See no activity in video decode box.

This is with HEVC legacy decoding unchecked. Same result with it checked.

I believe that Vegas Pro is not utilizing GPU properly

At this point, I am out of ideas other than resetting your dynamic ram allocation back to default...that is way too high.

It would help you to set the Dynamic Ram preview back to the default of 5%

@VEGASDerek I would be interested to know why V20 does not use the 1080TI GPU to decode with this file when it can decode HEVC 4:2:0

No issues with Resolve

Just for information, I don't have an integrated GPU.

With VP20 I do not get any GPU decode even though it's turned on, with VP21 it uses the new decoder and it does decode.

You don't have any GPU decode with VP21b187 when you should with your P6000. I think that's like your 10 series GPU's eg gtx1070,1080. They should work fine

Quick update: I downloaded V21 trial on my new system.

With V20 it uses so4compoundplug.dll to decode, which uses the iGPU UHD 770 to decode but not the 1080Ti, all at Best/Full. The decode using IGPU is fluid at 60fps. The 1080ti is not used and frame rate is 2-4fps.

Now with V21 it uses mxhevcplug.dll which uses IGP UHD 770 (when set in File I/O), not as fluid as V20, frame rate drops to 45-53 in places and 60fps middle to end of clip, also there is some distortion in the last few seconds. V21 also uses the 1080ti when set and mxhevcplug.dll, offers the same performance as IGPU but without the distortion at the end of the video.

Maybe Vegas team can say why V20 uses so4compound plug in V20 and Mxhevcplug.dll in V21?

@andyrpsmith I think the performance difference you are seeing is because vp21 Intel decoding is high-quality, more like vp20 legacy-hevc. Vp21 is higher in performance with it's high-quality decoding, but not as high as vp20's Intel decoding without legacy-hevc checked off. Vp21's experimental-hevc decoding is more like vp20 without legacy-hevc with a similar quality tradeoff for better performance. If you use experimental, just keep in mind it might be more prone to crashing till they make it more bullet proof in future updates. Personally, I'd recommend cutting the project frame rate in half for smooth editing without experimental and restoring it for renders. My 2nd choice would be using Vegas proxies for editing with Preview-Full or Preview-Auto which automatically switches to the original when rendering or selecting Good or Best for previewing.

I'm surprised, btw, that your Nvidia 1080ti isn't decoding your hevc 4:2:0 60fps clip... the Nvidia decoding matrix says it should. Maybe the frame rate is what's throwing it. Or not using experimental. If you see other software playing it with Nvidia decoding showing up in Task Manager, that would suggest it's a Vegas issue that they might be able to do something about.

Thanks Howard, using experimental in V21 (so4compoundplug.dll) does not use 1080ti decoding while the legacy mxhevcplug.dll does, however in V20 the legacy mxhevcplug.dll does not.

@andyrpsmith

Quick update: I downloaded V21 trial on my new system.

With V20 it uses so4compoundplug.dll to decode, which uses the iGPU UHD 770 to decode but not the 1080Ti, all at Best/Full. The decode using IGPU is fluid at 60fps. The 1080ti is not used and frame rate is 2-4fps.

Now with V21 it uses mxhevcplug.dll which uses IGP UHD 770 (when set in File I/O), not as fluid as V20, frame rate drops to 45-53 in places and 60fps middle to end of clip, also there is some distortion in the last few seconds. V21 also uses the 1080ti when set and mxhevcplug.dll, offers the same performance as IGPU but without the distortion at the end of the video.

Maybe Vegas team can say why V20 uses so4compound plug in V20 and Mxhevcplug.dll in V21?

Official explanation

https://www.vegascreativesoftware.info/us/forum/vegas-21-update-omits-legacy-hevc-decoding-checkbox--143351/#ca896510

@andyrpsmith SO4 GPU decoder doesn't work correctly with many file formats for Nvidia decoder, nothing to do with your 1080ti the new GPU decoder version of mxhevc can't play more than one file at once so is broken.

Many thanks for the updated info about the decoder.

Luckily my media is Sony XAVCS which is of course Vegas friendly and decoded fine with both my IGPU and 1080tI (waiting to upgrade this but not for an £1800 RTX 4090 that may also burn out its connector), I may be tempted by the potential 4080 super in Q1 next year if it is around £1000 or less though.

@andyrpsmith I've noticed the new decoder uses a lot of Vram, but maybe it's like gaming where there is a difference between reserved and used Vram, and it's just reserving too much. Example a 5.3K GoPro clip uses 21GB Vram, SO4 uses 11GB, but is there any advantage at all in it using 21GB, is it going to play back better than someone with 8GB or 12GB GPU Vram, you'd like to hope not, and if not, I'd like my Vram back

16GB is a good amount of Vram, and both 4070ti super and 4080 super has that.

@Former user The new decoder uses a certain percentage of the available Vram on the assigned card. What's not needed for pure decoding is dedicated to cache already decoded frames. You should see the benefit if stepping backwards in your project or scrubbing.

So not all of your 21GB Vram used are used for pure decoding...