OK, I will have to buy a 2gb micro SD card & adapter so I can upgrade the FW and save the settings.
My TV does not seem to alter the image if I cycle the inputs on the TV, but I played around with the OSSC some more while using the DTV 480P input setting instead of “auto”/”VESA”.
480p Advanced Timing defaults & changes:
H Samplerate 858 (default) to 910
H Synclen 62 (default)
H Active 720 (default)
VActive 480 (default)
H Backporch 60 (default) to 100
V backporch 30 (Default) to 33
Adjusting the H Samplerate and the H backporch centered and stretched the image out to where the few vertical pixel columns on either side of the screen that the Dreamcast fades just a little are overscanned and are beyond the edge of my screen.
I adjusted the vertical backporch to raise the very bottom of the “shenmue clock” above the bottom edge of the screen.
I seemed to notice that adjusting these settings while using the DTV standard seems to re-size things on screen to maintain the aspect ratio, so the “shenmue clock” or shenmues on-screen buttons get larger all around, whereas stretching/re-centering the image though the Advanced Timing settings while using the VESA 640×480 input setting stretches the image horizontally a little.