Avid 24fps Audio Q&A

>>If I digitize my material into a film project with a 29.97 videotape and the pulldown switch set at .99, does the audio speed back up in the Avid to 30 fps (from 29.97) and the video to 24 fps (from the 23.976 speed on the video tape)?<<

When in a 24fps project, the video is played back referenced to 30Hz (at 24fps rather than 23.976), when the switch is at 1.0.

When the switch is at .99, the audio taken off a videotape is sampled at 44.056 or 47.952, while digitizing), and played back at 44.1 or 48, so it speeds back up to its original rate, when the switch is at 1.0. If you leave the switch at .99, the video and audio are played at the pulldown rate (29.97).

>>Do they mix to video and then when they are done mixing speed up their mix by .01% to it can be laid onto the optical track?<<

Yes. You can mix to a video output of the show, which is referenced to 29.97Hz, and then pull it up to match the film print by referencing the playback to 30Hz. (or 59.94 and 60Hz, if you prefer)

>>Also, when working on a film project, what happens if you do a digital cut and you switch the pulldown from .99 to 1.0?<<

re. Digital Cut: If you select Film Rate and .99, the picture is running at 23.976fps, while extra fields are inserted, and you get a normal video copy at 29.97.

re. Digital Cut: If you select Film Rate and 1.0, the video runs at 24fps, while extra fields are inserted, This was done for output to tape for AudioVision. (note: this method drops 1 frame per 1000)

>>...for video, would it just record only the 24 fps a second I have been cutting with on the Avid (thus my tape would run 20% faster than real time, because their are no bogus fields on it)?<<

re. Digital Cut: If you select Video Rate and 1.0, you get a film frame for each video frame and it will play fast in the VCR. This is done for neg. cutters who use a lockbox without removing extra video fields.*

>> What would happen to the audio with the pulldown switch put at 1.0, let's say if I laid it off to Tascam, would it speed it back up to it's original 30 fps...?<<

Anytime you play audio out at 1.0 it is running in sync with the 24fps film, 30/60Hz. (i.e., it will sync with the projected print)**

>>I have a sound editor asking for a Tascam with a "frame rate of 30 NDF with pulldown", BUT I thought 30 with pulldown is 29.97?!<<

If you make the TASCAM tape with the switch at 1.0 and put 30fps TC on the tape (NDF prefefrred), then the sound people can either play it at 30 or 29.97 in their system. There are a number of ways to get there-from-here; they may want the tape pulled down, so you would output at .99, like making a videotape, with 30fps TC. If that is what they want, then they will compensate somehow on their end when making the master for your optical track.

>>Also, when working on a film project at 24fps in Avid, when would it would be necessary to put the pulldown switch to 1.0? <<

**When making a mag track to sync with a cut print, for example. Also, when you import CD audio or digitize anything that has not been pulled down, you want the switch at 1.0. When you are editing, you will be editing at the rate determined by the switch (1.0=24fps; .99=23.976fps), so the best rule is to never have the switch at .99 unless you are digitizing from video tape, or some other pulled down source.

>>I can only think it would be necessary for a neg. cutter who wants to see the exact burn in keycodes of the ins and outs of each shot (to avoid looking at false fields), and doesn't care about the duration on the reel.<<

*Neg. cutters will tell you if they want the frame-for-frame copy or a normal video with extra fields. They can use either one.

Back to the Audio Considerations page.

Link to Avid Technology, Inc. for more technical info regarding Avid products.
Link to Filmmaker's Home Page/ Editing.
Link to Zerocut main page.
e-mail Alan Stewart.