causes of digital noise in final cut rendering?

Discussion in 'Mac Apps and Mac App Store' started by michi, Apr 24, 2004.

  1. michi macrumors newbie

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    #1
    I have been rendering rather large files in final cut express, in which i've noticed digital noise (dirty pixelation) occuring in sporadic bursts of maybe a minute or so, for around 6 frames each time. I was wondering if anyone has come across this and knows of possible causes, or ways of stopping it occuring.. ?


    I would just like to add now that I am almost certain this is an exporting/rendering problem, as it has occured at different points on exports of the same files...
     
  2. stoid macrumors 601

    stoid

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    So long, and thanks for all the fish!
    #2
    Can you give a little more information on the static?

    I'm guessing it's not on the frame before you render.

    Is it happening with only certain effects/transitions/titles?

    Are you using clips imported from a video camera over FireWire, still images, or converted video?

    How heavy is the static? Does it consume the entire image, or is it just a minor detail the casual observer might not even notice?
     
  3. Sun Baked macrumors G5

    Sun Baked

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    #3
    G5, dual monitors, ATI 9600/9800?

    In the file, or just the playback?
     
  4. michi thread starter macrumors newbie

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    #4

    Sorry, I really didnt put enough info earlier (obvious it's my first post..). I am having these static noise problems only in the final cut movie export attempts. There appears to be no problems in the original final cut express files. I am using still images for the whole sequence - photoshop and tiff files. The actual images are black and white pen drawings - no colour is involved, and yet there is a lot of coloured pixels in the noise..don't know if that is standard for noise or not, no matter what the original image is like. The static is occuring only on one layer in the timeline - you'll see by the pic I am hopefully attaching that the two layers of white over top are not affected. The sound is not affected in the same periods of static. It is not the whole clip that is affected - the static is occuring over regular time intervals over the periods of time when it does happen so it doesnt appear to have anything to do with effects or transitions. I would say this is the main point to note - that when these patches of static noise occur, it happens in a regular cycle - of about 2 a second. I am editing on a powerbook G4 - video card radeon 9600. Thanks for looking at this...




    [​IMG]
     
  5. Rower_CPU Moderator emeritus

    Rower_CPU

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    #5
    I've seen similar noise due to a bad capture or drive problems. I'd check both of those.
     
  6. michi thread starter macrumors newbie

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    #6
    As it couldn't be due to capturing - I've just imported picture files that have been fine in any uncompressed final cut express file so far, then its possible it could be due to the drive?! Hope not, just bought this 17"powerbook recently enough.. What sort of drive problems have you seen cause this sort of noise?
     
  7. Rower_CPU Moderator emeritus

    Rower_CPU

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    #7
    I had this happen to me on a Firewire drive that went bad - required a reformat. Hopefully, this isn't what's happening to you, but I'd try backing up my media and working off a different drive/partition if you can.
     
  8. h'biki macrumors regular

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    #8
    Make sure your image files are NOT grayscale, but colour. Also, I recommend working with JPEG or PSD files, not TIFF. FCP (and presumably FCE) just don't like TIFFs too well.
     
  9. michi thread starter macrumors newbie

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    #9
    Can I ask why it matters whether it is grayscale or colour? And TIFF as opposed to PSD or JPEG - as I thought TIFF was the better file for picture manipulation etc. I have hundreds and hundreds of pictures i've had to edit together, so the thought of having to change every file makes me feel slightly (or very) ill! Also, the fact that this static noise isn't occuring all the way through at all, and at such regular intervals when it does, makes it seem to be a seperate problem to the files themselves...
     
  10. h'biki macrumors regular

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    #10
    From experience :) Grayscale images create weird render problems, I've found.

    I think (and this only a theory):

    Final Cut prefers to work in video's YUV colour space (unless you tell it otherwise), still images areusually in RGB. FCE/P has to then convert the RGB files into YUV. It is expecting an 8 or 16bit colour file, and when it gets a grayscale file not in the RGB colour space, it freaks out and causes problems. Both Photoshop Elements and Graphic Converter shoudl let you batch process your images and convert them to RGB.

    PSD is as uncompressed as TIFF. FCP/E is optimised to work with the format -- supporting layers and PS metadata.
     
  11. michi thread starter macrumors newbie

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    #11
    " From experience Grayscale images create weird render problems, I've found. "



    my images, even though black and white - are saved as RGB's. Would just the fact then that there many TIFF files cause wierd render/exporting problems?
     
  12. h'biki macrumors regular

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    #12
    Could do. They certainly eat through RAM. Are the artifacts repeatable? Do they reoccur at the same places whenever you render?
     
  13. michi thread starter macrumors newbie

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    #13
    I've definitely discovered the TIFF eating RAM issues...The noise problems however occur at different times each time I render...
     
  14. h'biki macrumors regular

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    #14
    Are you capturing to an external drive? What version of QT and FCE are you running?
     
  15. michi thread starter macrumors newbie

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    #15
    I haven't been capturing to an external drive ( although i'm now in the process of shifting it all to one - this noise was happening long before i have started copying it all onto an external drive..may as well ask - do you know if you have to seperately reconnect every render file etc when shifting everything, including the programme itself, to an external drive?)

    Version of FCE is 1.0.1
    QT is 6.5
     

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