Random slow rendering times

brian-d wrote on 2/25/2023, 8:04 PM

I have Vegas 18. Just a few days ago, I rendered a 4GB video in 20 minutes. Was going about 60-75fps for it's average speed. Now, I'm trying to render a 1GB video of the same project settings. After 30 minutes it had only gotten to 75%. Considerably different speeds.

 

It's weird. It starts at about 2.5 FPS render speed for the first few minutes and then slowly ticks up to about 25-30fps average. Prior to this, it would reach it's average speed of 60-75fps in a matter of ten to fifteen seconds. At least from my POV, there should be no reason for a 1GB video to render considerably longer than a 4GB video. Anything I can do to fix this? Thank you

Comments

fr0sty wrote on 2/25/2023, 8:41 PM

Some codecs decode easier, some encode easier... So for instance, I can take 8 bit 4K video from my S1 and it decodes smoothly in real time without proxies, and renders extremely fast. If I up that to 10 bit 4:2:2, things change, I need proxies for smooth playback and rendering slows down a lot. Effects used also have a big effect on render speeds... generated media, 3D track motion, resolution or framerate conversion, image effects, especially AI effects, these all slow down renders.

Your best bet to keep things quick is to stick to 8 bit codecs, avoid HEVC (it decodes slower than AVC) if you can, if you need higher quality, shoot to ProRes if you can (they sell external recorders you can use to do that if you cam doesn't support it), and be mindful of the performance hit any effects you add will have to the final render.

brian-d wrote on 2/25/2023, 10:13 PM

Thanks. What's weird is that the 4GB video was a 25 minute video project that held many different effects and transitions.

 

The 1.88GB Video is a 13 minute video which features barely any edits. It's basically just a still image with audio. Thank you I'll check my settings!

RogerS wrote on 2/26/2023, 10:59 PM

It's not really ever random. Zooming into high res still images, upscaling, adding sharpening, other things that don't seem significant can require significant processing time.

Feel free to share version of Vegas, project properties and preferences/video and preferences/ file io settings for more guidance.

Only other variable is if the computer is poorly cooled it could overheat and throttle during renders depending on CPU and GPU load.