Avid Express Pro HD and Frame Rate Conversions

There are times in a production when the footage only exists in one format and the user needs it in another. A common example is a 24p project being handed an establishing shot on digibeta. In this case, the footage is interlace, 60 fields at 30 frames per second, while the project type is progressive and 24 frames per second.

Using the Timewarp effect - part of the FluidMotion effects engine in Media Composer Adrenaline HD and Avid Xpress Pro HD - the user can create alternate frame rates and keep the original audio in sync.

The Timewarp effect can be used to create all the frame rate conversions needed. The table below gives all the values needed to crate any frame rate.

1.Create 30I NTSC project
2.Capture shot to be converted
3.Edit onto timeline (V and A)
4.Apply the Timewarp effect from the effects palette
5.Select FluidMotion from the Render Using menu
6.From the Formats menu, select Interlace as input and Progressive as Output
7.Open the Speed graph and enter 125 into value entry box at the bottom of the window.
8.Render

The result will be a progressive clip of the same duration but now running 125% faster. When this clip is imported back into a 23.976p project, it will be slowed down by 25% due to the 1:21 frame relationship. This way, durations remain the same and the original audio remains in sync.

In order to get the clip back into a 23.976p project, export V only as a QuickTime reference and the audio as a WAVE file.

Import these two files back into a 23.976p project and sync the V-only clip with the A- only clip using AutoSync.The result is a sync VA clip in a 23.976 frame progressive format.

When importing the QuickTime file into the 24p project in either Media Composer Adrenaline HD or Avid Xpress Pro HD, the user may see a message indicating that the source is interlace in a progressive project. Click OK and continue.