Blackmagic Forum

I'm trying to render a project in Resolve Studio 17 beta 7 but I keep getting the following error:


It seems to happen in the same place every time, at a transition between two clips with denoising although I don’t know if that’s relevant. It happens both with H.264 and DNxHR HQ. I'm running a GTX 970 graphics card which I know is on the slow side for 4K but I thought this wouldn't be an issue when rendering. For editing and color grading, it works fine with proxies.

I exported the diagnostics log: https://www.dropbox.com/s/dz4maes612rxq ... 2.zip?dl=0

Any ideas why this is happening?

I have now verified that disabling noise reduction allows me to successfully render. But I need the denoising and I wouldn't expect it to just fail during rendering, it should just be slower, shouldn't it?

I tried disabling the option "Stop renders when a frame or clip cannot be processed" and now I get "Your GPU memory is full" errors instead of Render Fail errors. Does this mean that you need tons of VRAM not only to run with decent performance but also to be able to even render AT ALL? I always thought you could work around it with proxies and whatnot, and then simply let the render take the time it needs?

I need help to understand how this works, it feels completely opaque to me right now.

My thinking is that the GPU gets slower the more work you ask it to do, but you always has to have enough VRAM to keep in memory every frame it needs to be working on.

Noise Reduction and de-flicker are examples of effects that both need many frames (depending on settings) to compare and do their work.

When the two clips overlay in a transition you suddenly ask your GPU to do twice the work and it also need to have all the necessary frames from both clips in VRAM to do its work doubling the need for VRAM. My guess is that your GPU don't have enough VRAM to do this.

Possible solutions:
1) Render each clip for themselves and finish with a new project where you edit the finished clips together. I have used this solution on multicam clips overtaxing my system with de-noise etc.
2) Never tried but think I have read about the possibility to add an effects track over the clips and add effects like de-noise to that. Would that solve the problem? Is it possible?

Happy to be corrected if my thoughts on this is wrong.

oilar123 wrote:My thinking is that the GPU gets slower the more work you ask it to do, but you always has to have enough VRAM to keep in memory every frame it needs to be working on.

Noise Reduction and de-flicker are examples of effects that both need many frames (depending on settings) to compare and do their work.

When the two clips overlay in a transition you suddenly ask your GPU to do twice the work and it also need to have all the necessary frames from both clips in VRAM to do its work doubling the need for VRAM. My guess is that your GPU don't have enough VRAM to do this.

Possible solutions:
1) Render each clip for themselves and finish with a new project where you edit the finished clips together. I have used this solution on multicam clips overtaxing my system with de-noise etc.
2) Never tried but think I have read about the possibility to add an effects track over the clips and add effects like de-noise to that. Would that solve the problem? Is it possible?

Happy to be corrected if my thoughts on this is wrong.

I think you might be right that this is how it's actually implemented because that would indeed explain things. However, there's nothing that prevents you from implementing it in another way. For example, in a transition you don't have to process two frames at the same time, you can process one after the other and then blend them as a separate step. It will be slower but at least you will not run out of VRAM.

I'm just not used to running into these kinds of "hard" limits with software, at least not ones that are this high. Most software can fall back to CPU rendering or similar strategies.

Is this officially documented somewhere? That it's not even possible to render if you have too little VRAM?

render node caches set to mastering quailty
and then export using caches

Dermot Shane wrote:render node caches set to mastering quailty
and then export using caches

Ran out of memory this way too. Might be because I put my denoising in a group pre-clip and then it wants to cache the whole pre-clip graph which is still too heavy.

Aw well, I can just buy a new graphics card. Oh wait... I CAN'T becuase they don't stock them anywhere in the world!

I suspect a long standing bug in Resolve with regard to memory management using nVidia GPU's.

You don't specify your NR settings, but if you're using Temporal try reducing the number of frames.

Jim Simon wrote:I suspect a long standing bug in Resolve with regard to memory management using nVidia GPU's.

You don't specify your NR settings, but if you're using Temporal try reducing the number of frames.

I think I was simply out of VRAM. GTX 970 is probably not enough for 4K with any meaningful processing. I now have a 2080 Ti that I bought used and all my problems are fixed.

Until you try 8K, that is