There's been a bit of discussion about the various USB capture cards/sticks concerning the chips inside; elcrappos, Conexants etc.
How do I find out what's in my GV-USB2?
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Should be a Grass Valley chip (old Canopus)
BTW, can you tell me in what range the card captures by default (0-255, 16-255, 16-235)?
Edit: added question
Originally Posted by Davexnet
Originally Posted by Lollo
I'm comfortable with VDub's. This is with the Brightness at 128 and the contrast wound all the way up to 255 (that's not what I'd use for capturing, obviously). Are the cropped end bits indicating it's 16-235, and is that a bad thing?
[Attachment 58205 - Click to enlarge]
Last edited by Alwyn; 2nd Apr 2021 at 07:28.
Checked that out but couldn't see anything that identified the internals.
The AviSynt histograms are used to check levels after capture (Sometimes I use them also in parallel with AmarecTV, but that's another story)
If I understand correctly your picture, you are clipping darks < 16 and whites > 235. If possible you should avoid that, but sometimes the proc amp fails to correct levels because the clipping arrives early. You have to experiment a lot by yourself!
Thanks Lollo, yes, I am using the Brightness and Contrast to stay within the 16/235 edges.
I'll dig further for the chip details.
It looks like it uses a Renesas (formerly made by Techwell) TW9910 10 bit video decoder chip, Cirrus Logic CS5340 24-bit/196khz audio decoder chip and a Syntek stk1150 USB bridge judging by this disassembly. Not aware of any other capture devices that uses any of the Renesas/Techwell chips. From the threads on e.g here and dfaq it these dongles seem to be pretty decent. Some easycap cards use a similar STK1160 bridge chip, but different video (seems to be often a SAA7113H-compatible knockoff chip, but some apparently have a genuine one too.) and audio chips. The audio chip in the io-data seems to be more fancy than the ones used in other dongles.
Histogram gaps can be an indication of the video levels being digitally scaled in a very simple manner. On some other cards you get this sawtooth-like pattern on the virtual histogram depending on the level setting.
oln, terrific, thank you.
It looks like it uses a Renesas...
Histogram gaps can be an indication of the video levels being digitally scaled in a very simple manner.
On some other cards you get this sawtooth-like pattern on the virtual histogram depending on the level setting.
[Attachment 58208 - Click to enlarge]
Yeah I get the same thing with the Diamond VC500 which uses similar hardware to the hauppauge. there are some proc amp settings where it's less and some more. It's even more noticeable on the histograms the empia-based VC500MAC card I got, for those I know the empia chip has separate level settings which probably just adjust stuff digitally (and would be 8-bit luma 4:2:2) rather than adjusting input gain on the video chip itself.
BTW, can you tell me in what range the card captures by default (0-255, 16-255, 16-235)?
With the Hauppauge USB-Live2 I have sawtooth-like pattern on the histogram even if I do not touch the proc amp (default).
Are there settings in the capture device driver, that can be changed?
I do not know what is implemeted in the different driver versions, but the Hauppauge captures 16-254. You should use its proc amp setting to have your deepest black at 16 (sort of shrinking the default histogram to stay in 16-254 range). Doing that you may increase or not the sawtooth pattern, according to my and oln's experence.
BTW, imho Hauppauge USB-610 does not have too much contrast, your video requires adjustement to be properly captured with this card.
The whites are not clipped by the Hauppauge (it captures 16-254), I think they are too high in your video, and maybe need tuning as well.
Do you get this toothy histogram in live-action images, as well?
Just a guess, but the toothy histogram may be the result of data compression used by the cable/satellite company.
I haven't had a chance to play much with the proc amp yet. Right now, it's just guesswork for setting levels. It would be nice if I had a color-bar source, for calibration---rather than having to guess. Does the proc amp in VDub or AmarecTV work directly with the A/D driver of the Hauppauge?
toothy histogram may be the result of data compression used by the cable/satellite company.
It would be nice if I had a color-bar source, for calibration
Try for example
[Attachment 58217 - Click to enlarge]
A basic command changing the pattern is ConvertToRGB(interlaced=false, matrix="PC.601").ConvertToYV16(interlaced=false); matrix="PC.601" must be in one of the 2 conversion, but not in both.
[Attachment 58215 - Click to enlarge]
As I said, a simple GamMatch() or a complete script including denoising and sharpening remove the pattern.
[Attachment 58216 - Click to enlarge]
Last edited by lollo; 3rd Apr 2021 at 03:06.
I was going to suggest denoising (or a slight blur) plus sharpening, to clean-up your histogram. But, you beat me to it. I have often done the same thing to improve the quality of still images. Your modified image definitely looks better. Which, has me wondering if signal noise may have been the cause of your toothy histogram.
The reason that I wonder about the driver settings of the Hauppauge, is that I can capture the same video with an old Dazzle, without the contrast problem. There should not be that much difference in the captured images.
Even adjusting the proc amp, the Hauppauge blacks still appear to be clipped. Here is an image showing two captures of the same video---Hauppauge top, with proc amp adjustment, and Dazzle bottom, with no adjustment. Notice the histograms in the black, and the muddy discoloration of the dark areas with the Hauppauge. Also notice the bad interlacing of the Hauppauge, compared to the smoother results of the Dazzle:
[Attachment 58224 - Click to enlarge]
The Hauppauge is supposedly a better unit. So, I do not understand this, unless I am using the wrong driver settings. Or,could it be that the Hauppauge just doesn't like NTSC?
Last edited by anachronon; 3rd Apr 2021 at 12:28.
Which, has me wondering if signal noise may have been the cause of your toothy histogram.
Even adjusting the proc amp, the Hauppauge blacks still appear to be clipped.
The very dark parts of the histogram are the horizontal sync signal -- that's not a part of the active picture. Histograms are useless for this type of test. What you really want is a waveform monitor:
[Attachment 58235 - Click to enlarge]
This is more like what you want it to look like:
[Attachment 58236 - Click to enlarge]
jagabo said everything.
just a small addition for us beginners if you will work with the histograms:
- cut the non active part of the video with crop()
- check different options (Histogram("levels"), TurnRight().Histogram().TurnLeft(), VideoScope("both", true, "Y", "Y", "Y"), colorYUV(analyze=true); all says something
- your capture is now clipped at y=50! you should move the minimum to y=16 with proc amp settings. Jagabo processing is a post capture stretch to show you how it should be.
[Attachment 58237 - Click to enlarge]
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Well, the procamp in VDub has only "Levels" settings---brightness, contrast, etc... I am having to guess, as there is no histogram function during capture. I have to capture, view result, capture again, view again... Or, am I looking in the wrong place? This is really frustrating. Plus, it seems that I am only adjusting the levels after they have been digitized.
Can anyone suggest good levels or other settings to use with the Hauppauge USB-610? What about a good video source that I can use for calibration? I can't keep running my old tapes over and over.
Plus, I just ran into another problem. I finally found the right histogram function for use with capture. But now, the changes in levels that I make, don't apply when I start capture. They capture runs at the default settings. I am pulling my hair out!
Last edited by anachronon; 4th Apr 2021 at 21:48.
If you use VirtualDub
VirtualVCR instead of VDub). I can set the procAmp values and the preview reflects the changes, but when I want to save or start the capture the procAmp settings return to their defaults. Maybe one would have to tweak the registry, or to try with graphstudio to tweak and save the settings.
It's however not a huge problem here because as long as the captured waveform is not getting clipped one can make the adjustments in avisynth (tweak(), levels() ....) afterwards when encoding for the final format.
Edit: Setting the ProcAmp values via graphstudio didn't help. Settings can be changed but are immediately reset(?) to defaults or are at least not effective when starting the capture. Too bad.
Last edited by Sharc; 5th Apr 2021 at 08:06.
The GraphStudio technique usually works -- and the settings are remembered the next time you start using the capture device. But some drivers do reset the proc amp settings when you start a new cap (or after rebooting). You may still be able to use GraphStudio to set the proc amp immediately after you start capturing (the capture program and GraphStudio can both run at the same time).
It's even possible to use GraphStudio and AviSynth to get realtime feedback on the adjustments. You just build a capture graph with GraphStudio, then open that graph with AviSynth. I posted about this recently:
What you want to do is get a good compromise setting that will work across different shots on the tape, being sure that darks and brights aren't being clipped (ignoring the sync pulse and front/back porch -- the black vertical bars at the left and right edges which aren't part of the active picture).