at the VHS source? If that's the case, is there anything I can do via software with the capture I have? Capture again isn't possible as the VHS is no longer in my possession.
Reply With Quote
  #9  
10-19-2020, 01:13 PM
traal traal is offline
Free Member
 
Join Date: Jan 2016
Posts: 101
Thanked 19 Times in 17 Posts
Quote:
Originally Posted by lmlampe View Post
The VHS was made by a tinpot short lived company. Is it possible it's BFF at the VHS source?
I captured a tape produced by a small production company like that, which had one segment that was BFF. I didn't fix it but I'll try hodgey's idea to use avisynth to separate the fields and recombine.
Reply With Quote
Reply




Similar Threads
Thread Thread Starter Forum Replies Last Post
VirtualDub, Histogram and encoding levels WarbirdVideos Capture, Record, Transfer 7 12-10-2019 07:38 PM
Red line in VirtualDub capture histogram Feedbucket Capture, Record, Transfer 3 01-23-2019 03:54 AM
Get video, histogram to show at same time in VirtualDub? stevevid Capture, Record, Transfer 1 09-15-2018 05:43 AM
VirtualDub level and histogram settings on captures? greeneagle Capture, Record, Transfer 2 07-13-2016 10:43 AM

Thread Tools



 
All times are GMT -5. The time now is 01:47 PM