This plugin adds live velocities to all notes in a selection based on the expression marking dynamics present. You can choose the exact value for each dynamic for greater control.
Additionally, this plugin will create midi volume messages for hairpins with the option to process both types and to specify the type of volume curve (you can also delete the hairpins after processing).
Linear is a smooth shape, and the two types of exponential curves represent a curve that builds quickly and then levels as well as one that starts very gradual and then becomes exponential (exponential to plateau and plateau to exponential respectively).
The latest version includes a tool for randomizing Live Start Positions. You can choose the maximum allowable shift and you can choose if it can be shifted backward, forward, or both. Wonderful way to create a more realistic performance.
There is also a built-in batch processing mode to allow you to apply your setting to as many scores as you like in one run.