late 2013 13 vs 15 rMBP and iMovie

[mrderik]

Greetings -

I just wanted to give a comparative analysis of the speed difference in the two new rMBP models under 'normal' everyday use. I looked at all the Benchmark stuff and disk write, blah blah blah but they never say what you can expect. So I just bought a 15" for work and a new 13" personally. I put a movie together, copied to both and rendered. Here's my results -

Both machines - Late 2013 rMBP 8GB Ram, 256GB, iMovie 10.0.2
15" is the i7 2.0 Quad Core. (Stock $1999 machine)
13" is the i5 2.4 Dual Core. (Stock $1499 machine)
(Both were also plugged in during transcoding)

Movie CONTENT source is about 32GB of 1080p, and a few dozen pictures in iPhoto, along with a ton of transitions.
Final movie is 35 minutes, 3.19 GB final size in 720p and 5.28GB final size in 1080p.

Here's the time to transcode to an MP4 file for the two machines and two resolutions -

15" 1080p 15 minutes
13" 1080p 20 minutes

15" 720p 19 minutes
13" 720p 27 minutes

What I found interesting, is that when USING the 13" and putting the movie together, I didn't find it much slower than the 15". Both moved clips around, and copied, with VERY few beachballs.

I guess I was expected the 15" (Quad core) to be much faster and it was at transcoding. 30-40% But in everyday use, both are lighting quick at startup, restart from sleep, numbers, etc. And that's compared to the machine i replaced - 2010 13" MBA.

Both machines in transcoding did have the fan come on about half way through the 720p movie, the 15" sounded louder, but both relatively quiet. And both never got above slightly warm to the touch.

So I guess, if I could only buy one, I wouldn't hesitate to get the 13". It transports easily, and I find the 15" a beast to carry around. But again, I'm used to the old 13" MBA. The screen on the 15" does seem WAY bigger though. Just that extra 2" I think makes a huge difference. So for the extra $500, the 15" is probably a better deal for power users. But for everyday use and transporting, there is NOTHING wrong with the 13". I love it. That will be my primary machine, period. I'd only use the 15" if I had big projects to crunch.

Hope this helps.

D.

 

[Groovemaster17]

Very nice comparison! Thanks.

 

[kathyricks]

Would the 4GB ram 128 SSD version of the 13" rMBP transcode those movies as fast as your 8GB/256 version did?
Or would it be considerably slower because Mavericks uses practically all of that 4GB of ram?

 

[maflynn]

Would the 4GB ram 128 SSD version of the 13" rMBP transcode those movies as fast as your 8GB/256 version did?
Or would it be considerably slower because Mavericks uses practically all of that 4GB of ram?

It appears the speed differences is probably a result of the CPU more then ram. Mavericks is very efficient when it comes to ram, but you'd need to view the page outs/swap space usage to see if the 4GB is part of the cause.

 

[mrderik]

Greetings -

I would agree with maflynn, to some degree. I just restarted a transcode to 720p, with the activity window open showing Memory on the 15". Total memory used varies during the process, but averages about 4.6Gb as the process starts, through about the first third, as follows -
2.06 GB App
1.46 GB File Cache
1.00 GB Wired

But the longer it transcodes, the higher the amount of memory used seems to creep. Which kind of makes sense especially on the file cache. Half way through, it's averaging about 6.5 GB total memory used -

3.13 GB APP
2.16 GB File Cache
1.01 GB Wired

And in the last quarter it's averaging 7.1 GB total used.

2.65 GB APP
3.50 GB File Cache
1.00 GB Wired

On the activity window, CPU usage, it shows iMovie fluctuating in CPU % throughout. It never seems to go below about 67%, and jumps occasionally to 150-212%.

So I can't help but think, the longer the project you're rendering, the more RAM is going to be beneficial. But this is purely speculative based on the observations above.

<edit> That being said, the "time" shown for the process to finish at the very start is somewhat accurate - when it's (only) using 4GB - ie, the process doesn't seem to "speed up" based solely on the increase in RAM being used. The processor (CPU) activity is a constant fluctuation, in a specific range, through the whole process. Which probably indicates, more RAM is not really speeding up the processing, it may speed up disk writes a little with a greater cache size, but this isn't having a significant impact on the actually transcoding.

D.

 

[esskay]

Thanks for sharing your benchmarks. Would be really interesting to see a current model MBA13 to compare as well... I wonder how much slower that would be?

 

[am2am]

Here are my tests:

1. late 2013 rMBP 15" 2,3GHz i7/16GB/512/ Nvidia 750M
2. late 2013 rMBP 15" 2,3GHz i7/16GB/512/ IrisPro (forced by gfxCardStatus)
3. late 2013 rMBP 13" 2,4Ghz i5/8GB/256/ Iris

Short movie with transitions (1m41s) export from iMovie 10.0.2 into file (mov -> mp4 1920x1080)

1. 31s
2. 51s
3. 1m20s