Histogram not working in VirtualDub?
 

I'm using an ATI 600 USB on Windows XP with Vdub 1.9.11. I wanted to reference the histogram before starting captures to check levels but it never displays any information. Is there something specific that must be done for it to work, and is it even worth using the histogram in the first place? I've read conflicting opinions about its usefulness. To me it seems like a good idea to make sure highlights aren't blown out, etc. before capturing instead of trying to fix in post.

I have the same issue with my Histogram but using Pinnacle 710-USB2, XP and VD1.9.11.
Did you work it out?
I'm tempted to use values I've seen in tutorial videos or there abouts:

• Brightness 164
• Contrast 68
• Hue 128
• Saturation 128
• Sharpness 128

Just FYI, I consider overly relying on histograms to be naive (newbie, novice, green).

It reminds me of family members that stare at the rearview camera screen in the car, while backing up, instead of actually looking around and into the mirrors. Those cameras are indeed useful, but it doesn't inform you of your surroundings. It gives a very incomplete picture.

That's basically a histogram, giving a very incomplete understanding. It was never intended to be a video god that must be appeased, as some seem to think.

To make matters worse, it's just not all that reliable. Usability can vary based on card and OS.

In most cases, you won't be able to fix crushed blacks or blown out whites post-capture, so I wouldn't rely on that being an option.

One thing you could do if the histogram isn't working is to run the signal through a hardware waveform monitor, but then you'd also need to combine it with a hardware proc amp so that you could actually change the levels if you see that they are outside of the legal range. The other thing is that there aren't a whole lot of S-Video waveform monitors, but you could just run the luma wire through a composite waveform monitor still give appropriate readings as though it were a composite signal.

I've also heard there are various tricks to get it to pop up such as needing to be in "prievew" mode or something like that, but I haven't played around with that myself.

I would still consider myself a novice. I've never been very confident adjusting settings like this even on TVs. I remember arguments with my brothers over contrast and brightness growing up. We had very different ideas of what looked "good".

The first part of your reply stood out to me more. Is that to say I should focus on the blacks not being too black and whites not being too white as priority?

Does it also mean settings like Colour, Hue, Saturation and Sharpness can be left default and/or corrected post capture?

Color, Hue, and saturation are pretty easy to adjust in post. It's the luma that if above a certain level all get assigned the highest value (digitally) and same goes for blacks - ie values below 7.5IRE are all assigned to black. Technically you can also have colors that clip too, but this is much less common to observe in practice.

So yes, I'd say the priority is to not have white areas too white and black areas not too black in the capture stage, but doing that is kind of hard without a waveform monitor.

Yeah I'd say to at least prevent keep the blacks and whites from being crushed during capture, everything else should be left at default, especially sharpness.

Here is an example where I adjusted the proc amp of my capture card before capturing vs me leaving the brightness and contrast settings at their default values.

Intentionally boosted the contrast to be 200% afterwards so the effect it has on the blacks is more noticeable.

Attachment 19522 Attachment 19523

Ouch, considering my earlier post and misunderstanding of the histogram in virtual dub. haha

for the record though my histogram doesn't show up if VD is in Overlay mode. so it has to be in preview mode for me. but i'm sure it's likely not as simple as that.

Once I understood that my TBC was not sharing all the information with the histogram, I learned the histogram is still important and can be useful. In my recent experience though I learned the valuable lesson of luma preservation and how some TBCs only pass along the "legal" levels, so even if the histogram doesn't show red, you can still be crushing your whites/blacks. So to see this in my setup, the histogram is basically bunched up to a vertical edge on the right or left side, I noticed this from the get go but coming from the digital photography world I was still thinking the histogram was showing me all the data in the tape and the clipped bits were just lost when the tape was recorded. this was wrong though because It was just the TBC not passing all the outside range luma values that were captured.

between our eyes and the histogram is basically what us basic members have to rely on to get the levels right before capture, since I'm sure a lot of use don't have the advanced tools others around here do. I don't even know what a waveform monitor is.

Ha, this is my issue. I would have said the bottom image (darker) looks better than the top image (greyer).

However, I can see what you mean about the blacks, they are voids. No detail visable and I guess that information gets lost if it is captured this dark?

Should I try and find a sweet spot in the middle, even if it looks (to me) slightly greyer than I would normally have it?

Yes that information gets lost, well for me it does. I use a Pinnacle 510 that can only capture between 16 and 235. Anything below 16 gets crushed to full black, and anything above 235 gets clipped to full white.

Need to capture with the brightness set to -10 and the contrast set to +18 so that everything is being captured with legal levels. Granted the external TBC I use by default lowers the whites so they aren't clipping as much, so it helps.

Can of course adjust them in post, could reverse the proc amp adjustments later if I wanted to for example.

That's something new I should consider, my capture device is the Pinnacle 710 (LS).

I've now added a Full Frame TBC (new arrival) and I was playing with it the other day. Amazing! My old capture of my brothers wedding was horribly out of sync. With the new TBC, my most recent capture was zero for both Dropped and Inserted Frames!

However, the levels were not great which had led me here. I need to play around with its levels and also VirtualDub's much more I think...

I've added my workflow to my signature now so it can follow me around.

Edit: Hmm where is my signature!?

With the TBC included? How does it look with the TBC and without?

I know with my Cypress TBC in the chain the whites get legalized a bit, not perfect but better than it without it in the chain. Seems to not affect the blacks at all.

Though by default the image is oversaturated, have to decrease the saturation using the TBC's proc amp by three stages to more closely match how the saturation is without in the chain.

So basically I leave the Cypress' proc amp controls at their default values minus Saturation/Color which is decreased by -3

For the Pinnacle, keep the brightness at +10 and the contrast at -18, leave everything else at default

When the CTB-100 first arrived, it had its previous owners settings and it looked quite good.

Then I reset it. :smack: Now it looks quite flat. The buttons presses are quite imprecise though, no read out or anything. I'm not even sure how many presses is the maximum or minimum.

So far, I've arrived at the following conclusion regarding the CYP CTB-100 controls:

Contrast = One or two + presses.
Brightness = One or two + presses.
Colour = Up to five + presses.
Tint = NTSC Only (I'm PAL)
Sharpness = Default (No noticeable difference + or - that I could see)

It was after doing this test above that I tried the Histogram in VirtualDub only to find it wasn't working. I then came here.
My VDub levels are still currently all default.

I've never seen this version of a Cypress that had bad unity ("0" settings, "off"), at least not that I recall. So you're probably adjusting the video (proc amp) to your non-calibrated monitor.

PAL has tint, and tint issues. PAL doesn't have a chroma problem exemption.

I've never had the CYP CTB-100, and not for lack of trying, but it should not be different that the other Cypress models of the same lineage. Even the "black" models, for all their warts, still had good proc amps. Yes, weenie (compared to other proc amps). And yes, not smooth at changing. But not wrong.

There's always a chance that the unit is bad. You did, after all, buy it as a "for parts, not working" eBay auction. It's not buying, it's gambling. Now, I thought you'd won that bet, but maybe not. Doubts are warranted. Remember that many (most?) eBay sellers are liars, especially when it comes to functional gear. Too often, known-bad gear is sold with the lame descriptions of "I don't know if it works". Then, by listing as "parts", the seller can be protected against returns/refunds (if they did it correctly). Shady place. I warn about eBay all the time, but not everybody listens. Still, I hope it's not bad, just user error (correcting to non-calibrated monitor).

Note: Aya_Rei has a different Cypress lineage. Those can have unity drift, but it generally takes heavy use (and abuse) to get there. But we're talking -/+5 or less, not -/+10 to 20. Anything that extreme is content.

I'll have to test the Tint, I didn't bother until now because the Manual said NTSC Only.

I did not realise those controls are considered a type of proc amp.

That is some excellent deductive reasoning haha I guess some of you must have been watching the same eBay listing!

It was a gamble, true but it seems to be working. No weird ghosting on the blue screen like those 2010+ chipsets, I'm getting zero dropped or inserted frames (I tested it on an old copy of a VHS of my brother's wedding that had previously been jittery and out of sync by the 1-hour mark).

My monitor is definetly non-calibrated. I think that is the weak link here. I am not very good with that sort of thing, like I mentioned before. Getting the levels improved is my next step and what brought me to the Histogram and this thread. I think I need more practice doing it manually.

In lieu of a working Histogram, how would you calibrate a TBC, VirtualDub and monitor?

I often monitor eBay, as it's like watching a trainwreck. Lots of suckers getting taken to the cleaners there. Several of us regularly discuss auction listings in private, sometimes in public.

I'm not convinced it's dud either, but it's an unknown. As a novice/newbie, you have no way to confirm or deny. It's messy. (Also a reasons I sell gear, as I can remove unknowns. One less variable to deal with.)

You bet on the TBC. This time, I bet on this snafu being the uncalibrated monitor.

For video calibration, on a monitor, I use a mix of Avia and Spyder/X-Rite. Spyder first, but it's mostly for print calibration. Avia tunes it more, as it's video tools. I've done it with Avia only, it's just a bit more fiddly. Part of this also depends on the quality of monitor. I only use LG and ViewSonic, largely due to calibration quality.

My desktop monitor is a ASUS ROG SWIFT PG27VQ, I used to game. It has loads of settings, mostly unused.
My laptop is a CLEVO W870CU 1080p (love this laptop), much less information on the monitor though.

I'll see how they perform with this Avia.

The TBC outputs coloured bars when there is no signal, would this be part of the calibration process?

My TBC does the same thing, are you wondering if LS uses the no signal color bars as a means to test calibrating his monitor?

If so, then only he can answer that of course.

My TBC has a color bar generator too but if someone wanted to calibrate a screen with a test pattern they would do it with one coming off of a dvd or something like that. I think the test pattern off of a TBC is supposed to be to check your TBC.

You will see some crazy buys on eBay if you watch it for a while. You’ll see the same stuff come back up sometimes.

So, I calibrated my monitors (they were pretty much fine) one is not as bright as the other but that's age and tech.

Then, for reasons unknown, the Histogram just started working. I tested a VHS and I got a slither of red at either end, barely visable, it must be right on that 16-235 range.

Here is the unexpected thing, all the VDub Levels are 0, i.e. default

Including the TBC, they are also set to default.

I think this looks best but I had expected to raise some levels a little bit here or lower them a little bit there.

Is this typical? :unsure:

Ok so, those "slithers" I mentioned in my previous post got me thinking, "this is too good to be true".

I tried to intentionally make them go into the red area but they never do. It is never more than a slither. Just like in this post I found: https://www.digitalfaq.com/forum/vid...am-blacks.html
https://www.digitalfaq.com/forum/att...am_3_close-jpg

I essentially have the same issue as @kingbean but with both black and white levels.

What I understood from this post is that, my card cannot capture 0-16 or 235-255 ranges.

But what I could not work out is, is this an issue, and if so, how to remedy?

It may be an issue if your card is presented with a signal brighter than 235, darker than 16, or both.

If brighter than 235, reduce brightness. If darker than 16, increase brightness. If it's both, reduce contrast until both fall within the acceptable range, finally tweaking brightness and contrast to balance both neatly within the window. It's about juggling brightness and contrast.

But also play around with the settings, watching both the picture and the histogram. Deliberately increase brightness so the lighter greys go white. Deliberately reduce brightness so the darker greys go black. See how that agrees with the histogram, which it should.

Even when I deliberately play around with the brightness and contrast I get no more than that small red line as pictured above. I can see the Histogram shifting around, stretching and moving, so it is reacting to the change in levels but it's hiding the full picture from me.

I guess I'll just have to tweak it until there is no red line or stop when the moment the red line first appears.

I'm trying to trust me eye more too but I am beginner at that.

Hi so I'm not an expert but this is what happens to me as well. It is my understanding that it is because of my frame TBC (in my case a BVTBC8) only passes what it figures to be legal values to the capture card and since the brightness/contrast settings in virtual dub only effect the post TBC and digital domain signal, you can never get it to reflect more than those "slithers" as you call them. The only solution I know of is to trust my eyes to see if it looks like the whites or blacks are being clipped, also often evident in the histogram if the far right or far left is completely vertical implying theres more "data" in the red that the capture card just isn't seeing, and then compressing the luma values using my proc amp settings on the frame tbc itself (in the analog domain, PRE capture card) if that makes sense. Sometimes the blacks or whites are just crushed/clipped no matter what I do, in which case I assume that original recording is just like that to begin with. But if my histogram has somewhat of a gradual slope on the right and left, I usually can assume nothing or at least very little is being clipped. Sometimes this results in a rather flat image, so theres certainly a balance to it, but I suppose the histogram could later be expanded in post whereas if those luma values get clipped that information is lost forever.

if I'm wrong people can correct me. I'm no expert. I tried making a similar thread and also recall not really getting a clear cut solution/explanation. But this is my current understanding. hope it helps.

for the record here was my thread about it: https://www.digitalfaq.com/forum/vid...ping-luma.html

That was actually very helpful. Especially the link!

Sounds like, my Frame TBC is just doing its job but this is a side affect.

I've noticed the slither of red does grow tall or short which I think shows its trajectory.

I need to trust my eyes I think but it's daunting when some of these captures take hours and you don't know where the darkest or lightest scenes are going to be.