Using the Retiming Controls

The retiming controls have two common uses.

In all cases, if the source media file contains audio, the audio also has its speed changed, with the audio pitch corrected so that it sounds the same as the original, just at a different speed. This ensures that you will maintain sync between the video and audio.

If you preview a setting that uses retiming controls, the video will play at its new frame rate or speed, but it will not have been processed by Frame Controls and will be of a lower quality than the actual transcoded output file will be. The audio is pitch corrected when the setting is previewed.

Important: If you are using retiming controls on a setting using the QuickTime Movie output format and choose “Pass-through” for the audio setting, the audio does not have its speed changed and will not maintain sync with the video. See About the QuickTime Movie Encoder Pane for more information.

Converting Video to a New Speed

The retiming controls give you three options for determining the playback speed.

Figure. Retiming Control section including Rate Conversion pop-up menu and "Set Duration to" buttons.

You can determine the playback speed of the output media file by:

  • Entering a percentage

  • Entering a duration

  • Forcing the frames to play at the Encoder pane’s Frame Rate setting

Entering a Percentage

You have two options when using the percentage method to determine the clip’s duration:

  • Entering a percentage value

  • Choosing a preset value

The presets that you choose from are intended to be used for specific situations.

Figure. "Set Duration" presets pop-up menu.
  • 24 @ 25: Use this setting when you have 24 fps video that you want to convert to 25 fps for PAL distribution.
  • 23.98 @ 24: Use this setting when you have 23.98 fps video and want to convert it to 24 fps.
  • 23.98 @ 25: Use this setting when you have 23.98 fps video and want to convert it to 25 fps for PAL distribution.
  • 30 @ 29.97: Use this setting when you have 30 fps video and want to convert it to 29.97 fps.
  • 29.97 @ 30: Use this setting when you have 29.97 fps video and want to convert it to 30 fps.
  • 24 @ 23.98: Use this setting when you have 24 fps video and want to convert it to 23.98 fps for NTSC DVD distribution.

With all these options, no intermediate video frames are required—the existing frames are just set to play back faster or slower.

Entering a Duration

The duration field shows the clip’s current duration. As you change the duration, the percentage value changes to reflect that change.

This option is most useful when you have a source media file whose duration is a bit longer or shorter than it needs to be, and you’d rather change its playback speed than add or remove video frames.

With this method, intermediate video frames are created as needed.

Forcing Frames to Play at the Encoder Pane’s Frame Rate Setting

This option is used when your source media file uses a frame rate different from the Encoder pane’s Frame Rate setting.