Image Caching

To ensure fast playback, Nuke uses several ways of caching data. Some of these include the following:

• The Viewer cache (also referred to as disk cache, which shares the DiskCache node's location) saves the scanlines of the displayed image to the disk cache directory. This location can be set in the Preferences panel (see The Cache Directory and Defining the Settings for Caching). When the Viewer displays an image, it reads from this cache of pre-rendered scanlines. This way, Nuke can quickly display image data when returning to a previously cached set of scanlines. You can specify the total amount of space for disk cache in Preferences > Performance > Caching > comp disk cache size . If the disk cache needs more space, the cache that was least recently used is disposed of to free more space. You can clear all of the disk cache by selecting Cache > Clear Disk Cache from the top menu bar.

Note:  Clearing the Viewer cache (disk cache) also clears the DiskCache node data.

• The Buffer cache stores scanline data as calculated at selected intermediate stages in the Node Graph. This speeds up the end result of the Node Graph by caching parts of the Node Graph that haven't changed. Nuke automatically determines these intermediate cache points based on several things, including the Node Graph structure, which properties panels are open, and so on.

Tip:  You can also force this behavior manually by selecting the cached checkbox in the node properties panel.

The Buffer cache uses RAM and you can specify the total amount of space in Preferences > Performance > Caching > comp cache size (%). When the buffer cache needs more space, it disposes of the first cached data that was stored (first in, first out). To clear all of the buffer cache you can either select Cache > Clear Buffers from the top menu bar, or press F12 on the keyboard.

• The Playback cache also helps improve smooth playback. Playback cache uses RAM to temporarily store the frames in the Viewer. When you first play back a clip in the Viewer, an orange bar appears automatically displaying the progress of the playback cache. After the playback cache is complete (and the orange line is complete) the frames play back smoothly. You can temporarily disable playback caching by either selecting the pause button above the Viewer or by pressing P. To clear playback cache select Cache > Clear Playback Cache.

• You can use the DiskCache node to cache parts of the Node Graph. This caches scanlines to disk from its input as they are requested by its output. DiskCache data is stored in the same place as the Viewer cache data and can share the data provided the Viewer is operating in full float (32-bit). See Using the DiskCache Node for more information.

Note:  You can clear all caches by selecting Cache > Clear All from the menu bar.

• If you find that loading files from a remote server slows down your processing, you can localize the files that you’re working with for speedier processing. See Localizing Files for Better Performance.