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  • Posted by Peter Fagan on August 30, 2015 at 5:51 pm

    I’m masking out some head switching noise at the bottom of a clip.

    I could add a bottom crop to the clip or I could put a thin black bar on the track above.

    Is the system smart enough to delete cropped frame data without recompression?

    If not, is there really any difference to the quality of the recompressed frame between those two approaches?

    Nick Meyers replied 10 years, 8 months ago 2 Members · 5 Replies
  • 5 Replies
  • Nick Meyers

    August 31, 2015 at 2:24 am

    new frames will have to be created either way.
    quality will be identical with both approaches.

    nick

  • Peter Fagan

    August 31, 2015 at 12:27 pm

    Sets my mind at rest to know for sure — thanks.

  • Nick Meyers

    August 31, 2015 at 9:43 pm

    There is a slight difference, though.
    Crop is measured on a scale from 1 to 100, so it might not fall perfectly on a pixel.
    A mask can be positioned to the pixel, so can have a sharper edge.

    Nick

  • Peter Fagan

    August 31, 2015 at 10:23 pm

    Yeah, I’d noticed that. I busted out the calculator, zoomed screenshots and divided by 4.86 to get some on-the-pixel crop values.

    My new adventure is that I occasionally have to drop 720×480 clips into a mostly 720×486 sequence. The smaller clips seem to get blurred a bit even when the motion tab says they’re not scaled or distorted. Perhaps I’m just misunderstanding an attempt to illustrate the interlacing.

    Unearthing the treasures of portapak…

  • Nick Meyers

    September 1, 2015 at 3:36 am

    i don’t work with those frame sizes (i’m in PAL land)
    but my understanding is that FCP places them correctly, and crops a few pixels from top & bottom.
    (4 from top, 2 from bottom or the other way around)

    slight blur could be because you haven’t rendered yet?

    nick

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