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Forums Compression Techniques 24p HD to NTSC conversion using Compressor

  • 24p HD to NTSC conversion using Compressor

  • Run Rodriguez

    July 17, 2010 at 5:19 pm

    I’m looking for assistance or a link to help me with settings using Compressor.

    My source footage: 1080 progressive HD 23.97 fps Apple Pro Res 422 Quicktime

    My goal: NTSC progressive 29.97 fps Apple Pro Res 422 Quicktime

    I’ve used Compressor before, but not for this exact conversion. I’d appreciate some assistance through the required Compressor settings. I am using Compressor 3.0.5. Thanks.

  • Mark Spano

    July 20, 2010 at 7:29 pm

    [Run Rodriguez] “My source footage: 1080 progressive HD 23.97 fps Apple Pro Res 422 Quicktime

    My goal: NTSC progressive 29.97 fps Apple Pro Res 422 Quicktime”

    Adding pulldown is easy in Compressor. While I’ve done this conversion plenty of times before, I’ve always gone from 23.976p to 29.97i. The pulldown is generated in the fields and going from 24 images per second to 60 is easy math (24×2=48 + 24×1=24: total=60). Repeating each frame twice gets you 48, then repeating every other frame an additional time gets you another 12, giving you 60 fields in a 2:3:2:3 pattern that’s familiar to the eye. Going from 24 to 30 is probably tougher on the math, since you have to keep all 24 images and add somehow 6 more to the sequence. The math would be (24×1=24 + 24/4=6: total=30). In other words, every frame shown once, and then every fourth frame shown twice, giving you a repeating pattern of 1:1:1:2 – this can’t be nice to watch.

    So frame repeating (a.k.a. adding pulldown) is probably not the way to go for this conversion. Frame interpolation/blending is probably what has to happen. Here’s how I’d set up Compressor:

    In your Video settings tab in Inspector, make sure your codec is set to encode progressive frames:

    Then in Frame Controls, set it like this:

    You’re basically telling Compressor to spend a chunk of time figuring out how to make the best 30 frames out of the 24 you give it.

    Try small sections first to see how it goes. If you want to try the pulldown method, just change the Rate Conversion to Fast instead of Best. You will probably not like the way it looks though.

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