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This feature is accessible when using Vocaloid 3 and Vocaloid 4 vocals, but not Vocaloid 2.
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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. 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. The new engine includes other features, but not all of them are accessible by Vocaloid 2 and Vocaloid 3 vocals. The Vocaloid 4 engine allows the importing of Vocaloid 2 and Vocaloid 3 vocals, though Vocaloid 2 vocals must have already been imported into Vocaloid 3 for this to work. The update of the AH-Software Vocaloid 2 vocals is related to Windows 10 being released in 2015, and the impact it may have on the Vocaloid 2 software. All AH-Software vocals were also announced as receiving updated packages as well as VY1v4.
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A Vocaloid 4 version for OS X has also been released. Its release was delayed so it could be released on the newer engine. In October 2014, the first Vocaloid confirmed for the Vocaloid 4 engine was the English vocal Ruby.
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