24 Frame EDL Creation from Video Based Projects (NTSC & PAL)
New in version 11 of Avid Media Composer™, Avid Film Composer™, version 4 of Avid Symphony™, and version 3.5 Avid Xpress™ and on Avid Xpress DV v3.5 (option) is the ability to create a 24 frame EDL from a 30 frame project using sources from a 24p HD master.
The need to create a 24 frame EDL is for programs that need to go to create a 24p master from the original sources but the project was edited in a 30 frame environment from the down converted submasters. This workflow assumes that the 30 frame sources were down converted from a 24p HD master and contains 2:3 pulldown in NTSC or with a 4.1% speed up in PAL.
Other documents on this website explain the 2:3 insertion process for NTSC and the speed up for PAL, but a quick review is as follows:
1.) NTSC - In order to create 60 fields of NTSC material, fields are added to the original 24 frames. This is referred to as 2:3. It is named 2:3 because the first frame of the pulldown sequence is frame 1 = 2 fields long, followed by frame 2 = 3 fields. This pattern repeats itself for the duration of the shot. In doing so, what used to be 24 frames is now 60 fields creating NTSC video. For the sake of simplicity, this document refers to 24 and 30 as whole numbers, but NTSC is actually 29.97fps and 24p HD can be either 23.976 or 24 depending on how the original material was captured. Timecode between the 24 and 30 will sync at the top of every second, but will differ within the second depending on the pulldown phase at the point in time. A common practice is to have an "A" frame always coincide with non drop timecodes ending in "0" or "5". Avid products can work with either drop frame or non drop frame timecode when creating 24 frame EDL's, non drop is preferred in the post process since the relationship is repeatable throughout the duration of the material making it easier to verify that the pulldown and timecode relationships are continuos.
2.) PAL -PAL is created by the VTR playing back the material faster to create a 2:2 pattern where every original frame is always 2 fields in length. In doing so, the program will now play back 4.1% faster than the original. In cases where audio pitch is not corrected, the pitch is raised by .7 of a semitone. When creating PAL down converts, the timecode gets recalculated from 24 to 25. VTR's offer several options for doing the 24 to 25 conversion, but it is HIGHLY recommended that the setting be set to recalculate from 00:00:00:00 (referred to as midnight) see VTR manual for further instructions.
Once the material has been digitized in either a 30i or 25i project, the "Start" timecode column reflects the sources from which the material was digitized. In the case of a NTSC editorial process, the "Start" timecode column will be 30 frames drop or non drop, or even mixed (also supported).
EDL Creation Steps
1.) Highlight the entire "Start" timecode column by clicking the on the column name.
2.) Depending on platform OS, do a "command-D" or "ctrl-D" (duplicate command) and a new dialog box will appear. This dialog allows the user to designate a target column in the bin. The user can select any of the timecode columns or even custom columns. Custom columns will store the timecode as a text string rather than as a timecode that counts. Scroll down until you see the "TC 24" column name. This is the column dedicated to tracking and counting the original 24 frame timecode from the HD masters.
3.) Click OK. In PAL projects, the users will be presented with another dialog box based on the type of down convert that was done. As mentioned earlier, it is HIGHLY recommenced that the down conversion process be recalculated from 00:00:00:00. If this is the case, then select "convert". The other option is to "copy" Copy is a straight sync point copy of the timecode with no recalculation, but will start counting as 24 instead of 25 frame that point on. This is common when recording DAT on set and the production timecode is 24. The DAT players do not have the option of recalculating from 00:00:00:00. Setting the deck to 25fps allows deck control and timecode, to work, but the copy/paste of the timecode allows for correct EDL's to be generated for the original audio sources.
After clicking OK, the TC 24 column will not have the correct timecode as found on the original 24p masters.
4.) Open the sequence in EDL Manager and make sure that the two menus under the "source" and "record" are set to 24. Update EDL and a 24 frame EDL is created in the EDL format of your choice.
NTSC Users Be Forewarned!
In order to have the most accurate matchback, pulldown identification must be correct. Without the "Pullin" column being logged, the system will assume that the "A" frame is on either "0" or "5". Although this is a recommended practice, it is not a guaranteed practice as equipment or user error can be introduced in the process. When these changes do occur, it is not necessary to retransfer, or perform another down conversion of the sources. All one needs to do is correct the pulldown phase ID in the "Pullin" column. Enter A, B, C, or D based on the correct timecode to pulldown phase relationship. Not having a proper relationship logged will result in greater than expected +/- 1 frame errors. When the pulldown phase is properly logged and being tracked, there should NEVER be more than a +/-1 adjustment at any one point. This is a key differentiate in systems that track pulldown as part of the matchback process for EDL or cutlist for negative conform versus those that do not and make "A" frame assumptions.
See 2001 SMPTE Presentation on this subject
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