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Keyframe Display in the Time Ruler
When you select a node with keyframed parameters, those keyframes appear in the Time Ruler as little white tic marks, letting you navigate among and edit keyframes without having to open the Keyframes Editor or Spline Editor to see them.
The Time Ruler displaying keyframe marks
— Press Option-Left Bracket ([) to jump to the next keyframe to the left.
— Press Option-Right Bracket (]) to jump to the next keyframe to the right.
The Fusion RAM Cache for Playback
When assembling a node tree, all image processing operations are rendered live to display the final result in the viewers. However, as each frame is rendered, and especially as you initiate playback forward or backward, these images are automatically stored to a RAM cache as they’re processed so you can replay those frames in real time. The actual frame rate achieved during playback is displayed in the Status bar at the bottom of the Fusion window during playback. Of course, when you play beyond the cached area of the Time Ruler, uncached frames need to be rendered before being added to the cache.
Priority is given to caching nodes that are currently being displayed, based on which nodes are loaded to which viewers. However, other nodes may also be cached, depending on available memory and on how processor-intensive those nodes happen to be, among other factors.
Memory Limits of the RAM Cache
There is a single setting in DaVinci Resolve for limiting the RAM used for caching. This setting is located in the DaVinci Resolve Preferences Memory and GPU panel.
— Limit Fusion Memory Cache To: This slider sets the maximum amount of RAM that Fusion can access for caching. It is a subset of the RAM allocated to DaVinci Resolve. You can assign a maximum of 75% to Fusion from DaVinci Resolve’s total RAM allocation. When not using the Fusion page, the RAM is released for other pages in DaVinci Resolve.
There are two settings in Fusion Studio for limiting the RAM used for caching. These settings are located in the Preferences Memory panel.
— Limit Caching To: This slider sets the maximum amount of RAM used for caching. The 60% default setting on a 32-GB system limits the cache to 19.2 GB. The maximum amount you can assign to Fusion Studio is limited to 80% of the total system memory. This leaves a minimum amount of memory for other applications and the operating system.
— Leave at least # MBytes: This number field further limits caching in cases where the system’s available free RAM drops below the entered value. For instance, setting this to 200 MB attempts to keep 200 MB of RAM free for the OS or other applications. Setting the number field to 0 allows Fusion Studio to use the full amount of RAM specified by the Limit Caching To setting, ignoring other apps.
When the size of the cache reaches the Fusion Caching/Memory Limits setting found in the Memory panel of the Preferences, then lower-priority cache frames are automatically discarded to make room for new caching. You can keep track of the RAM cache usage via a percentage indicator on the far right of the Status bar at the bottom of the Fusion window.
Displaying Cached Frames
All cached frames for the currently viewed node are indicated by a green line at the bottom of the Time Ruler. Any green section of the Time Ruler should play back in real time.
The green lines indicate frames that have been cached for playback.
Temporarily Preserving the Cache When Changing Quality or Proxy Settings
If you toggle the composition’s quality settings or proxy options, the cache is not immediately discarded. The green line instead turns red to let you know the cache is being preserved and can be used again when you go back to the original level of quality or disable proxy mode. However, if you play through those frames at the new quality or proxy settings, this preserved cache is overwritten with a new cache at the current quality or proxy setting.
A red line indicates that cached frames from a different quality or proxy setting are being preserved.
There’s one exception to this, however. When you cache frames at the High Quality setting, and you then turn off High Quality, the green frames won’t turn red. Instead, the High Quality cached frames are used even though the HiQ setting has been disabled.