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Resolve 11: Taking Advantage of the Improved Render Cache

Tristan Kneschke

If you’re regularly experiencing dropped frames and sluggish performance, Resolve has a Render Cache feature that renders corrections for smoother playback.

For most Resolve systems utilizing modern graphics cards, real-time playback should be attainable (aside from intensive exceptions like playing Red footage at a high debayer).  However, in previous versions of Resolve, the Render Cache has never fully worked. It was the software’s glaringly broken feature, an anomaly in a package that worked so well otherwise. I found myself frustrated mid-session, quitting and re-opening the program to get the Cache to kick in. I assigned offending clips to the Cache manually, only to have the renders clear out, “get stuck” and not regenerate. Rendering was also often slow, with percentages ticking up at a crawl. When dealing with clients that expected a fast session, and at the least real-time playback, it wasn’t optimal.

Updated Render Cache in Resolve 11

That’s why I’m so happy to report that the Render Cache has been revamped for version 11. As with many of the software’s evolving features, Render Cache has been streamlined, simplified. We used to have Cache options for None, All, User, Dissolves, and User and Dissolves. Now, we have only three: None, User, and Smart. The Resolve team must have seen rendering dissolves as not very processor-intensive, and I’d seldom found a use for it in my work, usually opting to work in Unmix mode when on the Color page.

I’ve found the Smart setting to be most useful when utilizing noise reduction, one of the most processor-intensive tasks in the grading process. The Temporal Noise Reduction offered in Resolve has saved more than a few projects I’ve worked on, and the third-party OFX plugin Neat Video for Resolve is one of the best noise reduction tools out there. However, due to the intense processing involved, noise reduction is a memory hog that slows playback to a crawl. This is where the Cache comes in.

I just wanted the Render Cache to work as intended in previous versions, but Blackmagic has exceeded expectations. When processing, version 11 is intelligent enough to slow playback and renders just those nodes, similar to modern nonlinear editing systems. It saves time to ignore “simpler” nodes containing primary or secondary corrections that Resolve deems can be handled by the graphics card.

What’s more, Resolve will keep the rendered node intact while you’re working on the shot as long as you place further corrections after the rendered node. Let’s take a practical example. After applying the usual primary correction as the first node on a shot, you realize you’ve pumped the brightness too much and the shot is a bit noisy. Apply a layer of noise reduction on a second node and kick on the Smart Render Cache setting. Now, as long as you place supplementary corrections after the noise-reduced node, this second node will remain rendered, retaining your real-time playback (assuming you had it before). If you start making tweaks to serial nodes before the noise layer, Resolve needs to re-render the second node.

There is online discussion on whether to place the noise reduction earlier or later in the post production path. The same discussion could be considered as we go through the grading process. Resolve’s new Render Cache creates a case for the former, though one could just as easily scan through the project at the end of the session and apply noise reduction to shots that need it as a final step. It’s important to note that the effectiveness of the noise reduction can inform how a shot is graded, since presumably few would want digital noise in their pieces. Knowing the limitations of what is possible can prevent colorists from taking shots too far. Still, noise reduction combined with the improved version 11 Render Cache is an exciting development that is sure to lead to cleaner and more beautiful videos.

[Image from Blackmagic Design]