Transitions DJ

Tempo and Beats

Tempo refers to the speed at which a song is playing. It represents the time interval between beats in a song and is measured in beats per minute (BPM). Tempo is used by Transitions DJ to synchronize playback between songs.

When you add songs to the library, Transitions DJ will analyze the song and try to automatically determine the correct tempo and the beat locations in the song. The analyzer works well for songs recorded using an electronic clock to keep the rhythm, such as electronic and hiphop, but not for genres such as rock where the there are variations in the tempo.

Transitions DJ has several functions for manually changing the tempo when automatic BPM detection fails. The simplest way to correct the tempo is to use the BPM tap function. The BPM tap function will allow you to tap along with the beat of the music using the mouse and will reanalyze the song based on the taps. The BPM tap function will only work for songs will with a constant tempo.

For songs with multiple or variable tempos, the beat grid must be edited manually. The beat grid editing mode is available for adding and editing an unlimited number of different tempos, allowing complex time warping of the musical signal.

BPM Tap Function

The BPM tap function allows you to specify the tempo of a song by tapping along with the music using the mouse. To specify the BPM using the tap function:

  1. Move the mouse over the BPM text field. The BPM text field is located between the song title and time fields on the waveform display. After moving over the BPM text field, the field should display "TAP".
  2. Begin tapping the left mouse button in time with the beat. Continue tapping for at least 4 beats and don't skip any beats.
  3. Stop tapping and wait several seconds for the BPM to be recalculated. If you missed a beat during tapping, or the calculated tempo is incorrect, you can repeat the previous steps. If the BPM is still incorrect after several attempts, you may need to manually set the BPM using the beat grid editing mode, described in the following sections.

Beat Grid

The beat grid is represented by the gray lines in the waveform view. You may have to zoom in before the lines become visible. When zoomed far out, the beat lines are not drawn. As you move in, gray lines will first appear representing the bar or measure boundaries. A measure boundary marks the location of the first beat of the measure, also called the downbeat. If you zoom in enough, lines representing individual beats will become visible, with the downbeats now drawn using thicker lines.

Beat Grid Editing Mode

Holding down the ALT key will enter beat grid editing mode. You can tell you are in beat grid editing mode when the beat grid is highlighted. You may also notice the appearance of one or more triangular shaped markers along the top of the grid. These markers represent anchor beats which can be moved to alter the alignment of the beat grid.

Shifting the Beat Grid

In some cases, the Transitions DJ analyzer may misalign the beat grid. Often, the beats are aligned correctly, but the bar boundaries do not align with the downbeats. To shift the beat grid, hold down ALT to enter tempo editing mode and use the mouse to drag the strip above the waveform. This is the region containing the phrase annotation labels. The mouse cursor will change to a hand when moved over the region. You can also shift the tempo grid by pressing ALT in combination with the left and right arrow keys. Each key press shifts the beat grid one-half beat. Alternatively, shifting is available using the menu commands Shift Left and Shift Right in the Tempo menu.

Changing the BPM

Transitions DJ provides a couple of methods for changing the BPM in case the tempo analyzer detected the incorrect BPM. Much of the time, the BPM is detected incorrectly by a factor of 2, such as 70 BPM instead of 140 BPM. In this special case, you may use the keyboard shortcuts ALT-Up and ALT-Down to double or halve the BPM, respectively. These shortcuts are also available using the commands Double BPM and Halve BPM in the Tempo menu.

In cases where the BPM is not off by a factor of two, you will need to enter beat grid editing mode and manually edit the tempo. The BPM can be altered by expanding and contracting the beat grid.

  1. Hold down the ALT key to enter tempo editing mode.
  2. Click and hold down the mouse anywhere inside the waveform view away from an anchor beat.
  3. Drag the mouse to expand or contract the beats. Moving the beats farther apart decreases the BPM. Moving the the beats closer together increases the BPM.

Correcting the Beat Grid

A general strategy for matching the beat grid to the beats uses a combination of shifting the beat grid and changing the BPM.

  1. Locate the triangular shaped tempo anchor marker.
  2. Find a downbeat in the song. The downbeat is the first beat in a bar, usually a bass note.
  3. Shift the tempo grid so that the anchor marker is aligned with the downbeat.
  4. Find the next beat after the downbeat and drag the tempo grid so that the first grid line after the marker aligns with this beat.
  5. The tempo should now be close to the correct tempo, but will still need some refinement. Look at subsequent beats and make sure they line up with the tempo grid. If the tempo grid lines are drifting away from the beats, drag the grid to bring it back into alignment.
  6. Repeat step 3 until all beats in the song are aligned with the tempo grid.