Using upper end Athlon Barton core or a P4 w/HT and hardware MPEG encoding on the capture device, how many capture devices can be running concurrently in one box? Anyone ever try this? Memory?

John

How many PCI slots do you have? Since the hardware MPEG cards are doing the working, CPU usage isn't an issue.

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cesman

When the source is open, the possibilities are endless!

I would like to use 5 or six cards.

Actually running 5 or 6 cards shouldn't be an issue, however hard drive limits could be. Make sure you've got a hard drive with a good transfer limit. Good luck

With one PVR-250 recording at the default resolution the HD light on my box goes flash-pause-flash-pause. There's definitely some extra disk bandwidth there, to figure out exactly how much however would probably require doing something like:

hdparm -Tt /dev/hda

and dividing that by the recording data rate of 1 card and some fudge factor to account for other overhead and writing rather than reading.

also don't know if anyone else saw it, but Sony has a box that has 7 tuners in it, so at least that many should be doable.

LOL I'm with the commenter I defy you to find 7 simulataneous shows worth recording. There are nights where I wish I had 3 tuners, but never more than that.

I currently have three tuners, three slot fans and an AGP video card in my master. The three tuner cards are all pvr-250s.

Since the three tuner cards are dumping mpeg2 data to the hard drives, hard drive read/write speed should not be a major issue. I may be wrong, but I have not seen a dvd drive (which also handles primarily mpeg2 data) with a higher value than dma2 on the market. a dma5 or dma6 hd should be able to sustain the bandwidth you seek.

This will not be the case with bt878 capture cards. Those will be dumping raw video at a much higher transfer volume.

The flip side is that the mpeg encoder chips on the pvr-[2|3]50 cards do get warm when recording. You may want to see how system tempretures are affected by adding video capture cards. If you don't like the tempreture after 4 or 5 cards, don't add any more.

The slot fans in my system can be pulled. but I am happier with them there at the moment.

If you have video on the motherboard, or don't intend to have a head on this box, (using it as a master with much lighter duty boxes elsewhere for actually viewing what you have been recording) I don't see any immediate problems with having seven (or as many as there are pci slots in whatever system you are working from) tuners in the box.

That brings up the other bottleneck however, which is drive capacity. I am sitting with about a 75% capacity on my 200G hd, using three tuners. Unless you plan on doing a raid array of 300G or larger drives, you are likely to run into storage capacity issues before you have any other issues. One hour of mpeg-2 video from a pvr-250 card eats up 2.2 to 2.3 Gig. Times 7 concurrent recordings, that's 15 gig per hour. If you load tested this by recording 7 channels over a 48 hour weekend, (perhaps multiple Stars, HBO, and Showtime channels all had something to watch) you would tie up 720 Gig of hard drive space. (Add in Friday night, it could easily go over a terrabyte.)

For my part, since I have three tuners in play, I have never run into a situation where I have a blocked recording. I won't say that's going to be the case for all people, but it does work out ok for me.

-Rusty

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Master:
- AMD 1800XP on a MSI KT4V motherboard, via KT400 bios
- 120 G Segate Baracuda /, /cache, /myth, swap
- 200 G Segate Baracuda /myth/tv
- 3 Haupauge! WinTV PVR250s
- 19" Daewoo Monitor (1280x1024 ni)