Why would a render take forever if one has plenty available resources?

[Tom Morton]

Lots of reasons:

Is AE using your built in GPU? This is very slow.

If you’re using CPU only effects in your project, and your CPU is throttled then this could cause it.

What rendering method have you chosen? Software only will only use CPU.

If you can’t work it out, tell us more about your project, and your setup.

[Xavier Bonet]

Hi, Tom, thanks for your reply.

I wish I could post a comp from it for you to check it out, but it’s part of an ad covered by an NDA. I can give you some technical details:
I’m exporting with 3D animations exported into 2 frame sequences: one EXR with multi-pass layers and one PNG with sketch lines. In AE I’m compositing them into several different layers to achieve a rough, hand-drawn look. That means, for instance, a layer for main colour, a layer for shadow colour, a layer for highlight colour, etc. Each layer has a pre-comp of a “grunge” animation as mask, to make it grittier. And some of the layers I’m blending using the dancing dissolve mode and bringing down the opacity a bit to make it grainy.

Because I need to make several “scenes”, I’m using expressions to link each value I might have to change to sliders and colour controls. And I have some expressions going on. But all in all, nothing too extreme. And indeed the playback isn’t too slow, even on “Full” resolution (which makes it more strange that the export takes forever and sometimes even freezes AME). I’m working it on “Half” and everything plays back fast and without any issues. (So I don’t think the expressions are causing havoc, as I’ve sometimes seen happen on really expression-heavy projects I’ve worked on.)

My project preferences in terms of Video Rendering and Effects is set to Mercury GPU Acceleration (CUDA), which is where I normally have it.

I’ve brought it down from 32- to 16-bits on AE, as on 32-bits AME would crash every time. And visually the difference on this project is very small, at least not enough to warrant the headaches!

I’m exporting on AME using hardware, not software. The renderer is set to Mercury Playback Engine GPU Acceleration (Cuda). The exported video is 1920×1080, 25fps, Progressive. Im exporting with Render at Maximum Depth and Use Maximum Render Quality checked. Right now, as a preview for the client, I’m exporting as H.264; but the final versions will be in ProRes.

Indeed, it’s using the built-in GPU, which I do expect to be slower, as you mention, but find it strange that only 10-20% of it is being used. Shouldn’t AE use 100% of it before it bottlenecks?

If there’s any other info that could be os use, please let me know.

[Xavier Bonet]

P.S. I’m talking about 10-second-long comps, that seem to speed through normally at the beginning, and later into the export they painfully crawl through each frame, making the total export time over 1hr long, if that. 🤔

[Walter Soyka]

Do you have Multiframe Rendering enabled (in Ae’s preferences, under Memory & Performance).

Do you have see a difference rendering in Ae with the Render Queue versus rendering in Media Encoder?

What does the new-ish Composition Profiler show you about the comp?
https://helpx.adobe.com/after-effects/using/composition-profiler.html

[Xavier Bonet]

Hey, Walter, thanks for your reply.

I do have Enable Multi-Frame Rendering checked, and have only 10% CPU reserved for other applications.

The difference between exporting in directly from AE and AME is negligible in this case. It unexplainably still gets stuck in the same places, while not using all my computer’s resources. What seems to be happening is that, as the export progresses, it starts becoming slower and slower, as if it were losing steam. This is what my last export attempt directly from AE looks like:

It shoots past the first 50 frames or so, the next 50 frames take about 2 mins, and from then on it really goes downhill, so that in the end, 250 frames (which is all I’m exporting in this case) renders out in about 40 mins to 1 hour. At around the 15 minute mark it’s at 80%; the remaining 20% is like watching paint dry, and it takes up the remaining 30-45 mins. (All the while, it shows there are plenty of resources available.)

If the comp had changes that warranted places where more processing power is needed toward the end, I would understand, but as it’s all made up of pre-rendered 3D animations working as masks for animated texture layers in AE, it should either all be easy to render, or all be difficult to render.

Finally, the Render Time column for the layer-heavy sub-comp mostly stays between 500-600ms, sometimes going down to 400ms, and up to 800ms. The other layers in my final comp are all between 0-30ms, and added up are less than 100ms.

[Xavier Bonet]

I’ve really simplified the comp. I’ve decided to solve most of the aesthetic needs in the 3D animation itself, so I’ve taken out most of the layers and masks in AE… But it’s still taking forever. I think that when I finish the urgent projects I have open right now I’m going to reinstall Adobe. I can’t think of anything else that might be causing this unnecessary bottlenecking.

[Walter Soyka]

Does it make a difference if you clear your disk cache?

I have a theory that Ae spends too much time managing the cache when it’s full or close to full, but I haven’t fully tested it.

[Xavier Bonet]

I also think that as the cache fills up AE starts to have problems. I haven’t seen that when exporting, but I have seen it many times while working on a project and in playback. Normally when it gets too wonky, I check the cache and it’s full or close to being full.

In this case, however, after the first issues, I cleared the cache and even moved stuff out of my export SSD just in case Ae was creating gigantic temp frames, and having issues with not enough memory (though I think it would be impossible to fill up over 500Gb with 250 frames 🤔). But all this to no avail.

What I haven’t tested is putting the rendered 3D frames in another SSD from the one I’m exporting in. Though I’m pretty sure this won’t do any difference, as there is really no difference in my workflow this time with every other time in the past, and I’ve never seen such bad performance.

That’s why I’m leaning toward corrupted software. I would re-install right now, but experience has taught me that doing any such thing in the middle of a project is like Russian roulette… So I’ll just suffer on for now, until I finish these projects I’m on, mid-December (if the clients don’t go crazy asking for a million changes 🤞).

[Xavier Bonet]

I’m thinking there is definitely something wrong with AE. I opened AE, just left it like that, didn’t open any project, and bit by bit it started taking up all of the RAM allotted to it, using up and around 96-97% of my RAM. Opening up Task Manager, there’s nothing else taking up much RAM, only AE. So, when exporting, even though my resource monitor says there’s plenty or RAM available, I’m assuming this may have something to do with it. Maybe AE maxes out the RAM and then stalls, which makes the RAM usage drop, but AE is already thrown into a crawl? 🤔

[Walter Soyka]

Very interesting! I’ll leave Ae running without a project open for a few hours over here and see what memory use is like.

What OS and what version of Ae are you running? I’d also be curious about third-party plugins & extensions you may have installed?