5 Replies Latest reply on Dec 21, 2010 4:31 PM by ECBowen

    i7 27" iMac or Mac Pro for avchd to BD and web?

    gerbow Level 1

      Some background firstly: I currently have a Mac Pro dual xeon 2.0 Ghz 1st generation Intel Mac. I am ready to upgrade and mainly use FCP although I cross-graded to PPro CS4 (Mac) from my old copy of Premiere 6 (Win) to be able to use Encore CS4 for producing BD; which I am very happy with. I have tried PPro for native editing of avchd and it is a non-starter; jerky playback at preview for 1080 50i clips. I now have another camera: panasonic SD-700 and have been filming using the 1080 50p setting.


      I searched for benchmarking info on the internet and whilst I know that the 6 core Westmere would be ideal, it is beyond my budget. I can stretch to a Mac Pro 2.8GHz 2010 with the standard ATi 5770 but will upgrade ram to 12 gb (kingston or crucial not apple!) and add three 1TB drives as a raid. The benchmarking data threw up some interesting info though - the 27" iMac with the i7 2.93GHz processor outperforms (in cpu terms) the base Mac Pro; admittedly not by much, but it is also cheaper.


      I could not find specific video benchmark data so I assembled some clips with transitions on the PPro CS4 timeline (1 single stream of avchd 1080 50i) and tested it on my Mac Pro (clips on the internal software raid 0) and on our new iMac Core i3 3.0GHz office Mac. This was to get a guide as to how much improvement I might see. The same avchd card was used but stored on the desktop of the i3 iMac and rendered out to the desktop too. I know this is a no-no, but I do not have a free external FW800 drive. The results were surprising. The i3 killed the woodcrest xeons! I had highest quality palyback with no glitches at all on the i3!


      I also tested transcoding to AIC on both machines and the i3 took 2.93 minutes to transcode 10 clips whilst the dual dual-core xeons took 4.32 mins.


      Now the question is this:


      Does anyone own or know if the 2.8 GHz Mac Pro will playback and allow for avchd to be edited natively? I believe from another thread that the iMac 2.93 can do so. However I would not be able to monitor the video for CC - is this correct? I am also restricted to FW800 - but would this be an issue for avchd?


      I would prefer the Mac Pro but need someone to reinforce my reasonings given the cost differences between the two systems.


      I mainly output BD but also to the web and for podcasts.



        • 1. Re: i7 27" iMac or Mac Pro for avchd to BD and web?
          ECBowen Most Valuable Participant

          I am not sure what benchmarks you saw that the IMac is faster than the current Mac Pro but that is definitely not the overall case. It may have been for that 1 benchmark where only 1 thread was used but beyond that that is absolutely not the norm.


          You are comparing Apples to oranges with your test you ran yourself. The 2008 Mac has far slower ram performance compared to the current I7/I5/I3 CPU line and that makes a huge difference with HD material especially higher compression codecs. If you compare a 2010 Mac Pro to an IMac I3 then the Mac Pro will definitely out performance the IMac. That would be a proper comparison. A current Mac Pro can handle AVCHD playback with 1 track, maybe 2. Beyond that it will depend if you get the Mac Quadro 4000 or not. Either way it will be far better than the previous Mac Pro.




          1 person found this helpful
          • 2. Re: i7 27" iMac or Mac Pro for avchd to BD and web?
            gerbow Level 1

            Thanks for your response.

            My Mac Pro is the 2006 variety not the 2008 variety. The 2008 Octocores are still faster than the new Mac Pros in some benchmarks. I do not want a 2008 used machine though as any machine I purchase would have the applecare added to it for 3 years peace of mind and support.


            The becnhmarks I read were at:





            which shows the iMac 2.93 GHz i7 is faster than some Mac Pros.


            The single Xeon 2.8Ghz Mac Pro 2010 uses 1066 Ram. The iMac 2.93 GHz i7 uses 1333.


            The advantages for Mac Pro are 3 PCIe slots for video monitoring, etc, easy HDD upgrades and graphics card upgrade to e.g. the new Quadro card.


            I just need confirmation that getting the Mac Pro is the right thing to do and that the difference of 0.13 GHz is not going to make that much of a difference.


            With a tapeless workflow I only need video out for monitoring, although I could do that by scopes alone?

            • 3. Re: i7 27" iMac or Mac Pro for avchd to BD and web?
              ECBowen Most Valuable Participant

              The Imac uses So-Dimms which are laptop ram in Dual Channel mode. The Mac Pro uses Desktop Ram in Tri-Channel mode if you configure it properly. Since many buy the Mac Pro with the incorrect ram configuration, benchmarks are not consistent or reliable. The difference between Ram bandwidth in dual channel mode and Tr-Channel with Numa support is far greater than 1333 versus 1066. The Imac ram performance is around 17GB/s a sec. The Dual Mac Pro Ram bandwidth at 1066 is around 31GB/s. As you can see the ram performance on the Mac Pro is almost twice what the Imac is. The benchmarks you see where an older Mac out performs a newer one are suspect at best because it's often related to threading. If the benchmark test does not thread very well then  you won't see much performance gap and which ever CPU has the higher GHz will win. If you have a proper benchmark that threads very well then it's no comparison. If you are looking for confirmation that an IMac is cheaper and better, I can't give it to you. It's really a glorified laptop and nothing more.  The CPU's, Ram, HDD's, and video card are far faster in a Mac Pro. That means there is no conceivable way that an Imac can out perform one unless the benchmarks are skewed.




              • 4. Re: i7 27" iMac or Mac Pro for avchd to BD and web?
                gerbow Level 1

                Great. Thanks for the really useful info. I just picked up my new Mac Pro from a local apple premium reseller. Now I'll be picking up the third party ram, and an SSD. I should pick up three sticks of ram (either crucial or kingston?) and not fill all four slots because that would be the optimum for triple channel DDR3. Strange why apple chose to have 4 slots in the memory riser. This one is not like mine where the ram had to be arranged in a specific order is it?


                Can I transfer my current raid disks across as they are? Will the new machine recognise them as raided?


                Thanks once again

                • 5. Re: i7 27" iMac or Mac Pro for avchd to BD and web?
                  ECBowen Most Valuable Participant

                  I am not sure why they did that as well since the tri channel mode only works with 3 sticks. There is another company who also has a systemboard with 4 ram slots and rumor has it the same Manufacturer makes the boards for both Apple and the other company. I can't confirm that but it would explain allot. However it is likely Apple did not want to have limited max ram options when compared to current Xeon boards and systems. Why buy a Mac Pro that maxes at 24GB of ram when I can get a Xeon PC system with 48 or 96GB. So since they could not have 6 slots for each cpu they likely chose 4 since that fits with their tower and board setup. This gives them a 32GB max although I believe some are using or have installed 8GB sticks and gotten them to work. I have not confirmed that either.


                  Yes the ram has to go into the first 3 slots.


                  Yes you can transfer your raid and OSX should reconize the raid volume. However you always run a backup before you migrate a raid. That is a must.