Histogram for Amarec TV

[Alwyn]

Hello all,

I'd like to use a histogram when capturing with AmarecTV. I have Graphstudio running to provide access to my Proc Amp on my GV-USB2 (thanks a million, Jagabo!) and would like to have a histogram.

I'd be grateful if somebody could advise me how to set this up.

Thanks!

[jagabo]

With many devices can build a capture graph in GraphStudio then open that graph with AviSynth's AviSource() or DirectShowSource(). Then you can use AviSynth's Histogram() function to get live feedback while you adjust the proc amp. The exact graph varies from device to device. Search through these forums look for examples. I've been playing with a US$6 HDMI capture device that emulates a webcam. Here's an example using that:


[Attachment 57964 - Click to enlarge]

In that image you can see the simple GraphEdit graph (most capture devices will need a more complex graph) that's used both for capturing and for adjusting the proc amp. The AVS script looks like:

DirectShowSource("cap.grf", audio=false, framecount=100000) 
BilinearResize(width/2, height/2) #  just make it smaller for this test
TurnRight().Histogram().TurnLeft() # horizontal waveform monitor at the top of the frame
ConvertToRGB(matrix="rec709") # the device is putting out rec.709

MPCHC is playing that AVS script. When the proc amp is adjusted you get near realtime feedback in MPCHC (just a small lag which will depend on the device you're using).

Here's a thread with some more complex graphs:

https://forum.videohelp.com/threads/399547-Closed-Caption-capture-using-specific-hardware

Those aren't for AviSynth monitoring but they may give you ideas about kind of filters you need to string together. Leave a video (and audio?) output pin open for AviSynth.

[Alwyn]

Thanks Jagabo, I'll check that thread out.

[Alwyn]

Jagabo, thanks a million (again); I finally overcame my AVISynth phobia and got this running:


[Attachment 65330 - Click to enlarge]

If I understand correctly (based on my Virtual Dub histogram experience), I'm trying to keep the top line as close to, but not in/above, the brown upper band, for Contrast. The brightness looks like it controls the small white dots/squares on both edges at the bottom of the histogram. I set the brightness first, then the contrast.

Do I have to look out for anything in relation to the lower, blue, line?

[Sharc]

When you scroll through the video the waveform of the active picture should fluctuate between the lower and upper brown bands, means luma (Y) between 16 (black, dark scenes) and 235 (white, bright scenes). The 16 ...235 range is sometimes called "TV range" or "limited range".
The full scale including the brown bands represent luma 0 ..... 255. The lower brown band represents luma 0 ...15 and the upper brown band represents luma 236 ... 255.

[Alwyn]

Thanks Sharc, I'm interested how Brightness and Contrast affect the AVISynth histogram.

I'm having a problem now; I can't have AmarecTV and MPC running at the same time. it seems they're fighting over the graph?

MPC running, then trying to open AmarecTV:


[Attachment 65333 - Click to enlarge]

And when AmarecTV is running, when trying to open the AVS in MPC:


[Attachment 65334 - Click to enlarge]

I'm sure that when I initially started this today, both would run together, but now, they won't, or was I confused and they won't ever run together?

[jagabo]

If I understand correctly (based on my Virtual Dub histogram experience), I'm trying to keep the top line as close to, but not in/above, the brown upper band, for Contrast. The brightness looks like it controls the small white dots/squares on both edges at the bottom of the histogram. I set the brightness first, then the contrast.

Do I have to look out for anything in relation to the lower, blue, line?

You want the brightest brights just at or below the upper brown bar, and the darkest darks just at or above the lower brown bar. Of course, not all shots will have full black and full white so find shots with especially dark and bright areas. Also, you don't really care about the black bars at the left and right edges (or at the top and bottom with letterboxed videos) as they aren't really part of the picture.

I never had problems with both a capture program and AviSynth using a graph with the proc amp controls at the same time. Try rebooting. sometimes a program gets stuck shutting down -- it's window is closed but the program is still running and the capture device is still in use. Another thing to try is to route all unused pins of the graph (aside from the video output) to the NULL renderer.

[Alwyn]

Thanks Jagabo. I'm struggling with the connected-pins concept in Graphstudio but will persevere.

[Alwyn]

Update.

Looking at this again, since the video is displayed in MPC when that script is opened (provided the VCR is running, of course), there is no real need to have AmarecTV running at the same time. You can set the levels with the MPC display/AVISynth histogram and then close it open AmarecTV and commence capturing with the same levels set. The only thing you can't do is use the histogram on the fly (that's if you can't run MPC and AmarecTV together).

To create the GRF file for the script, install and open Graphstudionext then:

On the Graph menu, click Insert Filter.

The left column shows the various video filters on your system. Scroll to locate the filter for your capture stick or card.

Click on the “Analogue Capture” line for your capture stick or card (either will do), then click Insert and close that box.

Right-click on the box for your capture device, then choose Properties

Open the “Video Proc Amp” tab and you’ll gain access to the procamp controls. You can now watch the video and adjust the brightness and contrast (and the others) in real time.

Save the Graphstudio setup using File>Save as Graph (GRF). You can then use that GRF file to quickly re-open the graph next time.

[Alwyn]

Lastly, I'm not sure what component of AVISynth is needed to run that script; my brain is a complete fuddle with this and my system has so much AVISynth stuff all over it (trying to get QTGMC to urn) I can't remember whether only the basic AVISynth install is necessary or whether more components are required.

[Sharc]

Lastly, I'm not sure what component of AVISynth is needed to run that script; my brain is a complete fuddle with this and my system has so much AVISynth stuff all over it (trying to get QTGMC to urn) I can't remember whether only the basic AVISynth install is necessary or whether more components are required.

I would assume that a basic and standard Avisynth installation will do as the histogram() is part of the basic installation.
A little warning though: From the past I remember that the Proc-Amp settings got reset to their defaults whenever AmarecTV was restarted, or even after pressing the Record button in AmarecTV, and I had to re-adjust the sliders immediately to the positions which I knew from earlier calibrations. So I would strongly suggest to keep an eye on the sliders. Maybe that was an oddity of my system only or the particual Windows version of that time.

(In practice, all I had to do to keep the waveform in the 16....235 range is to reduce the contrast a few notches for my USB-live2. For the GV-USB2 the default settings were just fine. The driver of the GV-USB2 makes a contrast reduction by default and also reduces sharpness, preventig halos. All the fine tuning in post processing anyway.)

[Alwyn]

Sharc, thanks for the info on AVISynth components.

I remember that the Proc-Amp settings got reset to their defaults whenever AmarecTV was restarted

Depends on the device, Sharc. The Live2 dumps the settings when you close Graphstudio or AmarecTV. The GV-USB2 retains the settings in both cases.

In practice, all I had to do to keep the waveform in the 16....235 range is to reduce the contrast a few notches for my USB-live2.

That is the whole point of this (and the other Dark Capture) topic. Get it basically right before capture by adjusting the proc amp, then tweak in post.

[Sharc]

I remember that the Proc-Amp settings got reset to their defaults whenever AmarecTV was restarted

Depends on the device, Sharc. The Live2 dumps the settings when you close Graphstudio or AmarecTV. The GV-USB2 retains the settings in both cases.

Apparently yes. I just verified that the GV-USB2 retains the settings, while USB-live2 does not . Thanks for pointing this out.

[Alwyn]

After feeling chuffed that I'd got a easy alternative to viewing the histogram, I've struck a problem. My GV-USB 2 and USB Live2 will not open in MPC-BE. My Startech USB3HDCAP has no such problem and will open in MPC-BE and display the histogram nicely.

I've tried a couple of versions of MPC and Graphstudio to no avail. I've done a reboot. I have chosen "connected" on the graphstudio item for each. I can access the Proc amps through Graphstudio's "properties" and both cards open normally in AmarecTV and VDub for capturing. The GRF file can be opened in Graphstudio to display the item.

Details are as follows:

Error message:


[Attachment 70703 - Click to enlarge]

AVISynth script:

DirectShowSource("GVUSB2 Graph.grf", audio=false, framecount=100000) 
BilinearResize(width/2, height/2) #  just make it smaller for this test
TurnRight().Histogram().TurnLeft() # horizontal waveform monitor at the top of the frame
ConvertToRGB(matrix="rec709") # the device is putting out rec.709

The Startech script is exactly the same apart from the naming of the file in line 1.

Any ideas will be welcomed.

[Sharc]

@Alwyn: I had a similar experience here with the live2 and the GV-USB2. As a pragmatic solution I did some test captures with selected scenes with dark and bright content, then inspecting the result with the waveform monitor and if necessary re-adjust the proc-amp sliders to stay "reasonably well" within the 16....235 luma range (most important: no clipping), and kept this as my standard settings. The rest in post. That's for AmarecTV. (I dropped Vdub and its histogram for VHS capturing btw.)
Re-visit this calibration when changing devices and drivers of course.

[Alwyn]

Thanks Sharc, that's disappointing but thanks for the feedback. Good to know I wasn't messing it up due to incompetence. I have been using VDub's histogram so I'll continue to do so unless I'm using the Startech.