Extremely Slow Export Times - Low CPU Usage?

[karsenb]

Hi everyone,

With my most recent project, I've been having some pretty long render times for a video that is only 1:24 in length. The last render took around 15 minutes, I've been trying different things to see if I could lower the time it takes.

The video is UHD 4K (3840x2160), from the Panasonic GH5. It's only 8-Bit footage as 10-Bit tends to be hard to playback natively from the GH5.

There is some color grading, and dynamic links from after effects that are done, but nothing to extensive.

So far I've tried rendering out to H.264, and DNxHQ. It seems that the time it took to render is about the same, even though smart rendering was enabled with DNxHQ.

My biggest concern is that both my CPU & GPU's usage haven't really been that high during the encoding process. During the export from AME, the highest I saw was 96% from my GPU, and the highest from my CPU was around 40%, which is quite odd.

Typically I get faster render times with AME since it uses the GPU for rendering. I tried to use Premiere Pro, but after 20 minutes I stopped the export and changed over to AME. - The usage was around the same, though it was only utilizing the GPU instead of the CPU.

Though here is what I found funny, I exported to DNxHQ 4K, and then re-exported that to 1080P H.264, and the usage SHOT WAY up on both ends. So that is something I definitely don't get.

Here are my computer specs:

9900K

GTX 1080

64GB Corsair Vengence 3200Mhz

SSD - OS (NVMe)

SSD - CACHE (SATA)

SSD - MEDIA (External, and tested with an internal NVMe, render times stayed the same.)

If there is anything else someone could recommend for me, please let me know, as this is quite odd to me and normally my PC has had extremely quick render times.

[MyerPj]

Sounds about right.

When you scale your footage in the export (4K->1080p) your graphics processor will really kick in.

Here's a screen shot of my Task Manager with both the GPU and CPU at 100% when making 4K->1080p proxies. It works really well, and my folder of 720p cineform proxies takes up less space then my 4K h.264 files.

PP 2019 - Making Proxies - Runs Well wTask Manager

[karsenb]

I think you may have misunderstood what I was saying.

When I render the 4K project in either Premiere Pro or AME, both my CPU & GPU usage are VERY LOW, and it takes 10-15 minutes to export an extremely small video.

I mentioned that when I would re-export the 4K video to 1080P, both my CPU & GPU usages were VERY HIGH, and it took less than 1 1/2 minutes.

I am trying to figure out why in the heck this video that is less than 2 minutes took such a long time to export in the first place.

[RjL190365]

If you are not resizing or applying any GPU effects, then your CPU usage should be very high but your GPU usage should be zero. Unfortunately, both CPU and GPU usage are very low, which means that there is something else in your PC, such as OS optimization and tuning (or lack thereof), that's bottlenecking it. And even your 4k to 1080p exports use 100% GPU but very little CPU even though both components are fairly high end - which also points to a bottleneck somewhere else in your PC.

[karsenb]

Well... actually there are CPU & GPU related effects.

There is one shot that has about 4-5 small masks that are tracking on a clip, which is all 4K footage, along with a nice color-grade, and text. But that doesn't even seem like much, but what I think I will do next is render out the After Effects portions of the video, then export from either AME or Premiere Pro and see if it's faster.

Also, I can say, there isn't a single bottleneck in my system as far as hardware goes, I can promise that. Multiple NVMe SSDs, so no issues from my hard drives, my CPU & GPU are powerful and not overheating. So I really think it's software bound.

[basil1891 · Accepted solution]

I believe this is the reason:

karsenb  wrote

... and dynamic links from after effects ...

Try to remove all AE-dynamic links, then export and check the CPU/GPU utilization.

[karsenb]

I will definitely try that and see what happens next. But, maybe I will just need to render out the AE dynamic links then render out the timeline.

[karsenb]

Instead of removing them, I render / replaced them, and that fixed the export times. Its now under 2 minutes, around 1:45 instead of 15 minutes. So the problem is solved, not sure why it only uses a single core and under utilizes it, which is nuts but I am glad to see that the problem is now fixed!

[RjL190365]

Basil has a point. Dynamic links from After Effects are only single-threaded to begin with. That, in turn, will prevent the other threads from ever coming close to becoming fully utilized.

[karsenb]

You say that the links are only single threaded? Is there an article that shows for that, that's quite interesting and I'd love to read about it.