Apple Makes the Switch: iMac G5 vs. iMac Core Duo
by Anand Lal Shimpi on January 30, 2006 11:26 PM EST- Posted in
- Mac
iLife '06 Performance with iMovie HD
The next application that I looked at was iMovie HD, a part of the newly announced iLife '06. There are two primary focuses for performance in iMovie HD: video import speed (if you are dealing with a non-DV or non-iSight video source) and effect rendering speed. I focused on the latter, measuring the time that it takes to render various transitions and video effects in iMovie HD.
Note that all of the transitions and "Video FX" are single-threaded, so there was no performance difference on the iMac between running with two cores or one enabled.
First up are the transition rendering times. There are 15 transitions in iMovie HD that can be placed between two separate clips. I timed the amount of time that it took for the transition to be rendered upon inserting. Each transition was timed three times and the results were averaged - the average time is reported in the table below:
The Core Duo was slightly faster - the total for all of its transitions was about 8.5% lower than the iMac G5's time.
The bigger performance differences come when looking at the Video FX render times. These effects take anywhere from a few seconds, all the way up to multiple minutes to render, and can definitely bog down the creation of any movie project.
The sample above is almost all of the effects that you can perform in iMovie HD; the exception being all of the Quartz composer effects, which were left off in the interest of time. When the G5 and Core Duo are close, the G5 generally pulls ahead by a single digit percentage. However, when they aren't close, the Core Duo is usually ahead by at least 30%. If you average it all out, the performance advantage translates into about 11% in favor of the Core Duo. Once again, these tests are single-threaded, so there is no performance benefit due to the dual core nature of the Core Duo.
The next application that I looked at was iMovie HD, a part of the newly announced iLife '06. There are two primary focuses for performance in iMovie HD: video import speed (if you are dealing with a non-DV or non-iSight video source) and effect rendering speed. I focused on the latter, measuring the time that it takes to render various transitions and video effects in iMovie HD.
Note that all of the transitions and "Video FX" are single-threaded, so there was no performance difference on the iMac between running with two cores or one enabled.
First up are the transition rendering times. There are 15 transitions in iMovie HD that can be placed between two separate clips. I timed the amount of time that it took for the transition to be rendered upon inserting. Each transition was timed three times and the results were averaged - the average time is reported in the table below:
| iMovie HD Transition Rendering Performance in Seconds (Lower is Better) | iMac G5 1.9GHz | iMac Core Duo 1.83GHz |
| Billow | 5.36 | 4.14 |
| Circle Closing | 3.32 | 3.13 |
| Circle Opening | 3.41 | 3.09 |
| Cross Dissolve | 3.51 | 3.34 |
| Disintegrate | 6.14 | 4.73 |
| Fade In | 2.31 | 2.32 |
| Fade Out | 2.30 | 2.28 |
| Overlap | 3.25 | 3.25 |
| Push | 3.43 | 3.26 |
| Radial | 3.35 | 3.29 |
| Ripple | 6.74 | 5.32 |
| Scale Down | 3.73 | 3.53 |
| Warp Out | 3.58 | 3.91 |
| Wash In | 2.43 | 2.47 |
| Wash Out | 2.35 | 2.39 |
| Total | 55.21 | 50.47 |
The Core Duo was slightly faster - the total for all of its transitions was about 8.5% lower than the iMac G5's time.
The bigger performance differences come when looking at the Video FX render times. These effects take anywhere from a few seconds, all the way up to multiple minutes to render, and can definitely bog down the creation of any movie project.
| iMovie HD Video FX Rendering Performance in Seconds (Lower is Better) | iMac G5 1.9GHz | iMac Core Duo 1.83GHz |
| Adjust Colors | 75.62 | 48.62 |
| Aged Film | 30.43 | 32.44 |
| Black & White | 52.62 | 35.81 |
| Brightness & Contrast | 26.12 | 28.13 |
| Earthquake | 113.69 | 56.75 |
| Electricity | 78.47 | 54 |
| Fairy Dust | 151.69 | 58.63 |
| Fast/Slow/Reverse | 6.12 | 8.56 |
| Flash | 24.44 | 24.16 |
| Fog | 46.25 | 49.66 |
| Ghost Trails | 80.97 | 76.31 |
| Lens Flare | 61.12 | 46.22 |
| Letterbox | 26.94 | 28.75 |
| Mirror | 25.6 | 25.16 |
| N-Square | 31.13 | 32.63 |
| Rain | 45.6 | 39.75 |
| Sharpen | 35.75 | 43.25 |
The sample above is almost all of the effects that you can perform in iMovie HD; the exception being all of the Quartz composer effects, which were left off in the interest of time. When the G5 and Core Duo are close, the G5 generally pulls ahead by a single digit percentage. However, when they aren't close, the Core Duo is usually ahead by at least 30%. If you average it all out, the performance advantage translates into about 11% in favor of the Core Duo. Once again, these tests are single-threaded, so there is no performance benefit due to the dual core nature of the Core Duo.
Media Encoding Performance with iTunes and Quicktime
iLife '06 Performance with iPhoto, iDVD and iWeb
Facebook
Twitter
RSS
35 Comments
View All Comments
Anand Lal Shimpi - Tuesday, January 31, 2006 - link
Turning off one core leaves the full 2MB of cache for the other core to use since it is a shared L2.Take care,
Anand
Eug - Tuesday, January 31, 2006 - link
Cool thanks.
P.S. I have read elsewhere that the new iMac Core Duo uses less than half of the CPU's processing power to play back H.264 Hi-Def 1920x1080 video at a full 24 fps. If true, that's great, because my iMac 2.0 chokes on that. It plays back relatively smoothly, but only at about 12-15 fps.
That bodes well for a future single-core Yonah Mac mini.
Then again, probably not, considering that I suspect the iMac Core Duo does so well on H.264 playback because of its Radeon X1600. I'd doubt the Mac mini would get anything close to that any time soon.
Anand Lal Shimpi - Tuesday, January 31, 2006 - link
Max CPU utilization (across both CPUs) when playing a 1080p stream scaled to fit the screen is about 60%, but it usually hovers below 50%. I am not sure whether or not the X1600's H.264 decode acceleration is taken advantage of (I doubt it), I'm trying to find out now. Also remember that on the PC side, the X1600 will only accelerate up to 720p.Take care,
Anand
Anand Lal Shimpi - Tuesday, January 31, 2006 - link
I just confirmed with ATI, the X1600's H.264 decode acceleration is currently not supported under OS X. ATI is working with Apple on trying to get the support built in, but currently it isn't there.Take care,
Anand
Eug - Tuesday, January 31, 2006 - link
Thanks again for the info. That's actually good news in a way. Things are looking up for that single-core Yonah Mac mini HTPC.
andrep74 - Tuesday, January 31, 2006 - link
Isn't performance/Watt a function of the CPU, not the platform?Kyteland - Tuesday, January 31, 2006 - link
That picture of Jobs doesn't say "PC vs Intel" it says "PowerPC vs Intel". Jobs is just standing in the way. He's comparing the old mac to the new mac.Calin - Tuesday, January 31, 2006 - link
You could think about it that way - but in the end, the buyer is interested on the total energy consumption/heat production (as this is what he pays for, and what he must get rid of).Have you heard of the Toyota D4D engine? It has a record of 2.4 liter (less than a gallon) diesel fuel used per a hundred kilometers (60 miles). However, the same engine on a Land Cruiser 4x4 all options will get you much less (four times less maybe).
It doesn't worths talking about performance per watt at the processor level, it is better at the platform level.
BUBKA - Tuesday, January 31, 2006 - link
Were these benches done with a USB 2.0 device plugged in?Furen - Tuesday, January 31, 2006 - link
I was under the impression that Intel was blaming Microsoft for that, so that would not apply to OSX, though if the driver works perfectly for every platform except Napa I'd guess its a hardware problem that MS will fix in software (which is well enough as long as it works). The power consumption difference is probably less than 10W anyway. It matters on a notebook but hardly matters with a desktop.