The new engine allows the importation of Vocaloid 2 and Vocaloid 3 vocals, though Vocaloid 2 vocals must have already been imported into Vocaloid 3 for this to work. The new engine includes other features, but not all of them are accessible by Vocaloid 2 and Vocaloid 3 vocals. One of the new features is a "Growl" feature which allows vocals built for Vocaloid 4 to take on a growl-like property in their singing results. Cross-synthesis was also added, allowing the user to switch between two of a character's vocals built for the same language smoothly using a time-varying parameter. This feature is accessible by Vocaloid 3 and Vocaloid 4 vocals, but not Vocaloid 2. Another feature included is Pitch Rendering, which all imported vocals can use. This displays the effective pitch curve on the user interface. Finally, real-time input has been included in this version and is another feature which all vocals can use. VSQX files made for Vocaloid 3 work in Vocaloid 4.