DVR Project – The Computer

There are a few critical elements to the computer I was seeking, it had to be fairly recent (2Ghz+/- processor speed), it needed a few Gig of memory (either present or at least capable of increase) and the storage needed to be fairly large (IDE 500Gig HD minimum).

The computer also needed to be capable of working with the Ebay 8 channel DVR card (sadly something I never know until it comes time to plug the damn thing in) and finally the computer needed to be inexpensive.

I may have acquired that computer yesterday. An HP Compaq Desktop, 2.8Ghz processor, 500Meg RAM (one slot used and one remaining open, SDRAM) and 40 Gig HD, along with onboard sound, NIC etc etc etc for $89.99 – A clean $100 after the gummint took their due).

New DVR Computer?

The only problem with the PC appears to be the HP specific half height PCI slots, but thankfully the DVR card is half height, and it was a moments work with tin snips to get the card to fit with the case closed. Some quick exploring in Ubuntu and I confirmed that at least it was seeing 8 video devices (a good start), although all kinds of hardware detection errors kept threatening to rain on my parade.

In the end the card works fine. Up and running within a few hours. Higher resolution and frame rates chewed through 50% of the 40Gig drive in about 3 hours of experimentation (that was just one camera 640×480 at 25fps), upgrades are going to be imperative.

More experimentation with different distributions of Linux to see how much I can decrease the overhead without making the thing any more unfriendly than absolutely required.

Update: Satisfied that the DVR card works, I’m proceeding with upgrading both memory and storage, this requires some bargain shopping for DDR Ram and a 500Gig IDE drive so may take a bit of time. The good news is that experimentation with Linux doesn’t have to wait for the upgrades.


  1. Ted Onyszczak says:

    What compression does it record to MPEG, DV, H264? These things all make a difference and in Linux it can be hard optimizing CODECS, as it’s a little less plug-and-play.

  2. Ted Onyszczak says:

    PS, NTSC standard is 29.97 FPS if you ever plan to off-load, say to DVD. Don’t get me started about why 29.97 and not 30, it’s a herculean cluster fuck.

  3. Erik says:

    Actually I’m pretty sure it records each frame as a JPEG and then binds them together as needed, using (at least in the machine I have running) cambozola (A java viewer to stream them).

    There are also some optimization steps that I have yet to familiarize myself with, but the gist of it is that compression out of the box is hardly optimal (some tweaking required).

  4. Ted Onyszczak says:

    That would be m-jpeg, or motion j-peg, an older standard. I used to use it 7-8 years ago. The difference between that and say DVD is that MPEG keyframes, every 5 frames or so, to save size, whereas each m-jpeg frame is self contained, therefore uses more space. But Less, than DV. Are you planning to keep it 640X480? I used to go 320X240 and it still looked pretty good even projected on the huge screen in our mixing room. Better than VHS anyway.

  5. Erik says:

    I’m still doing some reading on how they’ve dealt with issues since I installed my current system, looks like I have some playing around to do.

    Resolution? A variety actually. A few cameras recorded at 640×480, the majority at 388×260 (or some mutant slightly larger 320×240 res), variable frame rates to reduce processor load (typically 5fps, kicking up to 15fps for alarms).

    Going to spend some time coming up with an optimal configuration (smarter motion detection increases processor load, higher frame rate and resolution increases processor load, compromise compromise compromise).

    Going to upgrade the RAM and HDD and see how it handles it. More playing ahead!

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