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4 SD Inputs



  • I'm planning a project where I would like to simultanously capture 4 live feeds from SD Sony PTZ cameras to disk and then after stopping the capture to imediately playback the files cutting between the 4 movie files and output to a single projector. I have two 2010 MacPros (2.66GHz Quad-Core Intel Xeon, 6GB Ram, 640GB 7200-rpm Serial ATA 3Gb/s, 2x NVIDIA GeForce GT 120 512MB) at my dispossal and am trying to work out the most economical but stable way to achieve this? The two options I'm considering at the moment are:

    1\. Purchase a LFG 4 from active silicon ([http://www.activesilicon.com/products_fg_lfg.htm](http://www.activesilicon.com/products_fg_lfg.htm)) and use a single Mac Pro
    2\. Use two Mac Pros with separate capture cards and somehow transfer the files once captured for playback on one of the mac pros.
    Any suggestions?
    Thanks
    Simon


  • Dear Simon,

    If you can wait a couple of days, I can attempt to run a capture with the LFG4 and four live streams to see how it performs. Please send me a private mail (i.e,. @troikatronix.com) to remind me please.
    I think transferring the files will be a bit of a nightmare. Though I wonder if, using a Gigabit Ethernet, you could just record on Networked drives (i.e., record to the target computer in the first place.) 
    Maybe Mehdi (who seems to know these networks) has a thought?
    Best Wishes,
    Mark


  • Hi,

    I would say that it can work with only one macpro, but I'm afraid a single HDD will be a bottleneck for capturing 4 simultaneous streams. 
    In the case of two machines the network connection will be the bottleneck ( or you go for fibrechannel but then I can't advice )
    You're lucky, SSDs are getting cheaper ! You need one or two (spreading the medias ) mounted internally.
    If I was you I would use the Blackmagic Disk Speed Test ( you can install and use it even if you have no blackmagic card ) 
    It will give you direct infos about how many fps of any video size you can record on your drives.
    Also don't trust theorical speeds for ssd, I am afraid the will be anyway limited by the sata2 controller of the macpro. 
    Best
    Mehdi


  • Thank you both very much for the advice. Mark it would be fantastic if you could test the LFG4 for me - I'll email you.

    Best 
    Simon


  • Dear Simon + All,

    Some preliminary results for you. 
    Recording four channels of LFG-4 to disk:
    Mac OS 10.6.8
    MacPro 2 x 2.8 GHz Quad-Core Intel Xeon
    RAM: 4GB 800 MHz DDR2
    7200 RPM Drive: FPS = 17, Cycles = 55, Resulting Clip FPS = 21
    **10000 RPM Drive: FPS = 30, Cycles = 106, Resulting Clip FPS = 29.42**
    SSD Drive: FPS = 11, Cycles = 41, Resulting Clip FPS = 12,26 (!!!!!!!!!!!!)
    Now, I have to throw in lots of exclamation points next to the SSD drive. Does anybody have any theories as to why the SSD would be the **slowest of all**??? Is it because reading is super fast, but writing is worse than a regular drive. Or????
    [EDIT: search for "ssd drive write speed slower than normal drive" (without quotes.) A lot of entries appear... so it appears some further research on SSD write speed will be necessary.]
    But the main point, as you can see, is that with a fast drive, you can do the capture.
    I'll get a full report with record and play speeds later. But that's the initial feedback
    Best Wishes,
    Mark


  • Hi Mark,

    I guess answer is yes, but are you testing all the drives on the same bus ( what kind? )?
    What's your SSD ? it should be definetly faster ! Read and write are normally fast.
    Would you run a speed test ( blackmagic software ) on each drive ?
    Best
    Mehdi


  • Hi Mark

    Thanks you for taking the time to test this and fantastic news that it is possible to do the capture. I'll research the SSD issue further... 
    Best 
    Simon


  • Has anyone any experience of using isadora with multiple Blackmagic Intensity Pro cards in a single mac pro? I suspect that Isadora might not recognise them as individual inputs as they are the same model?? The Blackmagic website says this. If it works I was thinking that perhaps buying 4 Blackmagic cards with HD capability might give me more felxibiltiy for future projects than an SD LFG4.

    Thanks
    Simon


  • Dear Simon,

    Well, I can tell you that the Blackmagic Deck Link Quad shows up as four individual inputs. (I haven't tested four at a time though...) Because this card is essentially four Deck Links in One,  I suspect that multiple Black Magic cards will show up as separate devices. But I cannot say with totally confidence without trying it.
    Best Wishes,
    Mark


  • Black Magic support emailed the following about multiple Intensity Pro cards in a Mac Pro:

    _'I am afraid but we do not certified this software for your kind of workflow - we certified the use of only one card a time per system. However we are aware of people using multiple card within their system, using software like Wirecast, Softrone, BoinxTv. Again, we do not certified them and we can not guarantee that this configuration is going to work as expected.'_
    ...not much help really so I'm trying to find a supplier that will test it before I buy.

  • Tech Staff

    Might be worth contacting Anthony Hammond from jigsaw (UK based) he is currently working on a similar thing and he is aware of isadora and it configurations. He generally has access to blackmagic hardware, macs and Isadora, etc

    [http://www.jigsawaudio.com/about/Anthony-Hammond](http://www.jigsawaudio.com/about/Anthony-Hammond)


  • Thanks Graham I'll try Jigsaw.



  • Dear Simon,

    Thing is, I have the DeckLink Quad, and thus I should be able to try it -- problem is, it only accepts SDI input, which is kind of an unusual beast. What I did try was to capture from the output of the Deck Link back in to one of it's inputs -- that works, no problem. And I can definitely verify that all 4 inputs (and all flavors of those inputs [e.g., NTSC, PAL, HD, etc.]) appear in the Live Capture Settings dialog. What I can't do is try a 4 way simultaneous capture.
    But, in theory, you can do it with the Deck Link Quad. And like I said, that likely means separate Deck Link cards as well.
    Best Wishes,
    Mark


  • Dear Simon,

    To follow-up on Mark's post -- I was able to do some capture tests of 3 streams a few months ago with the same deck link quad card and had somewhat mixed results. With 3 streams I would see a significant number of dropped or duplicated frames, and/or bad artifacts.

    I don't have the quad handy currently but I'd be happy to pass my test notes on to Mark in case recent changes in izzy may have helped out with the dropped frame issue.

    Best,

    Ian


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