The truth about the Dynamic RAM Preview max setting

SilentNight wrote on 10/10/2021, 12:54 AM

I've been using Vegas for a long time now and I'd really like clarity regarding what this setting actually affects since there is plenty of conflicting information online. Some say set to 0%, others say max it, others say anything in-between to help with getting a smooth video preview.

When I was using VP18 it was crashing a ton and I contacted support and they said to set this setting to 0% which helped me crash less.

Now I heard many of the crashes were being caused because this setting was affecting things it shouldn't have and that this was finally fixed in VP19.

My question is assuming the bugs with this setting are fixed in VP19, does changing it do anything for standard playback at all or has it all been placebo? Based on the name of the setting, to me it sounds like it only affects the amount of RAM reserved for when you manually build a Dynamic RAM Preview with Shift + B. In which case wouldn't it be best to set the setting to 0% if you never use that feature so that the rest of Vegas can use all your RAM?

Or do I misunderstand Dynamic RAM Previews in Vegas? Does Vegas automatically build these during playback to help smooth things out? But then what would be the point of manually building one with Shift + B?

Comments

Grazie wrote on 10/10/2021, 1:22 AM

Lets get this out of the way first. Meaning of the word, Placebo:

A substance that has no therapeutic effect, used as a control in testing new drugs.

A measure designed merely to humour or placate someone.

Now, you’ve asked some pertinent, apposite and logical questions. I’ll give it my best shot..ahem…

VP uses a/the System to allow us to have the best FPS as possible. Mix into this a poorly conformed mix Media and the “wheels” start dropping off. Now add a dash of FXing and a sprinkling of Compositing and Noise Redux and we have, albeit, a well-meant Timeline and VegasPro attempting to deliver FPS a sluggish patient. Keeping it simple, does help to get good FPS. So far so good? OK. Now, take into account ALL the various mixed and muddled PCs and Laptops out there and you can see just what a smorgasbord of issues can arise, yes? So, wanting to at least get the Artist something that can offer-up decent FPS, Shift+B is there as a backstop to those times when the Artist needs something better. Now comes the understanding of the Balance between System usage of RAM being hobbled by the consumption of Shift+B, and that is a dark-art. Remember about ALL those different System Environments I mentioned? This Dark-Art is left to you and me to find a way through it. As you rightly suggest some people say X and some people say Y, yes it can be confusing, but placebo, it is not.

If you want a further discussion on the options to achieving better FPS, then we can do that. My starting discussion points would be:

1 - PreRendering: Shift+M

2 - Render to New Track.

3 - Happy Otter Scripts “Quick Preview”

You've asked some great direct questions. I hope I may have illuminated some areas for remedy. Again, not a Placebo 😀.

RogerS wrote on 10/10/2021, 1:29 AM

It appears to serve as a general preview buffer (try tests yourself with it on and off).

Forcing it to build a ram preview will ensure an entire section will be buffered before playback (assuming adequate amount of ram is assigned to dynamic ram preview) rather than just a few seconds that can be done on the fly.

After creating a preview, playing back elsewhere on the timeline will replace the preview if there isn't enough ram reserved for both.

Prerendering (shift-M) was revamped in VP 19 and is less transitory than ram previews so I started to use it more. I still have dynamic ram preview at 10% and not 0% now.

SilentNight wrote on 10/10/2021, 2:29 AM

Looks like I'll have to start using Shift + M again.

As for Dynamic RAM Preview max, I just verified that it does appear to be a general preview buffer using the task manager. I opened a project that had my overall system sitting at 16.4GB memory usage. Playing it back with Dynamic RAM Preview max set to 0% did not increase my overall RAM usage however setting it to 75% playback rapidly increased my RAM usage. We can determine a couple things from this.

The first is that VP tries to create Dynamic RAM Previews during regular playback to help with subsequent playbacks and Shift + B is just there to do this for large sections where you need smooth playback and don't want to spend time playing it back with choppy playback first.

The second is that setting this setting too high OR too low will have a negative impact on Vegas performance.

If you set it to 0% you get no benefit from this playback cache or if you set it lower than your system can handle you're missing out on some performance during playback.

If you set it to 75% of 32GB (what is in my system) and your project + Windows puts your system at 16.4GB RAM usage overall like mine this is bad as well as you will overshoot with continued playback. 75% of 32GB is 24GB. 24GB + 16.4GB is 40.4GB which is more RAM than the system has. To avoid crashing Windows will start paging to storage when your system is trying to use more memory than it has. When this setting inevitably causes Vegas to use more RAM than the system has my guess is that everything slows down as some stuff gets paged.

I'm not a Vegas developer but for this reason having the user set this setting seems like a poor idea. It seems like they need to add some math that runs every now and then to calculate how much RAM the user has available and just use the rest of that instead of having the user set a hard coded value like this. They should still have a slider so people that wish to can limit the Vegas memory usage by percentage, but it should be based on available RAM not max ram.

For now though the best way to set this slider in VP19 appears to be the following:

1. Open task manager and view total system memory usage.

2. Open your largest most intensive finished project in Vegas and any programs you might normally have open in the background, set Dynamic Ram Preview max to 0%, then playback some of the project until the total system memory usage stops fluctuating.

3. Subtract the total system memory usage from the amount of memory in the system.

4. Set the Dynamic RAM Preview max a bit lower than the remainder.

Musicvid wrote on 10/10/2021, 2:39 AM

@Grazie

Grazie wrote on 10/10/2021, 2:50 AM

@Musicvid - I’m glad you agree.

@SilentNight - Great work. I see you’ve become a Dark Knight 🥷 of the Dark Art 😎.

RogerS wrote on 10/10/2021, 2:51 AM

SilentNight, I think your observations are right.

I also think the developers should make dynamic ram preview truly dynamic (and limit user input) and it should take into account overhead of what other software is using (if that's possible- does the OS tell Vegas that?) so as not to negatively impact performance.

Grazie wrote on 10/10/2021, 3:18 AM

Whilst our Engineers are dealing daily with the machinations of getting a working platform together that also teases and entices newcomers and retains or improves the market share, actually to make profit rather, for shareholders and MAGIX.COM, it has to put aside Time=Money to make a connivance that would “craft” such a fandanglement that would make this ongoing audit of system resources? Presently, they don’t have the wherewithal to Birth a Text Editor, how are they going to do this SuperBrain that would do it? Don’t get me wrong, what’s being proposed is a magnificent concept, which has been touched on before now.

Who’d be an NLE Developer? 😉

fr0sty wrote on 10/10/2021, 6:29 AM

It would be nice to see DRP replaced with a background render/cache system similar to FCPX, where it's constantly working in the background while you are editing to feed RAM with pre-rendered frames to display. I know the team would like to implement such a system, but don't have any idea as to when they'd be able to do it.

Former user wrote on 10/10/2021, 8:07 AM

In a recent test I did with a particular 4K60fps file playback, I was getting 44fps with dynamic ram preview set to 0, and 60fps set to 50mb or higher, so it affects normal playback also. In that situation it really didn't matter, FPS with both was smooth enough for editing

3POINT wrote on 10/10/2021, 8:30 AM

Also setting DRP to 0% decreases dramatically the rendering speed. (at my PC 25-30% slower)

Former user wrote on 10/10/2021, 8:42 AM

The 25% slower you see in rendering matches the 25% less fps I got in playback