V21 Z Depth in compositing mode brings playback down to 4fps

Mindmatter wrote on 2/23/2024, 5:21 AM

This was the initial post - read the solution in the answer.

Hi all

this is the weirdest thing ever, and I have no clue what's going on.

I opened a project that worked just fine yesterday. It's a 2 track 4k XAVCS-I 10bit 422 timeline, 2 audio tracks, with events having my usual FX, Colorfast2, color curves. I'm used to that combo slowing Vegas down some, so I mostly view things in draft mode or bypass some FX to have it run OK in preview mode.I recently added BCC beauty studio to do some skin softening, but deleted it until final render as it's recource heavy.

Today, I opened the project, and playback stutters at 4 fps even in DRAFT AUTO, then fluctuating up and down between 3 and 12 fps!

It's impossible to view properly.Even bypassing all FX. I'm on the latest Nvidia studio driver.

I didn't change a thing and totally clueless what to do now, as I'm in a slight panic mode deadline wise.

Any help is greatly appreciated.

Thanks!

Comments

Mindmatter wrote on 2/23/2024, 4:18 PM

I found the culprit - it's Z Depth, used at track level in the compositing mode.

I first copied some "problematic" events to a second instance of Vegas, where they played just fine.

Then, inside the actual project, I soloed the tracks one by one, and as soon as the Z Depth track was muted, things went back to normal. There's just one single event with a png on that track that uses Z Depth.

Expanding the track, I suddenly saw something very strange, look at this screenshot:

Z Depth created hundreds of keyframes, that seem to have completely hijacked the CPU. Why, I don't know.
But it's definitely a problem. I tried deleting those keyframes, it's only possible one by one. Then I hit " delete cache" inside Z depth, and they disappeared. But that didn't help, as soon as that FX is on, Vegas almost grinds to a halt.The mystery here is: why did it only start doing that after reopening the project the next day, while working fine in the other sessions?

fr0sty wrote on 2/23/2024, 7:59 PM

Yes, Z-Depth is an AI based effect, so it's going to slow things down, it requires a lot of processing power to pull off. You may do better by Pre-Rendering the scene that utilizes it into a new file (drag loop region over that scene, Tools>Render to new track), and then removing the original file that had z-depth applied to it. I'd render it to Prores 422, as it won't lose quality that way.

Mindmatter wrote on 2/24/2024, 4:01 AM

Thanks frOsty, it's what I'll end up doing. The FX actually uses like 52% of my memory while active.

I still wonder about a couple of things though - why did the slowing down not occur at first, only after I reopened the project the next day? And what about those keyframes...?