I am a bit disappointed with DScaler's decoding quality though, at least at the default settings.
The hardware decoding quality is nothing special, but the real advantage of this card is that we can capture raw sample data before it's decoded, and then perform high-quality decoding in software. I've uploaded my programs for doing this to http://www.reenigne.org/misc/vbicap.zip . First make sure DScaler is closed, then run vbicap.exe from the archive. This will open a connection to the card (via DScaler's dsdrv4 driver) and stay running. Next try running capture_field.exe. This should generate two files in the current directory - captured.png (a 640x480 capture decoded with my algorithms) and captured.png.raw which is 460800 samples (approximately one field) of composite data sampled at ~28.6MHz (approximately 8 samples per colour carrier cycle). Easiest way to examine this is to open it up in an image editor that can open raw data files (in the "binary data" sense, not the "camera raw" sense). I use Paint Shop Pro 4 for this. Set it to no header, single greyscale channel (8 bits per pixel) with dimensions 1824x252. If your card is like mine there is will be a slight leftwards slope as you go down the image due to the card's sample rate being slightly slow. About 10 scanlines worth of picture will be missing from the bottom of the image (I haven't figured out how to get the card to do gapless captures or if it's even possible with this hardware).
If it complains about a missing msvcr110.dll you can install that from https://www.microsoft.com/en-gb/download/deta … s.aspx?id=30679 . Any other missing dependencies let me know.
When you're done capturing, run vbicap_close.exe to close vbicap.exe (closing it directly may cause the card to DMA over random bits of RAM and make your machine unstable).
In any case, I am anxiously awaiting your test programs.
I will work on the Tandy versions of the test image and calibration program tomorrow.