You can detect the tempo of one or more selected audio regions and use the detected tempo in several ways. The regions can be of any length and need not align to a beat or other grid value. Uses for detecting the tempo include conforming the project tempo to an audio file without a constant tempo (such as a live recording), conforming the tempo of an imported audio file of unknown tempo to the project tempo using Flex Time, and creating a “mashup” of two or more audio recordings.
Using the controls in the Detect Tempo dialog, you can apply the detected tempo to the project (for the duration of the regions, or until the project end), use the average tempo, enable Flex Time for the selected regions, and nudge the selected regions to the nearest beat.
By default, the detected tempo is written to the audio files for the regions. Follow this default behavior except in unusual cases, such as when an audio file shared between projects has different tempi in each project. You can also write the average tempo to the audio files, rather than the precise detected tempo. In general, do this only when they are relatively short loops with a nearly constant tempo.
In the Tracks area, select one or more audio regions.
Choose Edit > Tempo > Detect Tempo of Selected Region.
The Detect Tempo window opens, showing the detected tempo and other related values (2x, 1/2x, and so on.).
In the Detect Tempo window, do any of the following:
To apply the detected tempo to the project: Starting from the beginning of the first selected region, select the Apply Region Tempo to Project checkbox.
In general, use this only when there are no other audio regions in the same section of the timeline except for Apple Loops, or regions on tracks in Flex mode.
To use the average tempo of the selected regions: Select the Use Average Tempo checkbox below Apply Region Tempo to Project.
Note: Using an average tempo might lead to deviations between the project tempo and the tempo of the regions if the audio material does not have a constant tempo, unless you also enable Flex Time.
To have the detected tempo continue after the end of the last selected region: Select the Continue With New Tempo After Region End checkbox.
In general, use this when the area after the last selected region contains only MIDI regions or Apple Loops or both, or is empty.
To enable Flex Time for the selected regions: Select the Enable Flex Time checkbox.
In most cases you should either apply the region tempo to the project or enable Flex Time.
In the Advanced Options area of the Detect Tempo window, do any of the following:
To disable writing the tempo to the audio files: Deselect the Write Tempo Information to Audio File checkbox.
In most cases this checkbox should remain selected, particularly when Flex Time is enabled.
To write the average tempo to the audio files: Select the Use Average Tempo checkbox.
Note: Using an average tempo might lead to deviations between the project tempo and the tempo of the regions if the audio material does not have a constant tempo, unless you also enable Flex Time.
To keep the selected regions in their current time position: Deselect the Nudge Regions to Beat checkbox.
In most cases this checkbox should remain selected.
Click OK.