Why is my StarTech capture so funky?

[JVRaines]

I just got a StarTech SVID2USB2 and tried it out with a VHS tape of SMPTE bars. Here's how the bars scope in a DV capture from my Canopus ADVC110:



Pretty close to hitting the marks. And here is the same tape in an uncompressed YUY2 capture from the SVID2USB2:



The chroma is kind of miserable. Could I be doing something wrong in VirtualDub? Should I suspect a bad dongle?

[pippas]

I use both a Canopus ADVC50 (same Canopus DV chipset as ADVC110) and an EZCap 116 (same chipset as the Startech (Empia 2860/1 - Silan SC8113 ))

I find I get my best results from the EZcap device using an intermediate codec rather than uncompressed (fewer dropped/ duplicate fames).
I currently use Grass Valley HQX as the intermediate

I made a clip of EBU 75% colour bars as an HD file, which I then loaded into my WD Live player. I connected the composite output from that, to my old Panasonic DMR E55 (which I use for frame sync with VHS sources)

The S-video output from The Panasonic is connected to either the Canopus ADVC50 or Ezcap 116 Svideo in.

So an identical reasonably good quality source input to allow for a comparison.

I opened the raw files as captured and using the Avisynth VideoScope plugin, got the following results:



DV Capture




EZCap Capture

The EZ file is closer in levels to the original than the DV file - I have yet to check out why that is ...

I don't think the EzCap file is as good as the DV file, but I have to say that in general use the EZCap performs better than I expected, using the HQX codec.
(Previously I have only seen Mpeg2 captures made with the software supplied with the EzCap device - which were not so good!)

There is still the hassle of not having locked audio of course - and the USB audio capture is not good on my EZCap. (Sound card input is much better quality)...
But when you consider the extra cost of a Canopus converter - and the need for Firewire, which can be a problem with Laptops for example - then the Empia 28xx based devices - like the StarTech, Grabbee, EzCap etc, etc .. look like a useful alternative for analogue capture.

Looks like there's usually a bit of messing around to get the best from them though....

[jagabo]

I think it's a rec.601 vs rec.709 problem. Try:

ColorMatrix(mode="rec.601->rec.709")

Some saturation adjustments may be needed before or after the colormatrix conversion.

Maybe a YIQ vs YUV issue? Try this:

Tweak(hue=33)
ColorYUV(cont_u=50)
Tweak(hue=-33)

[pippas]

Thanks for those suggestions Jagabo. By adding the lines :

ConvertToYUY2
ColorMatrix(mode="rec.601->rec.709")
Levels(16, 1, 235, 0, 255, coring=false)

to the DV file script, the DV file levels are now pretty much an exact copy of the original. Thanks for that.

Am I right in thinking that The EZCap levels will depend more on the Vdub capture proc amp settings?.......

I'm not quite sure how best to adjust them....At present they're set at the default values, with the exception of the Brightness which is set to 122.
That was the value which seemed to be the minimum value for the white to remain at 255, as per the EBU colorbars.

I'm also not sure if my being in PAL land makes any difference to how to approach any corrections?
(We seem to have generally avoided having to use 'hue' over the years! )

But the other EZcap levels are not as accurate as the DV levels, which are now nearly perfect, following your rec.601->rec.709 suggestion.

[JVRaines]

Well, if there is no input to my actual OP, I'm just going to send this cheap StarTech converter back. I can afford to spend more, though I don't have the budget for anything like a KONA card.

[jagabo]

Well, if there is no input to my actual OP...

My post was directed at you. Can you provide samples of your two caps?

[pippas]

Well, if there is no input to my actual OP, I'm just going to send this cheap StarTech converter back. .

Sorry, I thought that my post might help by showing what a similar device does with a better source (i.e. not a VHS genreated colorbar)

I thought it might give you an idea of what you might expect from such a device .. sorry you didn't find it useful.

The Startech is just another Empia 2860 device (although the price seems to be little higher than most?..) . They're OK for what they do.
Not perhaps as 'clean' as the Canopus, but a lot cheaper. There are also no DV artifacts either of course.

But capturing VHS depends on so many other factors than just the capture device.....

[JVRaines]

Well, if there is no input to my actual OP...

My post was directed at you. Can you provide samples of your two caps?

Sorry, I didn't realize that. Okay, using ColorMatrix 601->709 on the YUY2 file gives a much better result. But why? This is an SD converter. Shouldn't it be doing the job in Rec. 601 space?

[pippas]

I think it's a rec.601 vs rec.709 problem.

Well my problem was that as well...

Adding the colormatrix code to the script give much better color results:



DV (Canopus ADVC)


EZCap (Empia 2860 device)

Thanks for your help Jagabo...

Sorry to the OP for the 'hijack' ... it wasn't intentional

[JVRaines]

Sorry, I thought that my post might help by showing what a similar device does with a better source (i.e. not a VHS genreated colorbar)

Didn't mean to be snippy, pippas. Thanks for the information. This is a baseline comparison of two converters with a real SVHS source and no preprocessing. I'm hoping to get uncompressed captures that are better than my DV converter without filtering conversions.

[jagabo]

using ColorMatrix 601->709 on the YUY2 file gives a much better result. But why?

It makes no sense. A driver or firmware problem? And increasing the saturation a bit will get it nearly perfect.

Well my problem was that as well...

Adding the colormatrix code to the script give much better color results:

Using the two images in your first post, assuming the JPG images were made with a rec.601 matrix, I found this makes the DV cap match the other very closely:

ColorYUV(gain_y=20, cont_u=13, cont_v=15, off_v=-1, opt="coring")

Of course, the other isn't very close to correct. Adding the colormatrix adjustment makes them both closer the standard.

[Brad]

Are you sure the program generating the scopes interprets SD YUY2 correctly?

As for pippas' results, HD colorbars played on a WD TV Live to composite...

[jagabo]

Are you sure the program generating the scopes interprets SD YUY2 correctly?

That seems the most likely explanation. Try using VideoScope() in AviSynth. Here's a reference using ColorBars() and VideoScope():

ColorBars(pixel_type="YUY2").Crop(0,0,-0,240)
#AddGrain(var=1.0, uvar=1.0) use this to make the dots more visible
VideoScope("both", true, "U", "V", "UV")
ovr=ImageSource("vectorscope overlay.png") # SD rec.601 color bars
Overlay(last, ovr, x=width-256, y=height-256, mask=ovr)

Remove the last two lines if you don't want the overlay that marks the standard locations on the vector scope. "vectorscope overlay.png" attached.

[JVRaines]

Are you sure the program generating the scopes interprets SD YUY2 correctly?

Ah, that's precisely it. It seems my Windows system assumes that an uncompressed AVI is BT.709. When I save in the Lagarith codec, the file is properly interpreted as BT.601.

Now my problem is the audio hardware in the SVID2USB2. The input is too sensitive and easily clips on typical -10 dBV levels. I have to run the audio through a mixer to bring it under clipping.

[Brad]

No guarantees, but you can try finding the relevant registry keys, adding these DWORD entries, and tweaking them to adjust the volume. From the driver's INF:

; AC97 source balance adjustments - valid range 0..127
;;;HKR,settings\OEMSettings,AC97VolumeTV,0x00010001,64  ;
;;;HKR,settings\OEMSettings,AC97VolumeFM,0x00010001,64  ;
;;;HKR,settings\OEMSettings,AC97VolumeLN,0x00010001,64  ; Line IN

...

HKR,settings\PropDefaults,Volume,0x00010001,0           ;

AC97VolumeLN works for the ATI 600. The other settings probably won't do anything. All of the AC97 values are commented out in the INF, so they won't be present until you add them.

[JVRaines]

Thanks for the wizardly advice! I will try it out and report back.

[VHSRules]

I just got a StarTech SVID2USB2 and tried it out with a VHS tape of SMPTE bars. Here's how the bars scope in a DV capture from my Canopus ADVC110:


[Attachment 35906 - Click to enlarge]

Pretty close to hitting the marks. And here is the same tape in an uncompressed YUY2 capture from the SVID2USB2:


[Attachment 35907 - Click to enlarge]

The chroma is kind of miserable. Could I be doing something wrong in VirtualDub? Should I suspect a bad dongle?

Very interesting images, is that some sort of scope you are using to analyse the bars? And how do you generate the bars? Im fairly new to this stuff, and keen to improve my knowledge.

[JVRaines]

No guarantees, but you can try finding the relevant registry keys, adding these DWORD entries, and tweaking them to adjust the volume. From the driver's INF:

Thanks again for the hack. I reduced AC97VolumeLN to 32 and no more clipping. I wonder how many users are getting crappy audio with this thing out of the box? Then again, I've met pros who fixate on the video and let audio mistakes slide.

Very interesting images, is that some sort of scope you are using to analyse the bars? And how do you generate the bars? Im fairly new to this stuff, and keen to improve my knowledge.

They're the scopes built into Sony Vegas. They mimic the vectorscope and waveform monitors used for decades by video engineers. I recorded tone and bars to SVHS tape with a Canopus ADVC110 bidirectional converter.

[VHSRules]

No guarantees, but you can try finding the relevant registry keys, adding these DWORD entries, and tweaking them to adjust the volume. From the driver's INF:

Thanks again for the hack. I reduced AC97VolumeLN to 32 and no more clipping. I wonder how many users are getting crappy audio with this thing out of the box? Then again, I've met pros who fixate on the video and let audio mistakes slide.

Very interesting images, is that some sort of scope you are using to analyse the bars? And how do you generate the bars? Im fairly new to this stuff, and keen to improve my knowledge.

They're the scopes built into Sony Vegas. They mimic the vectorscope and waveform monitors used for decades by video engineers. I recorded tone and bars to SVHS tape with a Canopus ADVC110 bidirectional converter.

Ah thats very interesting. You are comparing the Tone & Bars capture from two different capture devices. I like this kind of objective test. I suppose the more the signal moves away from the reference lines, the worse it is.

[JVRaines]

Ah thats very interesting. You are comparing the Tone & Bars capture from two different capture devices. I like this kind of objective test. I suppose the more the signal moves away from the reference lines, the worse it is.

I made the tape to line up some outboard equipment — a dedicated processing amplifier and a frame synchronizer with built-in proc amp. Of course, the tapes that I ingest for conversion have levels all over the place, but I want to ensure that my chain is neutral before I start making adjustments.

The markings on the scopes are indeed targets for a SMPTE test pattern. In this case, Vegas was fooled by Windows components (DirectShow?) that guessed the wrong color space for an uncompressed AVI file. When I used a lossless codec instead (Lagarith), the colors were interpreted correctly.

[mnewxcv]

No guarantees, but you can try finding the relevant registry keys, adding these DWORD entries, and tweaking them to adjust the volume. From the driver's INF:

; AC97 source balance adjustments - valid range 0..127
;;;HKR,settings\OEMSettings,AC97VolumeTV,0x00010001,64  ;
;;;HKR,settings\OEMSettings,AC97VolumeFM,0x00010001,64  ;
;;;HKR,settings\OEMSettings,AC97VolumeLN,0x00010001,64  ; Line IN

...

HKR,settings\PropDefaults,Volume,0x00010001,0           ;

AC97VolumeLN works for the ATI 600. The other settings probably won't do anything. All of the AC97 values are commented out in the INF, so they won't be present until you add them.

sorry but could you explain how to add these entries? I need this desperately

[Brad]

1. Start menu -> Run -> Type regedit.
2. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Class\{4D36E96C-E325-11CE-BFC1-08002BE10318}. There are a bunch of keys under Class with similar-looking strings of characters. The first block of the one that you want ends in "C". To double-check you're at the right spot, click on this key (it looks like a folder) and you should see the (Default) value as Sound, video and game controllers in the right-hand pane.
3. Under this key are a bunch of numbered subkeys. Expand any that have their own subkeys. You're looking for one that contains settings\OEMSettings. Hopefully you only have one of these entries, as narrowing down individual device installations is a bit more complicated.
4. Having located the correct device and navigated to OEMSettings, right-click on the right-hand pane and choose New -> DWORD (32-bit) Value.
5. Name it AC97VolumeLN.
6. Double-click it and experiment with different numbers. JVRaines said he set it to 32, but I don't know whether that was hexadecimal or decimal.

[mnewxcv]

[Attachment 37777 - Click to enlarge]

1. Start menu -> Run -> Type regedit.
2. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Class\{4D36E96C-E325-11CE-BFC1-08002BE10318}. There are a bunch of keys under Class with similar-looking strings of characters. The first block of the one that you want ends in "C". To double-check you're at the right spot, click on this key (it looks like a folder) and you should see the (Default) value as Sound, video and game controllers in the right-hand pane.
3. Under this key are a bunch of numbered subkeys. Expand any that have their own subkeys. You're looking for one that contains settings\OEMSettings. Hopefully you only have one of these entries, as narrowing down individual device installations is a bit more complicated.
4. Having located the correct device and navigated to OEMSettings, right-click on the right-hand pane and choose New -> DWORD (32-bit) Value.
5. Name it AC97VolumeLN.
6. Double-click it and experiment with different numbers. JVRaines said he set it to 32, but I don't know whether that was hexadecimal or decimal.

worked like a charm. I set it to 127 hexagonal and it dropped my extra loud tape into the normal range. 50 seems to be the sweet spot for my home movies, though they were not clipping to begin with, it moves their peaks to between -10 and -6. Thanks a lot, I needed this!

[JVRaines]

Worked like a charm. I set it to 127 hexagonal and it dropped my extra loud tape into the normal range.

I thought the polygonal registry was still in beta!

[mnewxcv]

Worked like a charm. I set it to 127 hexagonal and it dropped my extra loud tape into the normal range.

I thought the polygonal registry was still in beta!

lmao! hexaDECIMAL