CPU Utilization Differences With Render Type

[John Rofrano]

[Mark Prebonich] “When I render to Sony AVC, the render time is significantly longer. This is not unexpected, however, the CPU usage is significantly lower averaging around 40%. Why is this occurring? And more importantly, how am I able to fully utilize the CPU in order to take care of this render type faster?”

You might try using the Custom button and on the Video tab change the Encode mode from Automatic (recommended) to Render using CPU only. Your GPU could actually be slowing down your render. I’ve changed all of mine to CPU only and Sony AVC renders significantly faster for me (and I have an NVIDIA Quadro 4000 graphics card!!!)

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Mark Prebonich]

John, I thank you for your reply. I was initially exited for the first 5 seconds where CPU utilization was at 70%. Then it went back to its usual 35-40%. Good thought though, but unfortunately to no avail. It would be nice if the Sony AVS render type would utilize the available CPU power. Any other thoughts? Thanks.

-Mark

[Dave Lozinski]

Something else to try that was reported in another thread I was reading (I don’t think it was on CreativeCow here)… reduce the amount of RAM you have for “Dynamic Ram Preview”.

Go to “Options”, then “Preferences”, and select the “Video” tab.

For kicks, put the RAM preview at something like 512 or 1024MB, restart Vegas, and see what happens when rendering out to the AVC with rendering options set to AUTOMATIC or GPU.

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https://www.davelozinski.com
https://www.davelozinski.com/DemoReel/
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[John Rofrano]

Also don’t forget that not all FX are multi-threaded. If you apply any FX that are single threaded, the render will never get above 25% on a quad core (because 4 x 25% = 100% of one core). So there may be some other reason that your project is not using all you cores.

If, however, you have no FX and are rendering to Sony AVC and don’t see all of your cores up around 80% – 90%, then something is wrong. I can easily hit 85% – 95% utilization on all 4 cores when I render to Sony AVC using CPU only.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Stephen Mann]

CPU usage is a really poor indicator of your computer’s efficiency. In fact, it’s worthless. A high CPU usage only means that you need a faster processor because the one you are using is struggling to keep up. A low CPU usage could indicate a lot of things, like some I/O bottleneck, or as John pointed out, a single-thread CODEC in a multi-core PC.

Steve Mann
MannMade Digital Video
http://www.mmdv.com

[Mark Prebonich]

My dynamic preview is set at 350 MB which is default. I do not have any FX in the project. With CPU only, it is still hanging around 35-40%. My CPU is a QX9770, top of the line a couple of years ago. I suspect I should just take what I get for now. I will be curious to see how things change after my next computer build.

[Dave Haynie]

The CPU use percentage is an extremely good indication of your system and project tuning, simply because that’s the one bottleneck you can’t get past. Sure, you may be stuck with a single-threaded plud-in, but that’s [a] rare, [b] possible to replace with a better one, and [c] easy to discover… by using the CPU performance monitor. You bottleneck could be hard disc (usually due to seek times coupled with too many high bitrate intermediate files on the same HDD), but at worst, shuffling assets to another HDD or two, and in particular your output, solves that problem. As John suggested, it could even be the GPU, but that is also easily fixed.

Any way, if the CPU isn’t over 90-95% during a render, you have a bottleneck that is probably easy to fix, though it can take some trial and error. I’m on six cores, and I can always keep the CPU as the weakest link. And doing so is the bottom line.. if you’re at 50% CPU, the render will take twuce as long… at least until the GPU becomes a useful bottleneck.

-Dave