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Thread: Linux multicam

  1. #1
    Join Date
    Jan 2009
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    466

    Default Linux multicam

    Hi there,

    My brother owns a rock club in Seattle. One of the things that he offers to performers is a copy of the raw individual tracks of their performance from the board. Bands are crazy about this as the quality is 'almost' good enough that they are a Protools session short of releasing a live CD (overdub any flubs, mix down, master, release).

    One of the things that we were considering was to incorporate video. The Logitech C920 is relatively new and capable of bit streaming h264 1080P@30fps (it features a hardware encoder). We were considering picking up four or five of them and mounting them at static positions around the stage, and simply bit streaming to a file using the V4L2 interface, allowing bands to create a polished Live DVD/BD/Stream.

    Has anyone ever done anything like this before, outside of purpose-built surveillance boxes and really expensive studio-quality boxes? Does anyone know of a relatively inexpensive NLE that will allow the use of a virtual camera via a composite of the captured feeds? Does anyone have suggestions that will allow us to increase the USB cable length to a usable length (probably up to 30 feet in some cases, and I can't just duct-tape a bunch of hubs to the walls)?

    I'm still in the data collection phase. Budget is ~$1000. We can get the cameras for ~$80 each ($400-ish for 5 of them, leaving 500 for a PC and $100 for usb range/cable extensions).

    Dumb assumptions brainstorm:
    *Use EXT2 with noatime (no data retention, everything burned to BD after the show).
    *Build simple UI with record and stop buttons. Only other input will be band_name
    *file names concatenate band_name-camera_name-{date}.mp4
    *Figure out the V4L2 driver situation (drivers in git, not ready, cannot select bitrate yet)
    *No more than 2 cameras per USB hub due to bandwidth limitations, even when using the h264 stream. Need to find cheap MBoard with at least 3 hubs

    F
    Last edited by russofris; 06-26-2012 at 09:18 PM.

  2. #2
    Join Date
    Feb 2008
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    Linuxland
    Posts
    5,185

    Default

    For long USB runs, there are products that do the "long" part either via ethernet cabling or optical one. The first is good for 100m and the second even longer.

    Though, as you list the usb bandwidth as a limit, why not cameras with network ports? GigE + a good switch should let you run many cams at once.

  3. #3
    Join Date
    Jan 2009
    Posts
    466

    Default

    Quote Originally Posted by curaga View Post
    Though, as you list the usb bandwidth as a limit, why not cameras with network ports? GigE + a good switch should let you run many cams at once.
    If you know of a 1080P@30fps IP based camera that does h264 encoding (on the camera), suitable optics, and auto focus, that costs $80, I'm all ears. When I look, I find security related cameras that cost over $400 for a single camera.

    While I'm not going to claim that the c920 is great by any means, it certainly gives you a lot for the cost. I linked a USB extender in my original post, but have no idea whether or not they will actually work for what I am attempting.

    On a side note, I spec'd out a Llano A6 platform on Newegg with a 1.5TB HDD and BD burner. It came to just under $500 without monitor. I'm also looking at some of the surplus HP Touchsmart PCs, which may do the job as well for the same price, but would include the monitor and input devices.

    F

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