Mac Pro - Best config for HB

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Posts: 11
Joined: Fri Sep 05, 2008 2:20 am

Mac Pro - Best config for HB

Post by kryten2001 »

Hi Guys -

I'm considering a purchase of a Mac pro, and I was wondering what you guys out there were using - and what configs work best.

Is the 8 core an advantage over the 4 core? Does HB make use of these extra cores, or am I better off going for a faster 4 core?

Also, what sort of encode FPS rates are you guys seeing with the latest incarnation of the Mac Pros? Is it significantly faster than I'm getting with my current generation iMac (2.67Ghz).

Thanks guys. Really appreciate any input you can provide.

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Re: Mac Pro - Best config for HB

Post by hunterk »

I can't provide any specific fps figures, but I know x264 scales up nearly linearly to approximately 16 cores, so you will see a definite, noticeable improvement with 8 cores vs 4 cores. Higher clockspeed will help too, obviously.

It will also definitely be faster than your iMac due to the increased number of cores.

Posts: 11
Joined: Fri Sep 05, 2008 2:20 am

Re: Mac Pro - Best config for HB

Post by kryten2001 »

Hi Guys -

Well for posterity, and interest for anybody else searching in the future, I've just bought and received my Mac Pro and thought I'd post some frame rate info up here. It's a little lower than I'd hoped for, but still very quick. I suspect the reason is down to the encoder (H.264) not using the full capability of the machine. When you profile the CPU(s) they only get to 60% utilised..

Oh well I guess the upside is I can encode and still have monster CPU in reserve..

Anyway the config is as follows:

Mac Pro -
8 core Nahalem @ 2.93Ghz
1TB "Black" WD Drive (From apple)
Dual 24" LED Screens
Twin Superdrives

I'm using the following config in HB..

Codec: H.264
2 Pass encoding
Default Decombing
2 audio tracks (Stereo + AC3 passthrough)
Deblocking set to -2,-2

This config gets between 120 and 150 FPS..

Nice eh.... That's at 60% CPU usage. Machine still flies.

Anyway just in case anybody else in the future comes asking the same question, there you go......

Come on HB guys, let's see a h.264 codec that can be programmed/scaled to use all the power of this machine, or even better - one that can be configged to use a max configurable % of all CPU...

Posts: 48
Joined: Tue Jun 03, 2008 11:09 am

Re: Mac Pro - Best config for HB

Post by ccjensen »

I am sure I have read that if you want to use 100% of all CPU's, your best bet is to start one transcoding PER CPU, ie 8 cores = 8 simultaneous handbrake processes running.
Congrats on the beast of a machine :)

Posts: 72
Joined: Tue Nov 04, 2008 2:35 am

Re: Mac Pro - Best config for HB

Post by KonaBlend »

For performance evaluation purposes, try the same encode with:

1a. decomb=off (and any other filters) -- I've seen this chew up 18% of throughput on 8-core Penryn w/ DV interlaced source.
1b. copy source media to hdd before test to rule out optical media bottleneck
2. after trying (1a+1b), tweak x264 threading parameters (this only effects x264 threads) by going to advanced tab, and appending to x264 Advanced Option String the exact text --> :threads=16

iirc, x264 should be using threads=24 (1.5 times number of "virtual cores" which in your case is 16. To verify if this setting is in effect, try threads=1 . once verified, play around, 8,12,16,20,24,28,32 . I'd be interested to hear your results.

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Re: Mac Pro - Best config for HB

Post by jbrjake »

Were you even checking the CPU utilization during the 2nd pass?

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