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2 Renders Faster Than 1??
Well, almost. Hi everyone. I’ve been using Vegas for about a year, mainly long, simple projects – analog tape captures to DVD, but I do a bit of videography as well, mainly school plays using 2 cameras. My day job is IT Technician, I’m fairly amateur as far as video goes.
I recently upgraded from an E4600 dual-core to a purpose-built Q9550 quad (both mildly OC’d) with basically the same 5-disk system (see profile).
My query is this: has anyone come across the following performance problem and if so did you find out why it happens and/or solve it?
With my old system the CPU was maxed out during rendering (from DV to DVD MPEG2), unsurprisingly, and I was hoping to halve the rendering time with the new CPU. But the new CPU isn’t maxed out, it only averages about 55% doing a single render (evenly spread between cores). Disk-bound? Nope, if I render 2 videos simultaneously it virtually doubles the throughput, CPU about 90+%, elapsed render time only goes up slightly and I can still happily edit another video (except for choppy/unusable external preview) in a third instance of Vegas without much impact on the rendering.
I expected and would prefer the system to be maxed out when rendering just one video, so it would finish sooner – current speed is around real time, typically 3hrs for full VHS transfers (much faster without the edge mask I normally use). I work around it when I can by rendering 4 simultaneously overnight, takes 6-7hrs, ie slightly more than double a single render.
Incidentally, second question, is there a better (ie faster-rendering) way of neatly chopping off the ragged analog edges than compositing a black 8px frame (and without rescaling the picture using pan/crop)?
Any help would be much appreciated.
PS
I bought DSE’s ‘Vegas Pro 8 Editing Workshop’ before I bought Vegas and was using the trials of Vegas and Studio – it helped me decide, and I haven’t regretted either investment!Rupert Stocks
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3 Replies
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This is pretty surprising. When rendering to MPEG2 I usually have all 4 cores blazing. Some codecs are not multi-threaded and won’t use all of your cores but the MainConcept MPEG2 codec usually takes advantage of everything you’ve got.
Which MPEG2 template are you using? Does it include audio? I’m wondering if the video-only template uses all 4 cores but the video+audio just uses 2? (one for each stream as it interleaves them)
~jr
http://www.johnrofrano.com
http://www.vasst.com -
When you upgraded did you re-install Vegas or simply run the existing Vegas on an upgraded system? I ask because you *MAY* have to reset “max number of threads used” to 4 (from 2)on an existing copy of Vegas.
The other thing to keep in mind is that number of cores being used and cpu usage greatly depends on what exactly you’re rendering.
As for all 4 cores running at a total of 55%…. Your OS can (and does) spread that work somewhat evenly over 4 cores if less than 4 cores are being used. Your OS will deliver a single core program for example over all 4 cores to a total of 25%…. unless of course the program specifically demands a single core usage… then you would see one core at 100% and the other 3 idle.
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Hi John, thanks for your reply.
[John Rofrano] “This is pretty surprising.”
Yes, that’s what I thought.
[John Rofrano] “Which MPEG2 template are you using? Does it include audio?”
‘MainConcept DVD Architect PAL’ / PAL WS, with or without custom bitrates (I created a set with different bitrates to suit different lengths up to 185mins). I do the Audio separately with ‘Dolby Digital AC-3 Pro’ Stereo DVD @ 192 or 224kbps.
Rupert Stocks
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