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Stuttering Playback for Uncompressed Clip in FCP, but not in Quicktime

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Thomas Reed
Stuttering Playback for Uncompressed Clip in FCP, but not in Quicktime
on Apr 19, 2012 at 9:52:39 pm


I'm writing to ask for feedback about trouble I'm having playing a clip in FCP 7 that plays fine in QT 10. More details are below, but the short version of my question is: if a clip plays fine in Quicktime 10, then shouldn't it also be able to play smoothly in FCP7?

Here are more details --

software versions:
FCP 7.0.3
Quicktime 10.1

My system:
OS X 10.7.3
Processor: 3.4 GHz Intel Core i7
Memory: 12 GB 1333 MHz DDR3
Graphics AMD Radeon HD 6970M 2048 MB

RT settings:
Scrub High Quality
Playback Video Quality: Dynamic
Playback Frame Rate: Dynamic
Record to tape: Use Playback Settings

Sequence settings:
Frame size 1920 x 1080
Aspect Ration: HDTV 1090i (16:9)
Pixel Aspect Ratio: Square
Compressor: Uncompressed 10-bit 4:2:2
On the Video Processing tab, "Render 10-bit material in high-precision YUV" is checked.
(these were created by dragging the clip onto the timeline and clicking YES to change sequence settings to match clip settings.)

The drive hosting the clip is an internal 1.5 TB drive that came with the computer. It is has 500 GB still free.

The clip I'm working with is formatted as Uncompressed 10-bit 4:2:2 | 23.98 FPS | Data Rate 1.06 Gbit/sec | 1920 x 1080

This clip plays fine in Quicktime (10.1), but when I play it with my FCP (7.0.3) then it stutters. To be clear, when I hit PLAY there is a short pause (which I don't normally see when working with lower resolution video), then the clip starts playing correctly for a few seconds and then it starts to stutter and often the playback will freeze even though the scrubber is still moving through the timeline. I have this stuttering problem with these sorts of clips whether I play them in the Canvas or the Viewer. I have created other clips with these same uncompressed settings, and have the same stuttering problem. I do not have a stuttering problem if I play ProRes or H.264 files in FCP.

To date, I've taken these steps:

  • Checked Activity Monitor to verify that my system has enough memory and processing power. Activity monitor shows that there's plenty of excess memory and CPU capacity while I'm working with these files.
  • Tested my memory with Rember (memory is fine)
  • Trashed my preferences and reimported the uncompressed clip.
  • Run software update to be sure everything is up-to-date (it is)
  • Checked permissions on the drive that hosts the clip. It's fine.

None of these steps has enabled my to play an uncompressed clip in FCP with out it stuttering.

My questions are:

  1. should my system, which is a top of the line iMac, be able to play uncompressed QT files in FCP?
  2. If the clip plays in Quicktime, then shouldn't it play correctly in FCP?
  3. If the answer to these two question are YES, then I'd appreciate any other suggestions for what I can do to get FCP to play the uncompressed files smoothly?

My fall-back option is to convert these clips to ProRes - but considering laying this project back to film and so want to have the highest quality possible.

Thank you for your help & feedback!


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