Adobe After Effects is a digital video editing suite that allows users to modify various aspects of video clips. With After Effects a user can change the way a video looks when played back, including color correction, light balancing and special effects. After Effects also has the ability to change the speed at which a video plays back. A user can use After Effects to raise or lower the number of frames per second, in effect altering the video playback speed, by using the time stretch function.
Start After Effects and import the video you wish to alter into your Timeline as a new layer. If necessary, follow the onscreen prompts to create a new project. The video will appear in the Preview window and in the Timeline at the bottom of the screen.
Select the clip you want to edit in the Timeframe by clicking on the desired layer's name. This will ensure that any changes you make will be applied to the correct clip.
Select the "Layer" menu to display the different effects that can be applied to an individual layer. It is located on the Main Menu bar at the top of the After Effects window.
Select "Time Stretch" under the "Layer" menu. This will bring up the "Time Stretch" dialog box.
Set the desired factor you wish the video's speed to be altered by. The "Time Stretch" window will have a percentage bar set at 100 percent, representing the current speed. The speed will change in relation to that percentage. To increase the speed increase the percentage. The dialog box also gives you the option to set the exact time you wish the clip to be.
Select the RAM preview option under the "Time Control" menu. This will allow you to view the changes to your clip.
Fine tune the speed higher or lower to achieve the desired speed up result. It may take several attempts to get the speed correctly set. Make sure not to increase the speed too high, or significant loss of quality could result.
The amount the speed a clip can be adjusted and the resulting quality are entirely dependent on the specific properties of the original clip. Clips that have been recorded at a higher quality will be more malleable. Ensure that the "Project" and "Video Import" settings are set correctly to help prevent a resulting loss in quality as this would make it more difficult to adjust the playback speed of a clip.