Time stretch with Elastic Audio

1. Enable Elastic Audio

Before working with Event Markers, you need to ensure that Elastic Audio is enabled on the audio track. Elastic Audio allows Pro Tools to detect transients and make time-stretching or pitch-shifting adjustments. 
How to Enable Elastic Audio:

1. In the track header, click the Elastic Audio plug-in icon (the small clock icon).

2. Choose the appropriate Elastic Audio algorithm for the type of audio you’re working with:

• Polyphonic for complex harmonic material (e.g., full mixes).
• Rhythmic for drums and percussive material.
• Monophonic for single-note instruments or vocals.
• Varispeed for simultaneously adjusting both pitch and tempo.
• X-Form for the highest quality time-stretching (requires rendering).

3. Set the track to Tick-Based or Sample-Based depending on your needs:

• Tick-Based: Follows the session tempo and will adjust if the tempo changes.
• Sample-Based: Stays locked to the timeline, unaffected by tempo changes.

Once Elastic Audio is enabled, you can proceed to adjust Event Markers to ensure accurate detection of transient events.

2. Review and edit event markers

In Pro Tools, Event Markers represent transient events—such as drum hits, notes, or other audio peaks—that Elastic Audio detects within your clip. These markers act as key control points for time-stretching and pitch-shifting, allowing you to make precise adjustments to your audio.

Pro Tools automatically detects and places Event Markers at the transients of most audio clips. However, for material with less defined transients (like legato strings or soft synth pads), the detection may be less accurate. In such cases, you can manually add, move, or delete Event Markers to improve Elastic Audio's results. Here’s how to display and edit Event Makers:

How to Display Event Markers in Analysis View

1. Click the Track View selector in the track header of the Elastic Audio-enabled track.
2. Select Analysis from the Track View pop-up menu to display Event Markers as vertical blue lines.

Editing Event Markers

After switching to Analysis View, you can manually adjust Event Markers for more accurate results:

• Add an Event Marker:
  • Use the Pencil tool to click where you want to add a new Event Marker.
  • You can also double-click with the Grabber tool, or use Control-click (Mac) / Start-click (Windows) to add a marker.
  • Alternatively, Right-click and select Add Event Marker from the pop-up menu.

• Move an Event Marker:
  • Drag the Event Marker to a new location using the Pencil or Grabber tool.

• Delete an Event Marker:
  • Option-click (Mac) or Alt-click (Windows) the Event Marker you want to remove.
  • You can also select multiple Event Markers using the Selector tool and press Delete or Backspace on your keyboard.

3. Adjust Timing with Warp Markers

Once Elastic Audio is enabled and you’ve confirmed Event Markers look accurate, you can start using Warp Markers to time-stretch or compress specific sections of your audio. Warp Markers allow you to manually stretch or compress the timing of audio between transient points (Event Markers). They act as anchor points that let you move specific parts of a clip without affecting the entire track.

Adding Warp Markers

1. Switch to Warp View: Make sure you're in Warp View by selecting it from the track view dropdown in the track header. This view lets you see the waveform and add or edit Warp markers.
2. Double-click to create a Warp Marker: To add a Warp marker, double-click anywhere on the audio clip where you want to establish a timing anchor. Warp markers appear as thick black vertical lines with a triangle at their base.

Adjusting Warp Markers

Once Warp Markers are placed, you can start adjusting the timing:

• Set Boundary Warp Markers:
  • Place Warp Markers on either side of the audio section you want to adjust. This isolates the area and ensures that the rest of the clip remains unaffected by your edits.

• Move a Warp Marker:
  • Click and drag a Warp Marker left or right along the timeline to time-stretch or compress the audio between the boundary markers.

Deleting Warp Markers

You can also remove Warp Markers if needed:

• Remove a Single Warp Marker:
  • Option-click (Mac) or Alt-click (Windows) on the Warp Marker you want to delete.

• Remove All Warp Markers in a Selection:
  • Make an Edit selection that includes the Warp Markers you want to delete.
  • Press Delete or Backspace on your keyboard, or Right-click and select Remove Warp Marker from the pop-up menu.

4. Review and final adjustments

After you've applied time-stretching and made adjustments with Warp Markers, it’s important to review the overall sound and feel of your edits. Listen through the stretched sections to ensure the timing is accurate and the audio quality meets your expectations.

Removing Clip Warping

If you have applied any warping to a clip, you can remove the warping and revert the clip to its original duration. This is useful if you're not satisfied with the results and want to return to the pre-warped clip. Note that Warp markers are not deleted when using the Remove Warp command—only the warping itself is undone.
To remove clip warping:

1. Select the clip for which you want to remove warping.
2. Do one of the following:

• Choose Clip > Remove Warp from the menu bar.
• With any Edit tool, Right-click the clip and select Remove Warp from the pop-up menu.