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Activity Forums Avid Media Composer Why does it work? — 720p

  • Why does it work? — 720p

    Posted by Chris Bové on January 2, 2007 at 2:03 pm

    Hi all,

    With a 5-month-old at home that ain’t sleeping the whole night yet, maybe lack of sleep is why I don’t understand this one…

    Workflow:
    – Avid Adrenaline 2.6.2
    – miniDV footage shot 24p (Canon)
    – Dubs made to pre-blacked DVC-pro tapes with new timecode
    – Avid capture at 10:1 for offline edit
    – Avid capture at 1:1 for online edit

    My roots spring up from the 24 frames-per-second film world, and the lack of a telecine in this workflow is baffling me. Why does it work? Am I right that 24p doesn’t use the fields that NTSC uses? If so, are NTSC fields created (unwantedly) in the dubbing process?

    Confusing. Any insights or pointers to literature on this would be most appreciated. Thanks in advance!

    ______
    /-o-o-\
    \`(=)`/…Pixel Monkey
    `(___)

    A picture says 1000 words. Editors give them meaning.

    Michael Phillips replied 19 years, 4 months ago 3 Members · 6 Replies
  • 6 Replies
  • Michael Hancock

    January 2, 2007 at 2:33 pm

    Check this site out:

    http://www.24p.com

    It’s a site run by Michael Phillips, and Avid employee (I believe) who posts here often. It has pretty much everything you might want to know about 24P from what I can tell. I would start there and if you can’t find your answers post back here and Mr Phillips will likely answer you directly.

    Mike.

  • Chris Bové

    January 3, 2007 at 12:05 am

    I agree 24p.com is a great resource. Checked it out – still confused on this question though.

    Anyone?

    ______
    /-o-o-\
    \`(=)`/…Pixel Monkey
    `(___)

    A picture says 1000 words. Editors give them meaning.

  • Michael Phillips

    January 3, 2007 at 1:17 am

    MiniDV is a standard definition format and when these cameras shoot 24p, they do so at 23.976 into a 59.94 field format (NTSC). The imaging and motion capture is done at 1/23.976th of a second with a 48th per second shutter (47.952) which is similar to a film camera at 24fps.

    So the tape itself is very similar to the process of film being transferred to NTSC with a 2:3 pulldown except in this case it is the sensors, a buffer, and writing out to tape.

    These camera adhere to the recommended standard that the “A” frame of the 2:3 cadence falls on non drop 30fps timecode ending on :x0 and :x5. This is why those cameras only record in NDF.

    Now there are two types of pulldown available; NORMAL and ADVANCED. See 24p.com or elsewhere on the web for an explanation of that.

    Is that what you are looking for? I also recommend that you rock your 5 month old back and forth in a 2:3 cadence… they fall right asleep! 😉

    Michael

    anything 24fps

  • Chris Bové

    January 3, 2007 at 7:03 pm

    [MichaelP] “The imaging and motion capture is done at 1/23.976th of a second with a 48th per second shutter (47.952) which is similar to a film camera at 24fps”

    Aaah. Does that hold true with Panny Varicam footage as well? Specifically, 720p @ 24fps? If so, then I may have made an error today when I imported the location audio from hard drive. (An Avid prompt gave me the option to import audio at 30fps instead of 29.97 – which I took).

    ______
    /-o-o-\
    \`(=)`/…Pixel Monkey
    `(___)

    A picture says 1000 words. Editors give them meaning.

  • Chris Bové

    January 3, 2007 at 7:07 pm

    Michael P –

    Sorry… you’ll need more info from me to answer that:
    – final destination is to be 24 fps video for festival projection.
    – possible funding may warrant transfer to 35mm film from master tape.
    – DVD distribution will be small, but definite.

    Thanks!

    ______
    /-o-o-\
    \`(=)`/…Pixel Monkey
    `(___)

    A picture says 1000 words. Editors give them meaning.

  • Michael Phillips

    January 4, 2007 at 5:21 pm

    You will still work at 23.976 since that is the frame rate of the camera. It records in 30 NDF mode for 24 frame on SD formats. If doing double system sound, it is recommended that it be recorded at 29.97fps non drop frame timecode.

    Finish entire film at 23.976 and final film out will be a one to one frame conversion from video/digital frame to film.

    Audio will be adjusted by .1% for the optical track by pulling down the recorder from 60Hz to 59.94.

    Digital audio for film will have a sample rate conversion done to go from 23.976fps @ 48kHz to 24fps @ 48kHz.

    DVD, SD, and HD masters will all live at 23.976/48kHz which is what you have now in editorial.

    Michael

    anything 24fps

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