Time-stretching is the act of changing the speed, or tempo, of a song without affecting its pitch or key. Time-stretching is an extremely powerful tool for digital DJs, but it can result in unpleasant sonic artifacts. Fortunately, Torq® software provides an easy way to minimize these negative effects and deliver clean, transparent sound.

Torq lets you choose between the Standard and Elastique time-stretching algorithms.

Torq's Standard time-stretching algorithm (available in all versions of Torq) works by breaking up the audio into extremely tiny "slices" that can be stretched apart from one another in order to slow the playback tempo, or overlapped to speed it up. Torq slices the audio in rhythm with the music, so that any transients, or sharp sounds, occur at the beginning of each slice. As a result, Torq can simply repeat the last half of the slice, which avoids repeating the transient. (Learn more about the basic principles of time-stretching.)

But how does Torq know the rhythmic timing for these slices? The answer is simple: the Beat Grid. When a song is loaded into Torq, the software analyzes it for its tempo (BPM) and also attempts to determine the first beat of the song, called the downbeat. Once this has been done, Torq superimposes a set of gray lines over the main waveform at the center of the Torq display—this set of gray lines is the Beat Grid. The Beat Grid's main function is to allow Torq to synchronize the songs, effects, and MIDI devices. However, the Standard time-stretching algorithm also uses the position of the Beat Grid to determine the location of the audio slices.

Notice how the top track's downbeats don't align with the beat grid

Therefore, even if you never expect to use Torq's auto-sync feature for beat-matching tracks, it is still very important to set the Beat Grid to the proper tempo and downbeat. Most of the time, the tempo will already be correct, but you may need to adjust the location of the downbeat. You can quickly change the downbeat by holding the SHIFT key on your keyboard, then using your mouse to click-and-drag the Beat Grid to a new location in the waveform. While it's most important to line up the Grid Lines with the beats of the song, we also recommend that you line up the thicker Grid Line with the downbeat of the song. If you do this once, you'll never have to do it again—Torq saves the position of the Beat Grid with each song.

Now the top track is aligned with the beat grid

Once the Beat Grid is properly aligned, the Standard time-stretching algorithm will sound much better and will be less prone to repeating any transients. You'll then be able to stretch the song further from its original tempo with fewer artifacts.

If you choose to use the élastique algorithm (available in Torq 1.5 and higher), you don't need to set the Beat Grid since that algorithm uses a much more complex mechanism for stretching audio than the Standard algorithm. Nevertheless, it is still recommended that you align the Beat Grid—it only takes a moment!—to ensure all of Torq's tempo-synced effects and external MIDI devices will sync up properly.