Cache - Am I missing something?

So our department has been evaluating Resolve, looking to move a portion of our editorial/graphics work from a Premiere/After Effects workflow to all Resolve 15. After figuring out a lot of production issues, the biggest roadblock now to greater adoption is that caching in Resolve 15 Beta4 just seems to be broken, or at best half-implemented. Maybe we are missing something (I hope!). Premiere Pro and After Effects have a lot of problems, but one thing they do right is caching media. It happens invisibly in the background, just "works" and does the job of improving responsiveness so an artist can get work done and preview edits or comps in realtime.

It's fine if Resolve/Fusion have a more hand-on caching system, as long as it works to increase responsiveness, which doesn't seem to be happening for us. The promise of sharing caches between users across the network looks good on paper, but we are finding it coming up short in practice.

Our setup:
iMac (2018)
64GB

or iMac Pro (2018)
128GB

2petabyte Fiber SAN
BlackMagic Ultrastudio Express or Decklink
All company media is encoded ProRes 422 or ProRes4444

What we expect:

• Manually trigger caching of a timeline/comp to either RAM or disk.
• System caches all required clips/compond clips/nodes/etc. Plays back in real-time.
• In Edit: If I then add/move things in the timeline it will ONLY re-render changed elements
• In Fusion: If I change a node, it only re-caches downstream nodes/changed media
• Cached media is persistant between sessions. If I close and re-open the app, media should still be cached.

What we are seeing:
In Edit
We see the following problems whether we are using smart or user caching.

• Resolve will re-cache the whole timeline with every change, whether adding or moving a clip or changing a property
• Caching happens automatically in Smart or User. Can't manually trigger or reserve CPU/GPU cycles for UI. When caching clips using Fusion, UI often freezes and can't continue working
• In user mode we see you can manually set the cache mode on each clip, but it still starts caching immediately, killing performance.
• Can't cache Compound Clips - This is huge as compound clips seem required to complete any edit or start a Fusion comp!
• It doesn't seem that disk caches are persistent. Close and restart the app and it has to re-cache everything.
• Really needs a "Render and replace" option to automatically render a clip, import it and replace it on the timeline, with the ability to edit the original.

In Fusion
I see you can set the cache on individual nodes by using "Cache to Disk", but it is unclear if it is just caching the "data" of that node or if it's caching the output of that node. It seems the intention is to "Cache to Disk" the last node before the MediaOut node and it "should" playback the comp in real time, which has not happened for us. At best, even on our iMac Pro, we get like 6-7fps on a heavy 3D comp, the timeline is green, so I assume that it has been cached. Not the case? Or are you supposed to cache every node to get it to work?

• Always seems to cache in .raw format. Assuming this is an uncompressed still format. Is this changeable?
• While I see you can manually set a cache name, it defaults to "DiskCache0000". Is the cache overwritten from Fusion comp to Fusion comp if they always use the same name?
• Media cached in the Fusion tab doesn't seem to carry over to the Edit or Color tabs.
• Cached comps not playing back in real time.

In general our editors find Resolve lacking, at least from a performance standpoint. While they see the advantages over Premere, especially those coming from Avid, once you start adding OFX or creating Compound or Fusion comps it just becomes unresponsive. Animators are finding this is also a pain to work in, espcially in graphic heavy composits. Without the ability to preview in real time, it's very hard to work.

The colorists still love it though!

Hoping that we we just missing something with the cache system or that better documentation is coming.

[Peter Chamberlain]

Hi Chad, thanks for feedback.

In the current beta, the Fusion page cache is not working fully, particularly disk cache. The edit page compound clip cacheing is not working in this build and we are looking into that regression. But some of your other issues seem to work for me.

I have render cache set to Smart.. and on the edit page i don't see the whole timeline cached let alone recaching everything. One those items needing cacheing are cached and when those are changed they recache. I can only imagine you have a clip that's across the whole timeline that you are moving causing a need for re-cache it all? If not, please take a phone video to show the issue.

I also just tested persistence of cache between project changes. Even exiting Resolve and restarting with a different project first, then the cached project and cache was persistent. Can you show a way to repo your issue?

The manual cache selection for an individual clip also works for me. When selected via 'Render Cache Fusion Output" "On' the clip(s) are marked for cache and i can still perform other actions, and when i pause, the cache is performed to disk. Steps to repo your issue will help.

I agree with our cache on, smart or user, the cache process runs as its not waiting for another user input to start, or pause. Resolve will cache clips when in playback if they are selected to cache, or when there are idle CPU/GPU cycles. Most users seem to not want another level of cache on/off but we can consider this again.

Hi Peter,

Thank you for the detailed reply.

Ok, I see where the problems are now, and I think it's mostly dealing with the Fusion integration. We tried out just a cuts-only project and the cache does work as advertised. We put a bunch of clips on a timeline, threw some OFX or color on them and it caches as expected in smart or user. Close and restart the app and the cache persists. Cache rendering automatically on unused cycles doesn't seem to affect general UI responsiveness as these effects render pretty fast. Adding new clips to the timeline and the cache works as advertised. Compound clips are obviously a problem, but shared cache between users seems to work.

I think all our issues revolve around the integration of Fusion. The workflow we are testing is Edit->Graphics->Edit->Color->Sound. So a rough cut is sent to graphics for compositing and titles, which is then sent back to edit for finishing then to the color department. Almost all of our test projects use Fusion to some extent. Ideally we'd like to use Resolve in place of/in addition to our current Premiere/After Effects workflow. It looks like all the cache issues I detailed have to deal with clips using Fusion. Cached clips keep re-rendering on the timeline and the cache does not seem to be persisting. But if that is a known issue, then I won't belabor it.

I'd be happy to send you any of our test projects if you PM me.

Other than the cache problems I am sold on moving away from Adobe to Resolve and have mostly convinced our 100+ department to move over once the beta is complete. Resolve is just a much more modern piece of software and solves a lot production issues we have been dealing with.

I have always found caching to be one of the trickier things to get to work in Davinci.

Some things that would make it easier for us:
- Compound clips seem to not be possible to cache. this feels like a big oversight. I blended 2 videos and put them into a compound clip, but how can I now get it to playback fast by using caching?
- I find there is no good indication of if a clip is cached or uses optimized media. Yes when you edit you can see this with the line above the clip, but how about in the color panel or in the Media panel? Also when I cache a node in the network, how can I tell if it is cached? I think the clips should have a little marker. Also in the edit you don't know what type of caching that was used, was the node cached, the whole clip, or? Small icons could solve this.
- If you marked a node in the network I wish that it would cache it right away or in the background. Now you have to go back to the beginning of the clip and wait for it to cache, then test to see if it was indeed cached.
- I wish caching could be done in the background like in Final Cut Pro X. Now you just have to sit and wait for a long time if you are using more complex sharpening or noise reduction.
- I wish default caching was not set to uncompressed, that will not playback very good on my machine anyway. I always use a form of DNxHR since it looks good and playbacks quite well but keep setting it up over and over again.
- Another thing I wish you could do regarding playback is just use a shortcut to switch debayer settings. For example between fullres and quarter res. Now I have to go into the menu that annoyingly also defaults to Arri, even though we only work with Red media.
- I have never got smart caching to work on nodes. If I have a heavy node like Neat Video it will be very slow and it will never be cached.
- I have no idea how to share the cached files with anyone else on the team. It doesn't help that they have nearly random names. I wish it used a similar naming and organisation to FCPX
1) Original 2) Optimized 3) Proxy
This means that it was very easy to copy the project to someone else. You can even go in an replace the proxy files with other types of codecs if you want to.

Maybe you can do some of these steps above, but these are some of the issues i have had with caching.
/Andreas

Hey everyone. I'd like to add to this that I cannot use temporal effects like noise reduction or motion blur on compound clips.
Is there a workaround that would not be pre-rendering the compound clip?

Hey everyone. I'd like to add to this that I cannot use temporal effects like noise reduction or motion blur on compound clips.
Is there a workaround that would not be pre-rendering the compound clip?

I don't think there is a work around. You have to render them out as far as I know.
Would be great if compound clips could be cached optimized since I would like to use them a lot.
/Andreas

buttons for cache?
all cache related commands grouped in a drop down menu? Why are they separated ?
all cache off button?
purge all cache ( disk, memory, gpu memory) button?
memory/gpu memory/disk counter?
I can check gpu use and memory through Msi Afterburner but it would like more pro if BMD adopt a cpu-gpu-memory resource counter.

regards

Hi, everyone. Beta 7 includes caching for compound clips yet no temporal effects. Am I correct?

I asked a fellow colorist using Resolve 14 and he told me noise reduction works normally on compound clips. Is this also correct? I am dreading having to roll back.

Fantastic that the new beta 7 has caching of compound clips. I have not been able to try it yet since we cannot multi install, but will test at work! Anyone tried?
Exciting!
Andreas

I camne to Resolve 2 years ago from Vegas Pro, so - unlike most of you guys - apart from random glitches here or there (like not keeping entire timeline cached between same project's sessions) I find caching working pretty well, actually. But my use of it is still limited to caching my color nodes - I have yet to learn Fusion to be able of assessing how its caching subsystem works. But I hope that - by the time I'm fluent enough in Fusion to actually need caching - it will be as good as Color nodes' caching is now, considering the tremendously fast pace BMD is developing the system

In Vegas Pro - where I needed a portion to playback realtime - I used caching to RAM, but even this is much less effective than DR's Color and Edit caching...

Piotr

Group cache does not seem to work well (or at all). In user cache mode, I have a group pre-clip with heavy OFX filters set with group cache on. However, any downstream tweaks made on regular clip color nodes or group post-clips, these wipe everything away, each time necessitating re-rendering from scratch. I'm on an iMac Pro and it is taking nearly a full day to render this two hour show. Now thanks to the upstream group cache simply not sticking around, every series of tweaks / update means I must then leave the show for a half-day to full day render each and every time.

Just want to second what worldpoop posted. I'm experiencing the same issue, with noise reduction on a node in Group Pre-Clip in user mode for the cache. Any changes downstream on the Clip page force the Pre-Clip noise reduction to re-render... I'm assuming this is a bug, unless I'm missing something?

Hello. I can not create a new topic. I have a problem with DRS 16, fusion cache rendering does not use GPU, only CPU. Cache color rendering uses GPU also final rendering uses GPU. Does somebody know how to solve my problem?