Setting QuickTime compression optionsChoices you make in the Compression Settings dialog box require trade-offs between file size and movie quality. The higher the visual quality of your movie, the larger the file size. Quality The Quality control specifies the spatial compression of the movie, which compresses the data in each frame of a composition. Higher quality produces better image quality but results in a bigger movie file. Lower quality results in a blocky and slightly blurred image (although it is still recognizable) and a smaller, more compressed movie file. Note that this quality is unrelated to each layer's quality setting in After Effects. Key Frame Every In QuickTime terminology, the term key frames is different from the change-over-time keyframes placed in the After Effects Timeline window. In QuickTime, key frames are frames that occur at regular intervals in the movie. During compression they are stored as complete frames. Each intermediate frame that separates them is compared to the previous frame, and only changed data is stored. This greatly reduces movie size. Shorter intervals between key frames enable faster seeking and reverse playback but can significantly increase the size of the file. To specify QuickTime compression settings:
Note: Set the color depth in the Compression Settings dialog box instead of in the Output Module Settings dialog box. This ensures that non-Adobe plug-ins receive color depth information from After Effects. See step 8. Note (Mac OS Only): If you intend to use key frames in the movie, hold down Option and adjust the Quality slider to control the temporal compression of the movie. Temporal compression compresses a movie by comparing successive frames and keeping only changed data. High temporal quality maintains smoothness of motion. Low temporal quality tends to produce jerkiness of motion because a pixel doesn't change unless the difference between frames is great. Note: If you are going to use the resulting movie in another After Effects composition, type a small value (less than 5) in the Key Frame Every box or deselect the Key Frame Every option. The presence of key frames greatly increases the memory required to edit and render a movie. Note: Color depth settings of Thousands of Colors or lower may cause banding and dithered images. |