Sony Vegas 10 Slow rendering CPU / GPU rending tested

[Dave Haynie]

[Davd Keator] “Since you are now in the world of GPU rendering as well. If you are using the Sony AVC and have GPU engaged & your video card is a crappy old 9800 or something, you are wasting resources by your processor cores waiting for the GPU…”

Most of these things are easy to check. Given that the GPU is at best a slight improvement in performance, render without it, see what happens. If you have an i7, try it without hyperthreading. On the other hand, I don’t know of any of these actually slowing a system down that much. I use a six core AMD 1090T (3.2GHz) system, and I get pretty damn close to 100% CPU use, all six cores, with or without GPU rendering selected. My GPU is a nVidia 8800GT, nothing state of the art.

The one big exception to that is when the HDD starts to become a problem. While most assets don’t come close to the performance limits on an HDD, or so you’d think, when you have many assets on a single drive, you’ll start to thrash the disc — too many seeks to keep the drive going at peak, which ensures the CPU is always going to be waiting. That’s the one thing I’ve seen clobber performance to the extent you’re seeing. It’ll obviously be worse if you have larger video formats, eg, multiple Cineform or DNxHD will see this sooner than multiple AVCHD or MPEG-2, and of course, external drives are usually slower, versus internal.

RAIDs can also be slower, depending. A RAID is inherently slower on seeks — the seek occurs as the slowest of all drives involved. Single-steam, you never see this, because the virtual sectors are Nx as large. But if you’re doing smaller seeks (which is not so controllable in Vegas), you’ll hit that extra bottleneck.

I often use two or more drives for input on large projects, and usually render output to the C: drive or an external USB or Firewire drive, not something that’s hosting any assets.

[Davd Keator] “Through my experiences: 2 gigs per core are needed for vegas, 6 cores means 12 gigs…”

That’s a generally started rule of thumb for systems in general. But demands are actually much lower for a single program with multithreading versus multiple programs multi-processing. The difference is simple: in the multithreading case, each processor is likely to be running the same code. And by design — the inner rendering engine should be designed to run entirely from cache, L1 if possible, L2/L3 otherwise. Each thread will run the same code, that’s the bottleneck. As well, I suspect most of the Vegas rendering code was worked out some years ago — if you have a 6x processor, you have larger caches by far than they had in mind.

In terms of all memory used, I have 8GB on my 6 core system, and have never seen more than 6GB committed memory, running Vegas and, generally, several other programs. Not that memory’s too expensive to have more, but that’s certainly not the difference between 100% rendering and 20% rendering efficiency.

-Dave

[Jeremiah Brown]

I was going insane: a new machine i7 2600K 8GB RAM SSD SATA III . . . and MPEG-2 encoding was humming along at 20-25% cpu usage, taking 1hr20 for 1hr’s worth of video to encode! I read all these things “it only works with certain codecs”, bottlenecks lurking everywhere, disabled the pagefile, rendered to different drives etc etc.
It was the Dynamic RAM Preview amount of RAM assigned. I’d set it way up, I’d set it to the middle – didn’t do anything, I turned it off, that was even worse, like 18%, but it showed that it did SOMETHING.
So I went from 2048 over 1024, 512…16…8..4..2..1: I saw 95-100% finally! Now the video took 20 minutes to encode, and me is happy as a lark about the purchase. This is what I bought it for: save time and do things I could never do before.

Please, someone report back if it worked for them, too.

I would like to hear why something like Dynamic RAM Preview would do anything at all with the render/encoding process.

regards

[Jeremiah Brown]

I forgot to mention: When I had set Dynamic RAM Preview to significant amounts, at render start Vegas would go really fast using all the CPU power until it filled up all the dedicated RAM (like 2, 4, 7 GB)and then drop CPU usage to 20 and some, while it keep holding on to the RAM it seized. And Vegas didn’t even let go of the RAM after project termination. What gives?
Now that I set Dynamic RAM to 1, I am right now rendering a 1hr video sequence with three video filters active in 23 minutes at 97-100% CPU and 1,95 GB Memory usage constantly.

The term Dynamic RAM Preview to me suggests that this is solely about the timeline preview. But then the RAM amount assigned here is filled up during the render process, so here’s clearly an interaction between the switch and the render process.

Pray please, how is one supposed to figure this out when the terminology is so misleading?

[Dave Lozinski]

This is really interesting information to note. Thanks for the update and what you found was causing the problem!

Next time I render a large movie file, I’ll be curious to play with this now to see if it makes a difference because I have 16GB of memory in my machine, and I think I have the dynamic RAM set to 4GB of that.

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

You should not set Dynamic RAM Preview too high because whatever memory you allocate will not be available for use during rendering.

~jr

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

[Josh Bowren]

Want to add my two cents about Dynamic Ram Preview.

My computer will start to render fast then slow way down to a crawl and
I would get horrible bottle necking issues.

So I set the Dynamic Ram Preview to 0mb just before I rendered and whoa.

The computer will keep all the processors (4) at a constant rate the whole render time. Pretty good speed as well.

Vegas 10e 32bit AMD Quad 4gb Ram Windows 64bit 7 Home premium. Rendering 1920x1080i to MPEG2.

Of course I have Dynamic Ram at 1024mb when editing.

Give it a try.
josh

[Rob Wijnhoven]

My 20 cents.
Using Vegas 11, Core i7 2600k, 8 GByte and Windows 7 Professional.

Dynamic RAM: 0 MByte –> render time 3:00
Dynamic RAM: 1000 MByte –> render time 3:08
Dynamic RAM: 2000 MByte –> render time 3:08
Dynamic RAM: 4000 MByte –> CRASH
Dynamic RAM: 6000 MByte –> CRASH

Love to see the most unstable of Vegas Pro ever released 😉
But anyway, there is not much difference, perhaps they fixed some bugs.
Strangely, Vegas actually uses all the dynamic preview memory while rendering.
Although it does not seem to need it (at least for the system I have), and for most people it seems to work against performance…
Very strange!

[Dave Lozinski]

Thanks for that. Very interesting indeed. Glad to see I’m not the only one who has had issues with the Dynamic Ram preview.

As far as I’m concerned, I’m just using a RAM DISK now — faster than any other way to render or SSD. 🙂

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https://www.davelozinski.com
https://www.davelozinski.com/DemoReel/
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[Rob Wijnhoven]

Interesting. How do you use the ramdisk?
– To read the input video files
– To store the compressed output video
– Other?

I use an SSD to store the source material (and save the render), but the actual editing feeling is exactly similar to reading from a recent harddisk.

[Dave Lozinski]

[Rob Wijnhoven] “Interesting. How do you use the ramdisk?
– To read the input video files
– To store the compressed output video
– Other?”

All the above. Depends on the size of the project.

For other: I also have all my temporary rendered files stored there as well.

If the project is small enough (eg, all the source files and such take up less than 2 GB), I tend to copy everything (including the veg files) to the RAM disk, work on it there, and then when finished copy the veg file back to my hard disk (and any other source files which may have changed).

Now I always render to the RAM disk unless I know for certain the resulting output is going to be larger than my allotted RAM DISK (which doesn’t happen often).

It’s fantastic because it’s the fastest way to go, and there are no “drive bottlenecks”. It’s also exponentially faster than any current SSD/HD solution out there.

When I’m happy with the results, I copy the rendered video file(s) back to the hard disk.

I don’t have to worry about cleaning things up because when I turn off my laptop, the memory gets wiped. 🙂

If you have a machine with > 8GB of memory, I would definitely look into setting up a RAM Disk.

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https://www.davelozinski.com
https://www.davelozinski.com/DemoReel/
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