Previous 1 2 Next 23 Replies Latest reply: Apr 27, 2011 7:31 AM by mactreouser
mactreouser Level 1 Level 1

Hi Guys,


Do I need to allocate (setting) as much as memory (Ram) for FCP to have a smoother playback during editing? Or...this is all about CPU power?

MacBook Pro, Mac OS X (10.6.7)
Reply by Andy Mees on Apr 27, 2011 3:05 AM Helpful

So you are trying to play back 4 streams of 1920x1080 ProRes 422 (HQ) in realtime from a single 7200rpm FW800 drive? Seems to me your issue is not with RAM, its with your storage, its not even close to what you need for what you are editing. Why are you using ProRes 422 (HQ)? That'll set you back about 220 Mbps per stream, 880 Mbps for all 4 streams, and your FW800 drive is only theoretically able to offer 800 Mbps (in reality it'll be less). What kind of content is this? If its a multicam edit then I'm guessing its not green-screen work. What is the original source footage format. If its H264 then you sure as **** don't need to be transcoding to ProRes (HQ), thats a mugs game. Chances are you would be just as pleased with the visual quality of ProRes 422 (LT), unable to spot the difference ... and it would be far more suitable for your editing setup's capabilities.


Hope it helps


All replies

  • Nick Holmes Level 7 Level 7

    There is no manual RAM allocation setting on an application basis in Mac OS X. The operating system handles it automatically.


    The 32 bit Carbon architecture of FCP means it can only address 2.5 GB plus 1.5 GB for additional frameworks.

  • mactreouser Level 1 Level 1

    I see. So, how much Ram do FCP needs? S'ld we upgrade as much as the machine c'ld handle? And, as long as the highest Ram we installed and the auto-allocating system will giving us the best performance?

  • Nick Holmes Level 7 Level 7

    4 GB max for Final Cut Pro. The rest will be allocated to the OS and other active software. Some RAM capacity may well be idle. If FCP doesn't need 4GB at a particular point, it will be allocated elsewhere.

  • Michael Bradshaw Level 5 Level 5

    I'll take a stab at this.


    You can actually measure how much RAM you need with two tools. Activity Monitor will show you the division between free, inactive, active and wired. The other tool is vm_stat.


    You only need a tiny amount of free RAM so that when any program needs to request some RAM to store information the system can hand it some free RAM. Most running programs have already requested all the RAM they need - so you don't really need much of it and the system will try to keep only a tiny slice of RAM "free". Active and Wired is RAM that is really in use by the system and the programs running.


    You can simply quit all the programs you don't need and only run FCP so that it gets the lion's share of RAM. A balanced system has less than half the RAM active and wired and the other half is "inactive" which basically is a guess as to what files and other information was once in RAM and is stored there for speed later.


    When the system runs out of RAM or needs to get something from the hard disk - a "swap" happens. These will interrupt the real time FCP and cause spinning balls and the "slowness" that drives us crazy.  You may not need more RAM but instead to isolate your working data from the boot drive where swapping events will "pause" the work FCP can do.


    Take some measurements and see what percentage of RAM is in use while you are editing. You can see over time if adding RAM or another hard drive will reduce the pauses you see. You want enough RAM to never have to have lots of swaps happening in a 15 second period. vm_stat 15 or vm_stat 60 command in terminal will show you the swaps that happen while the program is running. Add RAM when the workload is causing a lot of swaps to allow it to fit more data in RAM.


    Cheers and good luck!

  • mactreouser Level 1 Level 1

    Thanks to all & appreciate!

    I'm quite tired to the lagging "picture was lag & sound just play as normal" & sometimes might facing spinball issue too. Btw, I was using FCP alone while editing. And I was editing via FW800 on my external harddrive.


    What s'ld I do to avoid the lagging & spinball issue? It was just a 4 minutes video editing.

  • Ken Summerall, Jr. Level 3 Level 3

    It would help if we knew what your video format and sequence settings are. Also, how many video tracks are you layering? You said a FW800 drive, does it have plenty of free space? Is it a 7200RPM drive?


    In other words, there are a lot of things that can cause the issue you are describing. Give us some more info and perhaps we can help.



  • Michael Bradshaw Level 5 Level 5

    mactreouser wrote:


    What s'ld I do to avoid the lagging & spinball issue? It was just a 4 minutes video editing.


    Three terminal windows may help narrow down the cause of the lag and slowness:

    • vm_stat 5 - this will let you see if swapping is indeed the major cause of the delays
    • sudo fs_usage -w| grep -v 0.0 - will show all the really slow IO operations so you can see which drives, which files and which programs
    • sudo fs_usage -w | grep "Final Cut" - will show just the IO for one program - you may want to add | grep -v 0.00 to filter out the really fast IO - they won't be causing big hold ups.


    Also - it's a good idea to start these programs and watch for other processes that are slow and get a feel for what information is happening before you even start Final Cut - you're looking for things that are new or unique when running that one program and don't want to mistake things that happen all the time. It's easy to get lost in the sea of data...


    I haven't seen a great tutorial on Mac vm_stat - but you can consult IBM documentation on tuning for great background. You will have to translate the column headers - but the ideas of virtual memory are mostly the same between AIX / Linux / darwin / mac / and other Unix systems. You want to keep the IO to the swap space low to not interfere with other IO that your program needs.

  • Studio X Level 7 Level 7

    Smoother playback is most often a function of hard drive throughput.


    If you don't have a big enough pipe, your playback is not going to be smooth.



  • mactreouser Level 1 Level 1

    Here you go:~


    Full HD Editing.

    4 Multi-Cam

    Ext.HDrive - 750GB 7200rpm (300GB of Project) ,which means about 400GB of Free Space


    So, CPU Power will not an issue?

  • mactreouser Level 1 Level 1

    Erm...then we s'ld look for Big Pipe of Thunderbolt? haaa...

  • SoCal Level 4 Level 4

    Full HD Editing

    This is a term made up by retailers to sell products.  In the world of video production it means absolutely nothing.


    I bet you are working with H.264 which is not an editing codec. In the Browser scroll to the right until you find the Compressor column.  What does it say your footage is in?  Is it an editing codec?  Does that match your sequence?

  • Patrick Sheffield Level 7 Level 7

    You still haven't mentioned what codec you're using. If, for instance, you're using H.264 that can cause all kinds of significant issues.


    Also the duration of the timeline has some bearing as FCP needs to cue up all the pending reads from all those files all over your hard disk. So, how long is your timeline?


    Stuff like that - very important...



  • mactreouser Level 1 Level 1

    Sorry, my bad. Apple ProRess HQ is what I use for editing.

  • mactreouser Level 1 Level 1

    All I mentioned above was during editing time (after transcode). That's what I'm quite tired to...haaa..

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