 |
Preparing motion-footage frame rates for final output
When you import motion footage into After Effects, the file's frame rate does not change. If you plan to output your footage to a different frame rate, you can make it conform to the new frame rate in After Effects. Conforming ensures that frames disperse evenly over the new output frame rate.
Conforming footage does not alter the original footage, only the reference that is used by After Effects. When it conforms, After Effects changes the internal duration of frames but does not change the frame content. If the conformation is a large amount, the footage plays back at a different speed. For example, if you change the frame rate from 15 fps to 30 fps, the footage plays back faster.
It's best to make the frame rate the same as the final output frame rate for your project. This way, After Effects renders each frame, and the final output does not omit or duplicate frames. However, in order not to drastically change the speed of your motion footage, it may be beneficial to conform only by a small amount, making the new frame rate divisible by the output rate. For example, if your original footage has a frame rate of 29.97 fps and you want to output it for playback on CD-ROM at 10 fps, you can conform to 30 fps. At 30 fps, the frames are divisible by 10, so After Effects can evenly render every third frame.
Note: If you want to output original NTSC footage as PAL or vice versa, you must have access to hardware that supports each format.
To change the frame rate of a motion footage file:
- Select the footage file in the Project window.
- Choose File > Interpret Footage > Main.
- Select Conform to Frame Rate, type a new frame rate for Frames Per Second, and then click OK.
Note: This procedure can change the synchronization of audio and video files. Be sure to check your files and make any necessary adjustments.