Scrubbing/Playback of Red RAW Footage

Discussion in 'Digital Video' started by RoverStar, Aug 26, 2015.

  1. RoverStar macrumors newbie

    Joined:
    Jun 26, 2013
    #1
    I'm wondering if someone can help me figure out why exactly Red RAW footage doesn't play or scrub smoothly, specifically in editing with FCPX. Supposedly, my Mac's SSD can handle read/write of 1gbps. Based on a calculation I found, the Red footage's data rate should be around 600mbps for my 5k, 29.97fps video, but on playback and scrubbing it plays maybe every 10 frames at best out of a framerate of 29.97fps.

    So obviously something else is going on that I can't figure out. Aside from just transcoding as a solution, can someone help me figure out either a more accurate data rate, or at least explain why I'm wrong in thinking it technically should play smoothly? Many thanks.
     
  2. Gwendolini macrumors 6502

    Gwendolini

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    #2
    What kind of footage do you have?
    What resolution does the footage have?
    What codec does the footage use?
    What Mac do you have?

    And do you mean 1 GByte per second or 1 Gbit per second?
    And 600 MB/s seems rather high, as the Red Epic Dragon has a data rate of 128 MB/s for 6K footage at 30 fps and REDCODE 7:1.
     
  3. ColdCase macrumors 68030

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    #3
    Otherwise... Is there anything else the Mac or FCPX is doing in the background, like rendering. And have you restarted the Mac recently? Finder issues can play havoc with FCPX. Have you run a black magic speed test on that internal SSD just to check its performance?

    My internal rMBP SSD does do near 1GBps per blackmagic's benchmark.

    If you import the video and walk away for an hour, is scrubbing performance improved when you return?...
     
  4. RoverStar thread starter macrumors newbie

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    Jun 26, 2013
    #4
    The footage is of real estate. Fairly slow moving pans mostly. It's all the raw footage out of the camera, not transcoded. (Based on our workflow, transcoding isn't an option right now, nor are proxies.) We're in Redcode 8:1 and using the new Mac Pros.

    I calculated the data rate from here: http://www.theblackandblue.com/2011/03/12/how-to-calculate-red-camera-data-rates/. The resolution is 5120 x 2700.

    Background rendering is off. Due to time constraints, even on the Mac Pros it isn't feasible for us to prerender, transcode or generate proxies with the amount of footage we're producing. I know that makes it more difficult for us, but that's what we have to deal with at the moment.

    Still, it doesn't make much sense to me why a hard drive with no other activity that's capable of 1gbps shouldn't be able to play or scrub video that's far from that max rate. My Blackmagic test found read/write between 800-900mbps. Even without a solution, I'd at least want to figure out the reason as a first step.
     
  5. Gwendolini macrumors 6502

    Gwendolini

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    #5
    I used this to calculate data rate, and 68 MB/sec is 544 Mbit/s.

    http://www.red.com/tools/recording-time

    How does the footage play back in RedCineX-Pro? Does FCP X have a display quality setting like Premiere Pro does, where you can say, it only has to render half or quarter of the image?
     
  6. RoverStar thread starter macrumors newbie

    Joined:
    Jun 26, 2013
    #6
    Even in Redcine, it has to buffer until you take it down to about 1/4 quality. FCPX only has two options for display-- quality or performance. Probably full or 1/2. Can't go less than that.

    So the byte vs bit. The calculation I originally had was in MB, not Mb. It seems like it would make sense as to why playback would be choppy-- 592MB/s equates to 4.8Gb/s, when the capacity is only 1Gb.

    According to that Red link you posted, the data rate says 79MB/s, which is .63Gb/s. You'd think the computer and network could handle it, but apparently not.
     

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