Any idea how much bandwidth the Brooktree cards take? I wasn't aware the BT quality is lower, although that might be okay because i'm not actually seeking them for primary use but more for overflow use. Would anyone have screengrabs or examples of the quality difference?If you spewing uncompressed digital video, it takes a lot of bandwidth. The "lower quality" that I refer to is the poor Y/C separation of the chip for composite video. It uses a simple chroma notch out of the luma, which removes most luma bandwidth above 3MHz. With a comb filter (or using the S-vid input), this notch can be disabled and full luma bandwidth can be recovered.
Sounds like an OK plan. I never figured out the priority stuff correctly, though, when I had a single PVR-250 card and a bt878 overflow. I was quite pissed when a "good" recording was recorded on the "not-so-good" card. This was a few versions of mythtv back, though. I think that can be better specified now. I just got another PVR-250... much happier.
My hope is to primarily use the BT cards as 'overflow' and informational programming. When something good is on like Star Trek i'm hoping to rip it to a Hauppage. For more informational things like History Channel VCR quality and perhaps mono may be okay,
I may also use lower
resolutions (352x288 maybe) to reduce CPU and hard drive requirements. (hoping a 2.8-3.0Ghz P4 would be enough to record 3 lower res dumb card streams into divx)That's a possibility, but I highly recommend keeping all 480 lines in the capture. Doing vertical scaling on a video signal is a weird thing and will undoubtably introduce lots of strange interlacing artifacts. My experience has been that even capturing at 160x480 is not too objectionable. A VCR on EP has the equivalent of about 240x480... and that's perfectly viewable. Much moreso than 320x240 IMO. Don't get hung up on such a stretched capture.... it makes a lot of sense from a video standpoint. H signal much higher frequency than V, so cutting H first makes sense.
I got a second one so I never had to worry about scheduling conflicts. I don't record much, but sure as hell once in awhile there are two things on at the same time you want.
Getting 3 cards working is more of a desire to experiment and out of curiosity than intending to remain like that as a long running PVR. Just to see if it's doable even if it requires lower res. I want at least one and preferably two working with a couple of Hauppages if possible.
Where can I find information on the 'hack' to enable 4x faster sampling in a BT878 card?? That sounds cool. :) There's not much info on the gnuradio site, and one important link is dead.
It appears to be down now, but this is where I saw it: www.domenech.org/bt878a-adc/index-e.htm You can get a google cache of it: http://64.233.161.104/search?q=cache:Ej6uUv5s388J:www.domenech.org/bt878a-adc/index-e.htm+bt878a-adc&hl=en
-Cory ************************************************************************* * Cory Papenfuss * * Electrical Engineering candidate Ph.D. graduate student * * Virginia Polytechnic Institute and State University * *************************************************************************
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