Pro Tools offers five different playback modes. These can be accessed by right-clicking the play button on the transport bar or from the transport controls in the toolbar at the top of the edit window if you have them displayed. If you want to customise your toolbar simply right-click on some empty space and select the element you wish to add or remove (see below). By far the most commonly used playback modes are Normal and Loop but there are others and they are definitely worth being aware of even if they are rarely used, I have had several experiences of confused people wondering what is wrong with their session when they have accidentally triggered half-speed playback!
The five playback modes are:
- Half Speed Playback
- Prime for Playback
- Dynamic Transport
As this is the default behaviour it is easy to overlook, so much so that I had to go back and change this post from four playback modes to five - I forgot about it. You’re in Normal mode when you aren’t in any of the others. Pro Tools plays back at the correct speed without looping, basically its normal…
In loop playback mode a loop symbol is displayed on the play button and a tick is displayed next to loop in the drop down playback modes menu. In this mode Pro Tools will loop the current timeline selection as long as it is over half a second long. Your edit and timeline selections are likely to be linked so it may appear that the edit selection is being looped but it is actually based on the timeline selection. Try it unlinked and you’ll see. If you are unsure about timeline and edit selections and the significance of linking them read my article on on it here. If your (linked) edit selection disappears when you hit stop you need to press N to switch off insertion follows playback. If you don’t know what that means it is all explained in the article linked to earlier.
Loop playback can be toggled using 4 on the numeric keypad, by pressing command+shift+L (control+shift+L on the PC) or by control-clicking on the play button.
Half Speed Playback
Half speed playback plays back audio and half speed with the corresponding drop in pitch of an octave that you would expect if an audio file was played back at half speed. I used to assume that half speed playback halved the sample rate of the session during playback but if you play back a software instrument at half speed the pitch is unaffected which suggests that each sample is played back twice giving the effect of half speed playback but leaving the session sample rate unaffected. Half speed playback can be useful in critical listening applications, trying to decipher fast passages of music or speech but in reality I find I use the scrub tool and shuttle lock modes in this application. In truth I think most people discover or are reminded about this feature when they trigger it by accident and wonder what has happened.
To play back at half speed right-click the play button and select half speed, shift-click the play button or press shift+spacebar.
Prime for Playback
This playback mode has largely been superseded by the introduction of the timeline cache in Pro Tools HD. When working with high track counts it isn’t unusual for there to be a small lag between hitting play and playback actually starting. Prime for playback buffers the timeline allowing instantaneous playback. To indicate that the transport is primed for playback the stop button illuminates blue and the play button flashes green. On hitting play playback starts immediately but prime for playback has to be invoked every time you want to use it, it does not persist to subsequent plays. Disc and timeline cacheing as introduced in Pro Tools 10 HD has largely replaced and improved on this feature but for non HD users it is available and, in the right circumstances, useful.
To prime for playback either right-click on the play button and select from the drop down menu or option-click on the play button. Option/alt and spacebar doesn’t prime for playback. Instead it puts Pro Tools “online” so that transport can be triggered by external timecode. To prime for playback use control+spacebar (start spacebar on the PC).
Choice of playback modes is typically restricted to Normal and Loop. In Pro Tools 8 Dynamic Transport was introduced and this mode is frequently overlooked. I must admit I paid little attention to it when it was introduced. It seemed to be an unnecessary addition designed to appeal to the music creation market that Pro Tools 8 was largely aimed at. That was unfair and I have since understood the benefit of Dynamic Transport. Dynamic transport is interesting enough to warrant an article all to itself which will be coming soon.