Rendering slows down after 2-3 minutes

johnfr wrote on 3/12/2010, 7:13 PM
I am experiencing a problem where my system begins to slow down as the rendering process proceeds. System configuration is i7 2.66GHz Gateway FX6800-01e system with 12GB of RAM ATI Radion HD 4850 video card, Seagate 1.5TB hard drives, Windows 7 Pro. When I first start a render my system is clicking off 10-20 frames a second. After 2-3 minutes is slows down to 3-4 frames per second and after 10 minutes or so of rendering it has slowed to less than 1 frame per second. I am rendering files captured from my Canon XH-A1 and or Canon HG-21 cameras. The recent work has been captured in HD and rendered in SD 720x480. I am suspect that something in the computers operating system and/or hardware is causing this slowdown. A 1 hour video will typically take from 2.5 to 3.5 hours to render.

I am wondering what render times others out there are experiencing and if anyone has experienced this slow down over time as the rendering process is running.

Comments

ushere wrote on 3/12/2010, 7:28 PM
have you any fx on the t/l?

is your opacity level constant?
Soniclight wrote on 3/12/2010, 9:37 PM
Yup, the moment the render starts chewing on anything other than straight video, it's going to slow down proportionally to the amount of muscle it takes to translate fx, keyframes, etc. So it's really impossible to compare render times, i.e. yours to that of others -- every project is different.

The only thing I can suggest is to clean up areas such as removing keyframes and fx that really aren't needed, as well as not using Composite or other Envelopes (especially ones that vary) unless absolutely necessary. While probably not an issue since render ignores them, probably good to remove empty or muted tracks and events too.

Other may have more/better suggestions.
Mikey QACTV7 wrote on 3/12/2010, 10:06 PM
I had a problem with dynamic RAM Preview set over 500MB would do a funky render slow down like your problem. If I set my Dynamic RAM Preview more than 500MB it would cause the render problems you have. I have 12GB of RAM on a i7. I also have the same problem on a computer I use with 64 GIGs RAM and 2 Quads. Check to see what your Dynamic RAM Preview is set at.
FrigidNDEditing wrote on 3/12/2010, 10:22 PM
If it's not FX..., it could be some sort of bandwidth slow down or system resources being consumed somehow? *IF* it's not some sort of compositing or FX that are causing a slow down.

Make sure all your clips and tracks are at full opacity and not turned down to 99% or something.

Dave
Grazie wrote on 3/12/2010, 11:05 PM
Start with some facts. Get to the render-test on this Forum and gauge just what you can expect from your setup. That will at least inform you as to what your PC is up to doing, compared to our colleagues here.

Grazie
farss wrote on 3/12/2010, 11:41 PM
Normally renders do start out very quickly because of RAM buffering anyway. It could well be nothing is wrong at all. 2.5 to 3.5 hours to render 1 hour of HD to SD is not bad, my system took 14 hours to render a 90 minute HD project to SD mpeg-2, not helped by doing a 2 pass encode.

Bob.
johnfr wrote on 3/15/2010, 9:41 PM
My thanks to Grazie for his help on this issue. On another forum he suggested that I try this same render test. When I ran the render test I had render times of 39-40 seconds which showed the computer was running reasonable speeds at least on short clips.

He also asked for some of my Vegas settings. He notice that the PAR settings for my project and render setting were not matched. One was set to 1.212 and the to .9. When I corrected these settings to both match at 1.212 the 50 minute video that had been taking 2 H 56 minutes to render was reduced to 41 minutes.

Lesson learned is, make sure these PAR settings are matched. ie that you are rendering in same mode as project settings.

Thanks Grazie.

johnfr