Loop Properties dialog - Audio Stretching

You have two different (and independent) ways to stretch clips: by using either Groove clips or AudioSnap. Groove Clip markers are typically placed at a zero-crossing point before a transient; AudioSnap markers are placed directly on a transient. The AudioSnap feature can extract tempo from a clip. Groove Clip stretching is preferred for more extreme stretching. There are numerous other differences between the two features (see Working with Groove Clip audio, and AudioSnap (Platinum and Professional only)).

The Audio Stretching tab has a section of options for Groove Clips, and a separate section for AudioSnap, described as follows:

Groove Clips

Both MIDI and audio clips can be set to act as groove clips. The options you see in this dialog box for audio clips are different from the options for MIDI clips.

The Groove Clips section of the Audio Stretching tab has the following options:

Enable Looping. Checking the Enable Looping check box allows you to loop clips in the Track view by dragging the right side of a clip with your mouse. When Enable Looping is not checked, you are able to slip edit the clip. For more information about slip editing, see Applying fades and crossfades offline.

Stretch to Project Tempo [audio clips only]. The Stretch to Project Tempo check box instructs SONAR to stretch or shrink the clip to fit the project’s tempo. SONAR uses the Beats in Clip and Original Tempo parameters are used to make the change.

Beats in Clip. The number of beats (quarter notes) in the clip.

Original Tempo [audio clips only]. The tempo at which the clip was recorded.

Follow Project Pitch. The Follow Project Pitch option transposes the loop, if necessary, to the key of the project. A loop recorded in the key of A, used in a project in the key of C, would be transposed up three semitones if the Follow Project Pitch check box was checked.

Reference Note. The Reference Note represents the key in which the loop was recorded. The Follow Project Pitch feature uses this information, when checked, to transpose the loop to match the project’s key.

Pitch (semitones). You can set the transposition of a clip, independent from the project pitch, using the Pitch (semitones) field. A positive number transposes the clip up by that number of semitones. A negative number transposes the clip down by that number of semitones. Remember that, if the Follow Project Pitch option is checked, the clip follows the project’s pitch, so any transposition changes you make using this option are changes to the project pitch, not the clip pitch.

An example: The project key is C. The clip key is D. If the Follow Project Pitch option is checked, the clip is transposed down by two semitones. A value entered into the Pitch (semitone) field adjusts the pitch from C. If you enter -1 the pitch would be transposed down by one additional semitone to B.

Another example: The clip pitch is E. The desired clip pitch is D. If the Follow Project Pitch option is not checked, and a value of -2 is entered in the Pitch (semitones) field, the clip is transposed down two semitones to D from the original pitch of E.

Fine Pitch (cents) [audio clips only]. The Fine Pitch (cents) field allows you to make tuning adjustments or to transpose the pitch of a clip up to 50 cents. There are 100 cents in one semitone. A Fine Pitch setting of 1 adjusts the pitch up one hundredth of a semitone. The Fine Pitch option can “fine tune” a slightly out of tune clip so that it is in pitch with the remaining clips in a project.

For more information, see:

Working with loops

Working with Groove Clip audio

Creating and editing Groove Clips

AudioSnap

The AudioSnap section of the Audio Stretching tab has the following options:

Enable AudioSnap. Enabling this check box enables the clip’s AudioSnap feature, which makes the following options available:

Show Transients. Enabling this check box displays the clip’s transients.

Add Transients to Pool. Enabling this check box displays vertical grid lines at the beginning of each of the clip’s transients, extending vertically across the Clips pane.

Auto Stretch (Follow Tempo). Enabling this check box causes the clip to automatically follow any project tempo changes.

Enable Time Stretching. This check box is unavailable if the Auto Stretch (Follow Tempo) check box is enabled, but is available whether or not the clip is AudioSnap-enabled. You can use this check box and related fields to stretch the clip by either a percentage amount, or to a new Duration, or to a new Thru Time. If you set one field, and Tab out of the field, the other 2 fields update automatically.

Stretch Amount (%). Choose by what percentage you want to stretch the clip.

New Duration. Choose what duration you want to stretch the clip to.

New Thru Time. Choose by Thru Time you want to stretch the clip to.

Online Algorithm. Choose the algorithm you want to use to stretch the clip:

Algorithm	Description
Default	This means the algorithm that is listed in the Online field of the AudioSnap Options dialog box.
Groove-Clip	This choice works faster, using less processing power.
Percussion	This is the best choice for percussive sounds.

Offline Algorithm. Choose the algorithm you want to use to stretch the clip:

Algorithm	Description
Default	This means the algorithm that is listed in the Offline Rendering field of the AudioSnap Options dialog box.
Same as Online	Uses the same choice as the Online field.
iZotope Radius Mix	This is better for clips containing polyphonic, stereo data.
iZotope Radius Solo	This is better for clips containing monophonic, solo instruments.
iZotope Radius Solo (Bass)	This is better for clips containing solo bass instruments.
iZotope Radius Solo (Vocal)	This is better for clips containing solo vocals

For more information, see AudioSnap (Platinum and Professional only).