Yes, my CPU has an iGPU, but it isn’t used by Vegas. Should I disable it in the BIOS as well?

I don't think the iGPU is the problem as I don't believe the Ryzen iGPU can decode 422 either. But good to be clear about the test conditions.

The problem remains with iGPU disabled in BIOS as well

For "me", I downloaded the file and played it back on my computer spec'ed in my Signature below. Preview was set to Best>Full.

I didn't notice the "jump" that was shown in the video. Again, playback was smooth with not dropped frames or "jumping". But I am using an AMD GPU.

I also downloaded the file and played it back at best/Full with no jumping or dropped frames. I am using RTX 4080 super GPU. I have rolled back the Nvidia driver to 581 as 591 caused issues with V22 and other programs that deal with LED lighting not to work/load.

@Andreas-T I feel your pain, I have been notifying the developers of this decoding bug in VP23 for quite some time already. I have an RTX 5090 and it has 2 decoders vs 1 decoder (of the same new generation as yours). I have the same issue. Interesting to see that a HW single decoder 5xxx series GPU also has the issue, this confirms that it is not an issue of having 2 decoders as I initially thought a while back as the root cause.
I have been narrowing things down trying to find a workaround or the culprit so they can fix this.
Currently there are two workarounds that work depending on the source video.
I mainly work with pretty standard stuff out of my Sony RX10 camera (XAVC 4K in a 25P project (4.2.0 - 8 bit)) and enabling the legacy AVC decoding works perfectly without out of order frames (as it does use the so4compound OK). It seems that it does not work for your source video types.
The second workaround is a bid dodgy and certainly annoying to use (I'll explain further), but may suite your needs with your different source clip type.
You keep the legacy AVC decoding default (so disabled), try to live with the occasional out of order frames (the back and forth effect) when editing, then when you are done and want to render, close Vegas, launch Vegas again and do not touch, nor edit the timeline, and only start your render.
It seems the issue is linked somehow to timeline editing/ buffering in the new core engine or pipelines in VP23, and perhaps the combination with a 5xxx series GPU makes the issue appear more often...

@Andreas-T I forgot a third workaround that may (or may not) work for you. You mentioned trying to disable GPU HW decoding and this did not work, same here, but with Legacy AVC encoding disabled and using the combination

• HW decoding is disabled (none) + Dynamic RAM preview max is set to 0 (zero)

it may just do the trick (albeit you loose decoding speed...)

Make sure you get out of Vegas and relaunch again if you do any of these changes.

@bitman

Thanks for the help. The second and third workarounds both work fine, although they’re difficult to follow in everyday work. I do a lot of pre-renders of stabilized and slow-motion footage with MagicYUV, so I know that at some point I’ll forget to close and reopen Vegas,not to mention that this issue also affects Mercalli stabilization, and with the third workaround I do indeed lose speed.

Still, it’s good to know these options. A week ago, when I first noticed the problem, I had to move the entire project from 23 back to 22 and lost some time. With these tricks, I might have avoided that.

From what I understand, this is something that affects only the Nvidia 50xx series. That’s a shame, since I recently switched from AMD to Nvidia to improve my workflow, as I was having other issues with AMD.

It also doesn’t seem to be related to 4:2:2 10-bit as I initially thought, since you use 4:2:0 8-bit and encounter the same behavior. Maybe it has something to do with AVC? I’ll try switching my camera settings to 4:2:0 10-bit HEVC in the next few days and see if the problem persists.

I really hope the developers fix this soon, now that they’ve been informed by you.

One thing I see with a RTX 4060 mobile, GPU decoding on, is black frames just before the end of the media. I don't see that in my media player.

Now I see out of order frames in two places; didn't even try it with my 5070 yet, I'm seeing problems with the 4060 mobile.

I’ll try switching my camera settings to 4:2:0 10-bit HEVC in the next few days and see if the problem persists.

@Andreas-T I've been doing multicam using 4k hevc 4:2:0 10bit for years with Zcam & Canon cameras with great success. I too just finished pulling my Amd & Intel gpus in favor of newer Nvidias and they work better than ever doing hevc with vp23 using default settings. I think the key to my success is staying away from 4:2:2 and funky formats like xavc, 10bit avc, or long-gop. My typical 2- to 3-hour concert projects use three 4k hevc cameras and one or two hd avc/ptz. I set the Canons to 4k 10bit hevc mp4 and the Zcam to 4k 10bit hevc mov or mp4. Lately I've been upscaling the ptz to 4k 8bit 4:2:0 avc before bringing it into a multicam project and it's footage has fit in wonderfully... but hope to upgrade to 4k hevc ptz next year. Just updated my latest machine configs in my signature.

@Howard-Vigorita I hope I get the same results with HEVC; I’m going to test it early next week. Unfortunately, I was forced to use 4:2:2 AVC because the Lumix GH6 and GH7 both offer AVC at 4:2:2 with an acceptable bitrate, while the 4:2:0 AVC option only provides a 28K bitrate. I avoided using 4:2:0 HEVC because Vegas didn’t handle HEVC well until the last update of version 21. But now I need to change again because version 23 doesn’t like 4:2:2.

I’ve used HEVC in Vegas 22, but it consumed all the GPU’s VRAM, and GPU-powered add-ons like Neat Video (which I upgraded to version 6 because it was much faster than 5) became slow again due to the lack of available VRAM, forcing them to rely on the CPU. Is that still the case in version 23?

@RogerS

One thing I see with a RTX 4060 mobile, GPU decoding on, is black frames just before the end of the media. I don't see that in my media player

I used to see black frames at the end of clips when I was using an AMD GPU and MP4 files in Vegas 22. After I replaced both the GPU and the MP4 files with MOV, as someone here in the forum suggested, the issue disappeared.

Now I see out of order frames in two places; didn't even try it with my 5070 yet, I'm seeing problems with the 4060 mobile

So the problem is present with the 4060 Mobile as well, as I understand it, and it’s not only an issue with the 50xx series.

When I tested the clip again (same 4060 mobile) I got out of order frames elsewhere so it's likely a regression affecting various NVIDIA GPUs. We had a lot of issues like this late in VP 21 and early 22 but I thought they were solved.