In this tutorial, I'll teach you how to change the tempo of a song in Pro Tools. You can use this method to change the tempo without affecting the pitch of a song.
Basic Setup
The first step in changing the tempo of a song is to determine the original tempo. First, import the song into Pro Tools by using the Control-Shift-I shortcut or by choosing File > Import > Audio.
Once you’ve imported the song into your project, play the song and figure out the tempo of the song by using any of the previous methods that I’ve taught. In case you missed it, read the earlier tutorial How to Find the Tempo in Pro Tools.
Once you’ve established the tempo of the song, it's easy to change it to another value.
First, turn on the Conductor Track. This will make changing the tempo of the song even simpler. If you enable the Conductor Track, you will be able to adjust the tempo of the track in different positions. You can use this method to remix songs and adjust the speed and tempo of the songs.
If you’ve read the previous article on finding the tempo, you may have already arranged the track on the correct bar and beat. Doing this will help a lot in cutting and moving the pieces of the song around.
Although arranging the track to the bar and beat is not very important, it is definitely a good practice.
Ticks and Samples
After all the basic configurations are done, the next stage is to change the track to ticks.
Pro Tools sets audio tracks to samples and MIDI tracks to ticks by default. If an audio track is in samples, changing the tempo to affect the speed of the song will not work. When a track is in ticks, the audio will be processed in relative time, according to the tempo set in the location.
To change a track into Ticks, click on the bottom left side of the track. It is called the Timebase Selector. There'll be a blue dot if the track is in Samples.
Click on the blue dot and select Ticks from the drop-down menu. Click on the Elastic Audio Plugin Selector (the small grey triangle to the right of the Timebase selector) and select any of the following plugins:
Polyphonic
This one is a good option when dealing with songs and tracks that have a lot of different instruments in them. Click on the plugin to open the plugin settings.
Here, you can adjust the Window value to get to the correct processing that you want. The Follow button enables the envelope follower, which makes the sound stretching sound smoother by following the acoustic quality of the track being stretched.
If the track has
a lot of rhythm sections, set the window to 20ms or less. If it’s more like a pad or smooth long
sections, you can set the window to around 60ms or more. These numbers are just
guidelines—you should listen to the track after you process to see if it sounds
good or not.
Rhythmic
This is suitable for tracks that have a lot more rhythm content than vocals. Tracks that have a lot of sharp attacks can be processed with this plugin. Drum loops and samples can be easily processed while using this plugin.
Click on the Rhythmic plugin to view the configurable options. Higher decay values fill the stretched track with audio that makes the sound feel a lot smoother. Lower decay values remove the audio that is between the high attack points, and the track will sound a lot cleaner, but without any decay.
Monophonic
This plugin is the best for processing vocal tracks. This plugin has no configurable options and takes longer to process than the other plugins. You can also use this for lead tracks or single-note tracks such as bass or flute.
Varispeed
This plugin is particularly useful for creating interesting effects. Try this on any audio track. Increase the tempo slowly and you will find that the audio sounds as if it is being fast-forwarded like a tape machine.
This plugin can be used to bring in funny effects as well.
X-Form
This is the best option for stretching different types of audio. This plugin cannot be used in real time—it can be used only after rendering. Although it takes a lot of time to process the audio, it provides the best quality output.
Click on the plugin to change the speed and the quality of the process. Enable the Formant option to get a better, cleaner output.
The last two options are available according to the plugins that are selected. Enable Realtime Processing to make the plugin do the processing in real time. Rendered Processing will first apply the effect to the audio and then render it. The audio will be offline while the audio is processed. You will be able to hear the audio only after the rendering is over.
To see the progress of the processing being done to the audio, open the Task Manager by selecting Windows > Task Manager. You can also use the shortcut Alt-‘.
Final Step
The final step is to change the tempo of the session by using the Transport window.
Use the shortcut Control-1 to bring up the Transport window. Here, type in the new tempo that you want to use, and the tracks which were processed using the Elastic audio plugins will automatically stretch and adjust to the new tempo that you’ve set.
Conclusion
Using the Elastic audio plugins, you can easily change the tempo of any audio track to the tempo that you want.
Next time you're working on a remix or creating an awesome production, make use of these plugins to tempo-match and stretch the audio track, creating interesting effects using the Varispeed plugin.
Leave a comment below about your favourite methods to time stretch audio tracks.
