Slow render speed

[Cantisque]

Hello!

I'm having issues in VS21 with the speed of the renders. Even with no filters applied, GPU acceleration off, my CPU usage only hits about 50% utilization. Is there a setting somewhere I may have missed?

Profile:
MPEG-4 Files
24 bits, 2560 x 1440, 60 fps
Frame-based
H.264 High Profile Video: 60000 Kbps, 16:9
48000 Hz, 16 Bit, Stereo
MPEG AAC Audio: 128 Kbps

[tletter]

I'm having issues in VS21 with the speed of the renders. Even with no filters applied, GPU acceleration off, my CPU usage only hits about 50% utilization. Is there a setting somewhere I may have missed?

VS has never fully leveraged available CPU power but VS2021 at least partially utilizes a NVIDIA GPU (see following image). Hence not using the GPU is going to reduce rendering speed.

Is there a setting somewhere I may have missed?

1. Enable Hardware encode acceleration for NVIDIA CUDA.
2. Are you letting VS match the properties of your source video clips?
3. Have you tried setting the priority of vstudio.exe to Realtime?

tletter
https://www.youtube.com/user/tletter

[Cantisque]

Hi tletter.

CUDA results are awful. Everything has a blocky shimmer to it, even for scenes with no motion (I can share examples if it helps). If anyone knows a way to improve this I'd be grateful!
Setting vstudio.exe priority to realtime has no effect.
Using the project settings also gives a terrible result (but does hit the CPU harder, up to 85%). It sets the bitrate down to just 7000 even though the source is over 10 times that. I suspect the source is variable bitrate and VS doesn't understand it?

[Davidk]

If the hardware 'accel on' (CUDA) results are awful then turn it off. Corel has a history of hardware accel not working well. They made an effort to fix that and also use AMD a year ago, but it still has conniptions on some machines. Bear in mind that for CUDA to use the processor in a GPU to assist the main cpu, there's a lot of matches needed - the bus speed, your cpu clock rate, how much RAM memory you have, the various device drivers involved etc. But if it doesn't work, turn it off.

Your video specs give some indication that the results you are getting may be normal. For example, the resolution size cited is non-standard: more than FHD, but less the 4K, so VS is going to have to work at it for every frame. That realtime result indicates that: at that priority, the cpu isn't being diverted into other chores. I'm not really into H264, but the data rate also seems to be high. Put together, it's spec that's obviously tolerable - VS hasn't had a hissy fit on it - but it's enough out of the usual to require a lot of work in render. More work takes time.

You haven't indicated for the vsp duration what sort of render speed you are getting vs what you expected. Perhaps you could give those details. For an FHD or more project, rendering is going to take 2or more times the duration of the project to render. For the halfway house this seems to be, a time for a 4K render might be a better expectation. A good fast system spec might make it a bit faster, but there's a lot of work to do.

[Cantisque]

Hi David,

CUDA definitely renders faster (I'd say about 40-50% faster), it's just the picture gets mangled when exported.

Here are a couple of cropped comparisons. Both project settings are the same, except for one is CUDA and one isn't. Regardless of which export profile is chosen or custom profile made, the result is always the same, including between h.264 and h.265.




It's not a big deal to make do with CPU rendering, even if it's not making full use of it. I tried lowering the resolution and CPU utilization remained about the same. 4K exports did make the CPU work harder, though. Just a shame CUDA is broken.

[Vdanny]

Hi,
I have used CUDA rendering with multiple editing and effects programs and find it always produces an inferior render compared to CPU or Intel QSV. I don't think that Videostudio is broken as it seems to produce similar results.

[tletter]

CUDA results are awful. Everything has a blocky shimmer to it, even for scenes with no motion

My experience is that 4K H.264 videos rendered in VS with or w/o NVIDIA CUDA look identical wrt quality with near identical bitrate and file size. There is no appreciable difference in quality between the source clip and the rendered video.

Using the project settings also gives a terrible result ... It sets the bitrate down to just 7000 even though the source is over 10 times that.

VS2021 does appear to have a bug in that if you allow VS to match project's properties to the video clip properties (99,999Kbps - see LHS of image), then when rendering, the 'Same as Properties Settings' does NOT match the video clip's properties (see centre of image). However, the 'Same a First Video Clip' does work and sets the bitrate to 99,999Kbps (see RHS of image).

tletter
https://www.youtube.com/user/tletter

[rwernyei]

NVIDIA CUDA encoding is flawed and not NLE software specific. Same results can be observed using different NLEs.

As I wrote back in May:

"Vdanny is right. This is not a Corel issue. DaVinci Resolve Studio paid version takes full advantage of GPU Acceleration for H.264 and H.265 Decoding and Encoding. You can have up to 4 options based on hardware for encoding, Native, NVIDIA, AMD and Intel Quick Sync. I find Intel Quick Sync may not render faster than NVIDIA but definitely faster than Native and produces the sharpest picture quality among them all."

[tletter]

NVIDIA CUDA encoding is flawed

As a general statement this is flawed, since there are many HW and SW factors at play when using NVIDIA CUDA to render. However, your profile is completely mute about the hardware, OS and Corel software that you're using. This information is important to situate your comments.

Fortunately NVIDIA CUDA encoding works for me, and as previously stated, on my system running VS2021, "4K H.264 videos rendered in VS with or w/o NVIDIA CUDA look identical wrt quality with near identical bitrate and file size. There is no appreciable difference in quality between the source clip and the rendered video."

I'd suggest that any VS user with a NVIDIA GPU check the output quality when using NVIDIA CUDA encoding to see if it's OK. If not then using the latest drivers for NVIDIA may help.

tletter
https://www.youtube.com/user/tletter

[rwernyei]

Tletter,

Why are you always on the defensive? Other forum members have pointed out your flaws too. So I guess the term flawed in my post was too much for you. Regardless of my hardware/software specs others have experienced the same results. As we all know Corel has marketed for years as using GPU hardware acceleration but that is hardly true, more like a joke who has ever tried. I can name other NLEs that utilize GPU correctly but that might hurt your feelings even more. Again, you need to focus on the shortcomings of this mediocre product and not attack other members. Have a nice day.

[tletter]

rwernyei instead of trying to further the discussion, you simply engage in ad hominem attacks. I am sorry that you were triggered and had to lash out.

tletter
https://www.youtube.com/user/tletter

[TonyP]

In PCMag tests, VS has not been a fast render software as other software. And while other software can be more than twice as fast, it doesn't bother me much. I remember letting the computer render all night and hoping when I wake up, everything rendered correctly.
Could VS make "better" use of the powerful hardware that is out there? Of course. All software out there could do the same.
I'll have something to drink, or just let my brain decompress while rendering is happening, no matter what software I am using.

[rwernyei]

Well said TonyP.

After a couple saisons, the time would fly by in no time.

[rwernyei]

Tletter,

This post only applies to you since again you cannot help yourself. You strike me as a "have to get the last word kind of person". I did further the discussion clearly stating that both Corel and yourself suffer from shortcomings.

[Cantisque]

Just to clarify, this is definitely a VS issue and not a general CUDA one.

If I render in Premiere using hardware acceleration it's not only fast (with 100% gpu usage) but the blocky shimmering effect is gone.

It's definitely some sort of issue with VS and my current hardware or configuration, as it didn't used to be like this on my previous system. Again I refer you to the two example screencaps posted, these were the exact same project settings with no motion happening in the scene. Yes CUDA quality is not as good as CPU, but in VS specifically it gets absolutely mangled.