Samplitude Pro X now includes a dedicated Tempo track and this tutorial shows you how to use it. Here's the Introduction: Sometimes you may need to work on an audio recording which has not been recorded to click track. Problems can arise when this song doesn't conform to a Tempo map. For example: midi parts or tempo-based effects will not synchronise because the audio doesn't recognise the current Tempo grid. In this situation it will be necessary to create a Tempo map based on the varying Tempo of the project.
If time signature changes are included this will provide an extra challenge.
This tutorial will provide you with necessary information to facilitate Tempo and time signature mapping with Samplitude Pro X.