Good information. I wish SCS would further enlighten us on this. There must be more than meets the eye on setting RAM preview. I would assume it is somewhat specific to the PC. How about creating a RAM preview tuning tool that would feature three relative value meters:

1. Preview length
2. Render speed
3. Stability

And have a slider for RAM preview amount. As you move the slider the meters would adjust their relative value specific to that PC.

There has been pretty steady discussion and speculation about RAM preview for the last 10 or so years on this forum. SCS, please give us some insight.

/jerry

I strongly suspect that if SCS was able to add that tuning feature, that would mean they would also have figured out exactly what was going on with the Preview RAM problems and would then simply fix them instead.

The fact that there are problems means that the knowledge to create such a tuning tool doesn't yet exist, and if the knowledge existed the tool would be unnecessary.

The way I see RAM preview is like a buffer. Depending on your hardware and applications/services running in the background there is a golden mark. If set it too low, your time line playback or render process will cash up with it and if too high it takes too much time to fill the buffer hence putting too much strain on the system rather then helping. As mentioned earlier, hardware, running applications and background services vary on everyones system making it difficult to determine the correct amount of preview ram. Maybe SCS could run a background service constantly checking the load on system memory, GPU, CPU and other hardware involved in doing preview or rendering and then select the correct amount of preview ram but such a background service would take resources too. I did my own testing and ended up where default is set, 200MB and I believe that SCS did at least some testing and ended up with that figure too as a compromise.

Agree about the buffer. From documentation we know that RAM is used for Shift+B RAM rendering. We also know the RAM is preallocated when the application starts.

It seems obvious that Vegas uses that RAM for some other things, disk buffers or whatever, if the RAM has not been used for a RAM render. This is good in a sense, as why waste precious RAM.

This would also means that RAM rendering a section large enough to use all the render RAM would effectively be the same as a zero RAM setting for all those other accessory undocumented uses of that RAM buffer.

One can speculate on all kinds of uses but that is a worthless endevor.

As for stability regarding GPU and a zero setting. The GPU issues I have documented for Sony are of the hang variety. Basically some threads in Vegas were in a race condition and locked each other out on some synchronization resource. Race conditions are timing related, and changing RAM availability/use or your CPU clock slightly, or backround tasks Vegas relkated or not can make something go from stable to unstable with an identical input source (you project).

The question is about Preview RAM AND Max number of rendering threads together.

For the last couple of years some users here have tried several combinations of these 2 settings every time a new Vegas version or upgrade was released - and found what gives the fastest rendering times.
There are several long threads about this topic.

Often there was a speed peak around 75 MB Preview RAM plus some 4,5 or 6 Maximum number of threads.

Right now I have a peak for my Vegas 11 build 700 around some 22 MB RAM plus 7 max threads - where i.e. 6 threads increases the rendering time by some astonishing 15 percent.

If you start the Windows Task Manager you can easily see what happens: The CPU usage is much higher around the best RAM plus Max threads combination. Here I can bring my 2 x quad Xeons up to about 98 percent.

The fastest settings depend on your hardware, media, FXs used and output format, of course.

I do not use GPU acceleration as it is slower than CPU alone.

>It seems obvious that Vegas uses that RAM for some other things, disk buffers or whatever, if the RAM has not been used for a RAM render. This is good in a sense, as

Well, I have 16GB of RAM and still can't increase preview RAM above 200MB and be stable. This seems counter-intuitive to me.

/jerry

I have the same issues and increasing the RAM above 200 only causes more instability. I have Win 7 Pro on a I7 3930k 3.2GHz running with 32GB memory. Set at 200 P-RAM, I roughly use 32% of my CPU and that's with GPU turned off. When GPU is turned on, the program will completely self destruct, red screen, lock up, crash etc. when rendering tons of stills with video. I have a Nvidia GTX570 and for me the GPU acceleration does not work; never works at any setting(s). Also when rendering to DVD, the default settings are strange. The help states that the buffer size should be set to "232", yet it defaults to "23", so you will need to change this when making a widescreen dvd project.
Here is the program in its default state:
https://docs.google.com/file/d/0B6OOPg3t5JTbUG96LWl0bVN1bE0/edit?usp=sharing
Here is a screen shot of the help file:
https://docs.google.com/file/d/0B6OOPg3t5JTbZlRRLU8tcTNSSGc/edit?usp=sharing
When rendering hundreds of pictures with some video (ex. Cross Country Season for the High School) I will turn off RAM completely, lower CPU threads to 10, turn off GPU, check video buffer size, then start the render and leave for work (takes hours). All of the kids get a DVD.
This year, I plan on going back to my older XP Pro machine and doing this XC project in Move Studio HD Platinum. It handles thousands of pictures and video without any glitches what so ever. Does it faster, imports the pictures nicer, allows for the same transition's and pans and does all of this without and issues. I also max out CPU and finish in less time. Costs less too!

The only problems I have had with instability and GPU are with stills slideshow. In this case CPU only is totally stable, and RAM render setting makes no diff. Video files only I have thus far been okay with GPU.

I agree about Movie Studio and stills having tons better performance. Who knows why since they share a code base. I started in Movie Studio 12 and it handled my GoPro 12MP files fine. Vegas 12 stutters badly on these. I need to resize to 4MP for Vegas which is fine for 99% of my crops.

You can move to MS12 for a heavy stills project. The UI features and plug-in capability will be similar to Vegas 12 if that means anything to you.