Virgin Media Cable TV and MythTV
AV Capture from Scientific Atlanta/Cisco 4200DVB
Until my 4200DVB's PSU died, I was able to successfully capture video data from the "VCR" SCART socket (via a ProfiGold SCART-to-RCA/S-video adaptor, switch set to "output") into my Hauppauge HVR-4000 card. Video was output from the adaptor's composite RCA output (yellow), and taken via a composite video lead and the Hauppauge-supplied RCA-to-7-pin mini-DIN S-video lead to the HVR-4000 composite/S-video input. Stereo audio was output on the red/white RCA outputs of the adaptor and input into my mobo's "Line In" jack via a 2xRCA-to-stereo jack cable.
With the SCART adaptor plugged into the STB's "VCR" SCART socket, it's S-video output, when captured by the HVR-4000, gave a black-and-white picture with a shifting, Moire-like interference. This was thought to be due to the SCART socket (and thus the S-video output of the adaptor) either:
a) outputting only luminance (Y) data (doesn't explain the interference, though)
b) outputting composite video on the Y channel
This latter case would explain the black-and-white picture seen, the additional chroma (C) data present in the composite signal being interpreted as interference to the luma signal.
Case a) is supported by reports of SCART "down" sockets (of which the STB's "VCR" socket is probably an example) rarely implementing the "S-Video C down" function on Pin 7, whilst case b) is supported by the fact that the VirginMedia STB software did not give the user the choice of S-video as a SCART output format, probably meaning that the shared Pin 19 would always output composite video.
Unfortunately, I wasn't able to progress the capture of S-video data from the 4200DVB before it passed away. All I can say is that capture of composite video worked OK.
AV Capture from V HD Box (Cisco 4585DVB)
TrustedReviews.com review of V HD Box (Cisco 4585DVB) inc. photo of back panel connections