Understanding The System Usage Meters In Pro Tools

01-16-2014 12:33 PM

You may be new to Pro Tools and wonder where to go to see how Pro Tools is working with your system resources.
Under the hood at the bottom of the Window menu is a handy option called System Usage and depending on what version of Pro Tools you own it will appear a little differently.

The Basics
All Pro Tools users will have the following showing in the System Usage Window:

  • CPU - This meter displays the amount of your computer’s CPU resources that Pro Tools is using. Depending on how many cores your processor has the number shown will differ. One small thing to note is that Pro Tools displays duo chips as double the amount, so a 2.8 GHz Quad-Core Intel Xeon shows up as 8 and not 4 in this part of the window. Items that use this processing include Elastic Audio processing, Clip Gain processing, Native plug-in and mixer processing.
  • Disk - This displays the activity of the hard disk. Remember Pro Tools is a DAW and writes the audio to a hard drive, read and write access in the fastest possible time is essential so the faster your hard drive is the better, normally a 7200rpm is the starting point. Using the same drive for your Pro Tools sessions is not recommended so either use a second high speed internal hard drive or an external hard drive that is connected either by Firewire, Thunderbolt or USB2.
  • Memory - The memory meter shows how much system RAM is being used by Pro Tools. If you are using Pro Tools 10 and earlier, which are 32 bit applications, then this is limited to around 3GB, irrespective how much RAM you may have installed in your computer. Pro Tools 11 is a 64 bit application, so is theoretically able to access as much memory as you throw at it. Plug-ins, particularly Virtual Instruments with large libraries use lots of memory so it is good to have as much in your computer for Pro Tools to access. However you need to remember that Pro Tools accesses RAM for other functions too, this includes; The Audio and Video Engines, plug-ins and disk cache (if available & enabled).

The Extras
If you are using Pro Tools HD/HDX then you will have some additional information that pertains to the cards installed in your system and features only available to HD users.

From Pro Tools 10 onwards Disk Cache was made available for HD Software owners. Disk Cache allocates part of the computer’s RAM and then Pro Tools pre-loads audio that will normally stream from disk into memory. This gives faster and more snappy performance. Only those with Disk Cache will see the Disk Cache meter in the Activity window and have set a fixed Cache size in the Playback Engine window.
Pro Tools 10 has an additional meter - Timeline Cache. This displays how much of the media on your timeline is held in the cache. Pro Tools will load the media closest to the current cursor position first, until the allocated RAM is filled up, or the timeline is completely cached in which case it will display 100%. With Pro Tools 11, Avid have merged the Disk Cache and Timeline Cache meters together into one meter.

You can see in the image above a DSP meter that shows how many voices are used from those available and the number of time slots. The time slots have to do with Time Division Multiplexing (TDM) which is a digital equivalent of having a time share villa holiday. With earlier versions of Pro Tools this could be a bottleneck but with Pro Tools 11 Avid has increased the number of time slots to resolve this pressure point.
Depending on how many cards you have then you will see the HDX Card meters, you can see in this example how the load is being distributed across the card and is shared by Mixers, Dynamics, 6030 instances and Pitch II, this will differ depending on what DSP based processes and plug-ins are running.
Running Out Of Juice - Where To Look
If you find your Pro Tools system is experiencing difficulty running your sessions then the information shown in the System Usage window can help you work out what you need to do. In simple terms this is what will start to solve your issues.

  • CPU maxing out - You need to consider buying a machine with a faster processor.
  • Disk maxing out - You need to consider buying a faster drive or an external drive with a high speed data connection. If you have HD software then you can first try allocating any spare memory to the Disk Cache, this will alleviate some of the Disk issues.
  • Memory maxing out - If you are running Pro Tools 10 and below then you can increase your computer RAM memory but remember as it is a 32 bit application then anything over and above 3GB can’t be accessed by Pro Tools and so won’t help Pro Tools - it may help take pressure off for other system resources outside of Pro Tools. If you are running Pro Tools 11 then put as much memory as you can into your computer.
  • DSP maxing out - Consider buying another HDX card.
  • HDX card maxing out - Again consider buying another HDX card.

If you plan to run sessions with lots of virtual instruments then think carefully before investing in Pro Tools HD or HDX, nearly all VIs are native plug-ins so would not access the DSP cards anyway. DSP may help free up some of the plug-ins using native processing but it won’t solve all your problems.