Joe’s Frame Rate Adjuster changes the apparent frame rate of a clip without modifying the timeline settings. The filter is field based and plays clips at any frame rate from 1-60fps. Potential uses include simulating film motion and helping with standards conversion. Setting NTSC video to 24fps outputs correct 3:2 pulldown (3 clear frames, 2 judder frames).
This effect works by translating a clip’s default playback framerate to a virtual framerate and then resampling fields and frames for playback. Duration is calculated to the field playback rate for smoother motion. De-Interlacing is automatic when the framerate causes fields to stretch across multiple frames.
Example Images
Click to open movies in new windows:
Note that these preview movies are encoded at 60fps to attempt to preserve their original motion. Because this plugin is made to work with interlaced video, the best way to preview the effect is to download the demo and see them on an external video monitor.
Standards Conversion: NTSC < -> PAL
Some users have reported success using Joe’s Frame Rate Adjuster for translating between PAL and NTSC video in Final Cut Pro. To change from NTSC to PAL, try setting the fps to 50 or 25. Because the filter is field-based, 50fps should result in smoother motion. To change PAL to NTSC, set fps to 29.97.
Interlacing and Still Frames
To create the virtual playback framerate, Joe’s Frame Rate Adjuster makes optimum use of the timeline’s field playback rate. Because of this some virutal frames may exist across more than one field. This results in what is referred to as a ‘judder frame’. These frames are normal and will not be seen during playback.
Mixing Actual Frame Rates
Final Cut Pro’s default behavior regarding unmatched actual framerates may cause unexpected results with Frame Rate Adjuster. When clips with non-matched framerates are inserted into a timeline, FCP automatically interpolates the clips to match the timeline’s framerate. This means that a true 12fps clip placed into a 29.97fps timeline will be processed as if it’s framerate were 29.97. Unfortunately FCP doesn’t do a particularly good job of interpolating these new frame rates. At first I thought this might be a bug, but it’s consistant with other FXScript effects behavior. I’m continuing to look for workarounds and options for standards conversion, feedback is welcomed.
Controls
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Frame Rate (1 - 60)
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Sets the virual playback framerate for the filtered clip. This value is field-based so interlaced clips can be played back at any value up to their actual field rate. NTSC can playback at anything up to 60fps and PAL playback at anything up to 50fps.
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Motion Trail (0 - 100)
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Blends the current virtual frame with the next actual frame to help ease strobing and smooth out motion information lost between virtual frames. Setting Motion Trail to zero shows only the current virtual frame.
Feeds