It is possible to stretch an Audio Event to fit a tempo other than its original tempo, without changing the pitch. This is called Timestretching, and it can be used to effectively slow down or speed up an Audio Event. For instance, a one-bar drum loop recorded at 120 bpm (beats per minute) can be stretched to fit into one bar at 100 or 140 bpm without significantly changing the pitch and overall sound of the original audio.
Timestretching and defining a file tempo are nondestructive, so they can be undone and redone. It is also possible to switch Tempo modes for any Audio Track, on the fly. For example, switching to Follow or Don’t Follow from Timestretch returns any timestretched Audio Event that Track contains back to its original state.
When timestretching, if the tempo is drastically changed (by about 30 bpm or more), the audio can become slightly distorted. While this can lead to interesting effects, you should be aware of the limitation of this technology.
In Studio One, timestretching can occur automatically or manually. The following describes these functions.
With manual timestretching, you can stretch an Audio Event independently of the Song tempo or audio file tempo.
To manually stretch an Audio Event with the Arrow tool, float the mouse cursor to the edge of the target Audio Event and hold [Alt]/[Option] on the keyboard. The Timestretch tool appears, allowing you to click on the edge of the Event and drag left or right to timestretch the Event, making it shorter or longer In this case, the length of the Event changes, using the Speedup factor, but the pitch of the audio the Event contains remains the same. Only the Event that you selected for timestretching is affected.
Speedup factor is a timestretching function for making an audio clip shorter or longer while maintaining its pitch. Values greater than 1 decrease the length of the clip, while values less than 1 make the clip longer. This is used to stretch audio Events when you do not wish to define a tempo for the original audio clip, which would affect all Events associated with that clip. The Speedup factor can be entered in the Event Inspector.
Automatic timestretching is based on the relationship between the Song tempo and the audio file’s tempo.
Each Audio Track has a Tempo mode that controls the behavior of the Events on the Track, based on the Song tempo. The Tempo mode can be selected in the Track Inspector. The following modes are available:
- Don’t Follow Events on this Track are independent of the Song tempo. They are never moved or stretched automatically.
- Follow The start positions of Events on this Track are tied to the musical grid. Thus, the Events move when the Song tempo changes but they are not stretched.
- Timestretch Event start positions follow the Song tempo, as in Follow mode. In addition, the Events are stretched to fit the Song tempo.
Audio File Tempo Information
For automatic timestretching to work as described, Studio One needs to know the original tempo of an audio file. The software can then calculate how to stretch the file to fit the Song tempo. Many audio loops have this information encoded.
Files without tempo information are not timestretched, even if the Track’s tempo mode is set to Timestretch.
Studio One offers two ways to define or change the original tempo information of an audio file.
If the original tempo for an Audio Event is unknown, the Arrow tool Timestretch function can be used to manually fit the Audio Event to a specific length of time (bars and beats, etc). To do this, set the Tempo mode of the Track to “Timestretch.” Float the mouse cursor to the edge of the target Audio Event and hold [Ctrl]+[Alt]/[Cmd]+[Option] on the keyboard. The Define Tempo tool appears, allowing you to click on the edge of the Event and drag left or right to stretch it. In this case, the tempo for the original clip is set based on the musical length to which the Event is stretched, and all Events in the Song that use this original clip are updated.
If the original tempo for an Audio Event is known but is not encoded in the original file that the Event references, you can easily set the file tempo for the Event in the Inspector. Click in the File Tempo box, type in a new value and press [Enter] on the keyboard to enter a new file tempo. If the corresponding Audio Track’s Tempo mode is set to Timestretch, entering a new value in File Tempo stretches all Events in the Song that use this original clip, based on the entered tempo value.
You can use the Tap Tempo function to set the current Song tempo to the tempo that you hear in your Audio Events. To do this, repeatedly click on the word “Tempo” in the Transport, clicking once on every beat you hear. Studio One determines the Audio Event tempo based on the timing of your clicks and sets the tempo for the Song accordingly. Be sure that the Tempo mode for the Audio Track is set to Don’t Follow; otherwise, the Events are stretched or moved while you are using the Tap Tempo function, making it impossible to find a consistent tempo.
Studio One features several optimized timestretching modes that may yield better results with certain types of audio material. To access these modes, open the Inspector by pressing [F4] on the keyboard and click the Timestretch menu. Click on any mode to select it for the currently selected Track. The modes are:
- Drums Use this optimized mode on any percussion track to achieve the best results when stretching percussive audio. This mode uses the Elastique Direct algorithm.
- Sound Use this general mode on any other type of track. This mode uses the Elastique Direct Formant algorithm.
- Solo Use this optimized mode on any solo instrument or vocal track to achieve the best results. This mode uses the Elastique Pro Monophonic Formant algorithm.
Note: Some timestretch modes do not support precision timing changes. If you manipulate Bend Markers in an Event set to one of those modes, Studio One automatically slices and repositions the sections of your audio (rather than timestretching them into place) for the best results.
By default, Use Cache for Timestretched Audio Files is engaged. This option also can be selected in the Studio One/Options/Advanced/Audio Engine menu (Mac: Preferences/Advanced/Audio Engine). Timestretch Cache creates a cache file at the correct tempo for any files that need timestretching, based on what is currently being stretched in your Song. This improves Studio One’s performance, as the timestretch process no longer needs to occur during playback. Studio One also can use a higher-quality timestretch setting when it creates the cache file.
Using Timestretch Cache requires a certain amount of available space on your hard drive. If you know that space is relatively limited on your hard drive, or if performance issues arise, disable this feature. When Use Cache for Timestretched Audio Files is deselected, Studio One timestretches the file in real time during playback, as the file is being read from the computer hard drive.
Default Tempo Mode for New Tracks
When creating a New Song, notice that the New Song setup menu includes a Stretch Audio Files to Song Tempo checkbox. With this option engaged, any new Track that is created in this Song has the Tempo mode set to Timestretch, and the software attempts to automatically stretch audio files to the current Song tempo when they are imported into the Song. Otherwise, the default Tempo mode for new Tracks is Follow.