TextGrid: To DurationTier...

Returns a DurationTier that could scale the durations of the specified intervals of the selected TextGrid with a specified factor.

Settings

Tier number
specifies the tier with the intervals.
Time scale factor
specifies the scale factor by which the duration of a selected interval has to be multiplied.
Left transition duration
specifies how long it takes to go from a time scale factor of 1.0 to the specified one. Default a very small duration is used.
Right transition duration
specifies the time it takes to go from the specified time scale factor to 1.0. Default a very small duration is used.
Scale intervals whose labels
specifies the interval selection criterion.
...the text
specifies the text used in the selection criterion.

Algorithm

For each selected interval its duration will be specified by four points in the duration tier as the figure above shows. Given that the start time and the end time of the interval are at t1 and t4, respectively, the times of these four points will be t1, t2=t1+leftTransitionDuration, t3=t4-rightTransitionDuration and t4. The associated duration scale factors will be 1.0, timeScalefactor, timeScalefactor and 1.0, respectively.

Normally we would use very small values for the right and the left transition durations and the curve in the figure above would look more like a rectangular block instead of the trapezium above. If, on the contrary, larger values for the durations are taken, such that the sum of the left and the right transition durations exceeds the interval's width, then the ordering of the time points at t1 to t4 changes which will have unexpected results on the duration tier.

Examples

Suppose you want to change the durations of some parts in a sound. The way to go is:

1. Create a TextGrid with at least one interval tier with the segments of interest labeled.
2. Select the TextGrid and choose the To DurationTier... option.
3. Use the selected sound to create a Manipulation object from it. Check and eventually correct the pitch measurements in this object (View & Edit) as the quality of the resynthesis depends critically on the quality of the pitch measurements.
4. Select the Manipulation object and the newly created DurationTier object together and choose Replace duration tier.
5. Select the Manipulation object and choose Get resynthesis (overlap-add). The newly created sound object will have the durations of its selected intervals changed.
6. Optionally you might also want to scale the TextGrid to line up with the newly created sound too. You can do so by selecting the TextGrid and the DurationTier together and choose To TextGrid (scale times). You will get a new TextGrid that is nicely aligned with the new sound.

© djmw, June 17, 2017