It would be really useful to be able apply a high quality tempo change which is spread linearly over the marked duration. So if you entered -20% for example, the tempo woul be unchanged at the beginning of the marked passage, and down by twenty percent when it reaches the end. Is this already possible and if not might it be a nice addition?
Time track … Time Tracks - Audacity Manual, (changes tempo & pitch).
If you want to keep pitch constant … Sliding Stretch - Audacity Manual (artifacty)
Thank you!