Odd Preview RAM behavior when at 0

Cheesehole wrote on 5/22/2007, 10:59 AM
As many have discovered, setting your preview RAM (Options | Preferences | Video) to anything significant like 256 or above will eventually result in severe deterioration of your preview frame rate to the point where it crawls along in the single digits. Only setting the preview to a different mode will clear the RAM cache and allow the preview to be fast for a while until it fills up again and slows to a crawl. That has prompted me to set the preview to 0. The preview framerate is definitely fastest when Video RAM is set to 0.

But when rendering to MainConcept MPEG-2 Vegas only utilizes one processor (25% on my Quad6600). So I have to bump up my Video RAM to 32 and it will use 100%.

It's kind of annoying that Vegas doesn't automatically adjust that at render time. So now I leave it at 32MB but I wonder if someone knows a better workaround...

Comments

rmack350 wrote on 5/22/2007, 3:44 PM
As far I know Vegas will use any frames that are cached in RAM for the render. It's interesting to hear that Vegas must have cached frames available in order to use multiple processors.

Even with a 1GB system, I'm surprised that preview performance grinds to a halt with just 256MB dedicated for the cache. I've not seen it, but maybe this has to do with the media you're using.

One thing to keep in mind is that the more memory you give to Vegas the more other applications have to be written to the swap file. If the system is kept busy reading and writing to the swap file it'll slow down Vegas, even if Vegas itself isn't being swapped.

It'd be nice to have tool to monitor Vegas's cached memory usage, with a slider to adjust it and a button to purge it. One more thing to fiddle with, though.

Rob Mack

Cheesehole wrote on 5/23/2007, 12:30 AM
No you're right at 256MB it doesn't get that slow but for HDV it's gets significantly below 29.97 whereas if I leave it down at 32MB or below the needle is buried at 29.97 fps.

I think you're right we just need a control... like easy access to that setting or an on/off/clear switch that I can put on the toolbar.

Ben