Improving Render times

jrappl wrote on 4/13/2015, 2:10 PM
Maybe this will help others. My setup is an i7-3770, 16GB, 2 SSDs. It performs well on almost any task. I've been video editing for 10+ years and a SMS user for 2+ years

I normally do simple projects - 1-2 video tracks, 1 audio with maybe a little background music, and a few titles, plain and rolling and mild video effects.

Preview has always been at full frame rate, render times decent with SD (MC mpeg DVDA templates) at about 1/2 of the timeline time and HD stuff (MC or Sony 720p) at 1.25-1.5 times timeline time. This using CPU only for renders.

My latest project is more complex - 4 video tracks, 3 audio, cropping and rotating, color correction, etc... My preview was lagging to 1-3 fps in spots!! Final render times were much higher than my previous projects.

I started searching the forums and internet for ways to improve it, tried almost everything and nothing really helped. Even using QSV with Sony AVC only provided a slight improvement over CPU only. I could not find where the bottleneck was. Monitoring showed the CPU running between 20-30%, GPU between 10-15%, memory only at 4-6GB used and disk access at only a few MB per sec. SMS was always "waiting" on a thread.

Just for kicks I went to preferences and changed "Maximum number of Rendering Threads" from 8 to 16. Boom, preview went to full frame rate and renders now get the CPU usage over 90%. The render times are now very similar to my less complex projects!

My CPU has 4 cores + hyperthreading for up to 8 threads active at a time. SMS was not able to keep the CPU busy when renders were confined to it using 8 threads!

So, if your render or preview is slow and your CPU usage is low, try bumping the number of threads!

Comments

musicvid10 wrote on 4/13/2015, 9:44 PM
Two forms of selective Prerender are available for your preview experience in Vegas. Read.
Expecting any system to keep up with realtime processing of that much timeline "stuff" -- some of it likely single threaded-- is a bit well, pollyanistic.
jrappl wrote on 4/14/2015, 8:37 AM
I'm aware of the the options for prerender. It's not an ideal solution. It takes the time to pre-render and any edits invalidate the prerender and it is lost.

I was also looking at 13 for the proxy edit as a solution but my point is - bumping the max number of rendering threads from the default of 8 to 16 solved my prerender lag (at least for this project) and improved my final render times drastically.
D7K wrote on 4/14/2015, 11:10 AM
I too have my threads set at 16, but make sure you have good cooling (running a temp read out while rendering) if you are pushing all your cores to close to 100%.
musicvid10 wrote on 4/14/2015, 9:02 PM
"It's not an ideal solution."
For those of us with less-endowed systems, it's a blessing.

jrappl wrote on 4/16/2015, 11:33 AM
No, you don't want to overheat or the CPU will slow defeating the purpose. It may shorten the CPU life also.

At build I upgraded to a large HS/Fan in place of the stock one, a BIO update also helped me as the older MSI BIOs was pushing higher voltage than required (but still in specs), new bios lowered voltage and lowered temps.