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The question suffers from a lack of definition. What source of video is being used (CATV|DirectTV|Broadcast Satelite Feed)? What quality are we looking for (D1|DV|320x240)? How much programming is being recorded (24/7 per channel|Selected scheduled programs)? What is the destination for the recorded media (Direct View|Streaming|DVD Archive|MPEG-4 Sharing)?

The solutions would result from the answers to these questions. Sony makes an excellent line of MPEG video servers for broadcast environments. It costs big bucks, but you can put together a video capture/agregation/distribution setup worthy of a DBS broadcaster that way. That's the high road.

Middle of the road, and for the poorer video sources (DirectTV and CATV) would probably be best served by a half-rack of 1U systems with MPEG-2 or -4 capture cards. I would avoid using 4 cards per system becaue the cost/density/stability equation doesn't work. Why get raid or extra hdd controllers to make a system work when you can have a nice stable single-stream system? And no worries about PCI bandwidth/latency/conficts. Depending on output format you can have the systems encode directly or share to a separate encoder / dvd mastering system. Also, consider using professional pre-filtering hardware to reduce noise and improve video quality before the capture/encoding phase in order to reduce the load on general purpose processors that have trouble handling the full datarates of video in real time.

If your goal is just to get it done and do it cheap (and your goal isn't 24/7 or real-time streaming) I would suggest that a stack of DirectTivos would be the best bet. At $500 for 2 simultaneous recordings, I doubt you'll beat the price point, stability, and program guide availability, and using a control box and some scripting with available TivoWeb and mpeg offloading utilities, you'll get good results without having to do all the engineering yourself.

That's just a couple of ways to do it. Probably as many routes as there are users of such systems. And we haven't even scratched the thorny stuff like de-interlacing, multi-system (PAL/SECAM), HDTV and HDCP!

No, for complex reasons:How many frames can humans see?

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