Frame Rate Conversion

There are times in a production when the footage only exists in one format and the user needs to use it in another. A common example of that is a 24p project being handed an establishing shot that was 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, 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, but we will use the 60 field interlace to 24p as the example. The table below gives all the values needed to create any frame rate needed. There is also a bin available here that has all of the frame rate conversions as a preset template.

The user needs to capture the footage to be converted in its native project type. The example below is for converting 60 field NTSC material to 24p (59.94 fields into 23.976p), a 30i project will be created and the footage to be converted captured. The user will want to use the highest quality possible since the rendered timeline will become their new source master.

Create 30i NTSC or 25i project
Capture shot to be converted
Edit onto timeline (V and A)
Apply the Timewarp effect from the effects palette
Select “FluidMotion” from the “render using” menu
From the “formats” menu, select “interlace” as input and “progressive” as “output”
Then open the “speed” graph and enter "125" into value entry box at the bottom of the window
Render

The result will be a progressive clip of the same duration but is now running 125% faster. The reason for this is that when this clip is imported back into a 24p 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 24p project, export V only as a QuickTime reference and the audio as a WAVE file.

Import these two files back into a 24p project and sync the V only clip with the A only clip using AutoSync and the result is a sync VA clip in a 24 frame progressive format.

When importing the QuickTime file into the 24p project in Media Composer Adrenaline HD and Xpress Pro , the user may see a message indicating that the source is interlace in a progressive project. Click “OK and continue.” For versions 4.6 and earlier, the user can export sequential graphic files as workaround to the QuickTime interlace import issue.

Below is a table showing the value and settings for the most popular frame rate conversions:

NTSC
FROM	TO
		SPEED	INPUT	OUPUT
29.97i	24P	124.88	interlace	progressive
29.97i	25p	119.88	interlace	progressive
29.97i	23.976p	125.00	interlace	progressive
29.97i	25i	119.88	interlace	interlace
29.97i	29.97p	100.00	interlace	progressive

29.97p	24p	124.88	progressive	progressive
29.97p	25p	119.88	progressive	progressive
29.97p	23.976p	125.00	progressive	progressive
29.97p	25i	119.88	progressive	interlace
29.97p	29.97i	100.00	progressive	interlace

PAL
FROM	TO
		SPEED	INPUT	OUTPUT
25i	24p	104.17	interlace	progressive
25i	23.976p	104.27	interlace	progressive
25i	29.97p	83.42	interlace	progressive
25i	29.97i	83.42	interlace	interlace
25i	25p	100.00	interlace	progressive

25p	24p	104.17	progressive	progressive
25p	23.976p	104.27	progressive	progressive
25p	29.97p	83.42	progressive	progressive
25p	29.97i	83.42	progressive	interlace
25p	25i	100.00	progressive	interlace



23.976/24p
FROM	TO
		SPEED	INPUT	OUTUT
24p	25p	96.00	progressive	progressive
24p	29.97p	80.08	progressive	progressive
23.976p	25p	95.90	progressive	progressive
23.976p	29.97p	80.00	progressive	progressive

For 30i to 60p (29.97i to 59.94p) use a speed of 50%, INPUT interlace and OUTPUT progressive.

The.abv file contains presets for all the frame rate conversions listed in the above table. These presets will work in both Media Composer Adrenaline HD and Xpress Pro HD. Add bin to project and open as you would any other bin. Download Bin