Preview jerky with 32bit floating... active

blink3times wrote on 9/11/2007, 5:50 AM

I'm running a Q6600,ati 1950 video card and 4 gigs ram on vista 64.

Plenty of power, but I am still seeing some jerky preview movement when 32bit is active.

Comments

MH_Stevens wrote on 9/11/2007, 12:29 PM

The "Who's Whining" thread tells how 32 bit floating being active severely wrecks HDV playback. Seems it's a trade off. Having bad color or having good color and not being able to see it? Can someone explain just HOW much worse previewing is. I'm longing for a Vegas where you can preview HDV at anything other than "Preview Auto"

jrazz wrote on 9/11/2007, 12:34 PM

I raised this question here.

The short of the matter is I have a 5000+ AMD x2 proc, 2 gigs of fast ram and an EVGA nVidia GeForce 7950 GT 256 ddr3 video card. Not that I think anything matters save for the cpu.

With the above specs, I am getting 10fps on auto/preview when 32 bit float is activated. I get full frame rate on auto/preview and auto/good when 8 bit is set.

j razz

Cheesehole wrote on 9/11/2007, 8:27 PM

In 8-bit mode I've been getting 29.97fps with HDV at Best Full in V7/8 (with some CPU to spare).

If I switch to 32 bit it drops to 3fps. Switching the gamma to 2.222 makes it go up to 6fps for some reason.

GlennChan wrote on 9/11/2007, 9:35 PM

In 32-bit mode Vegas has to convert the values to 32-bit float, and then back to 8-bit int. On conversion to 8-bit int, it probably has to ensure that the values are in a 0-255 range to avoid over/underflow (so there's extra processing there). As well as overhead in converting between 32-bit float and 8-bit int, and the extra memory bandwidth that 32-bit values take.

In gamma of 1.000, there is an additional gamma corrected --> linear light --> gamma corrected conversion. That also slows things down.

Just my guess anyways. Anyways the bottom line is that the other modes are slower.

bruceo wrote on 9/11/2007, 9:57 PM

Sort of sucks that SCS would say 32 bit in the feature list, but fail to mention that you couln't preview it at more than 10-15FPS on a screamer. Sort of like when they were touting being the first NLE (V6)to edit HDV on machines with low resources when after the release it turned out that you had to offline/online edit with proxies that took days to render and still werent frame accurate

Cheesehole wrote on 9/11/2007, 10:14 PM

Thanks Glenn!

megabit wrote on 9/12/2007, 12:27 AM

After experimenting a lot (I am on a fast QX6700 and also witness a drop to some 3-4fps in Best/Full), I found the Draft(Full) to be the best compromise. One thing to remember is check "Scale video to fit the preview window", it then runs at the full 25.000 fps (my projects are 25p), with prewiew at exactly half the v/h res (i.e. 720x540). It's OK with the preview window, but of course still poor in full screen mode...