Microsoft Speech API (SAPI)
Version 5 of the Microsoft Speech API, also known as SAPI 5, is a built-in interface in Microsoft Windows to allow desktop software to install voices for text-to-speech playback and make them available to other programs like AwesomeTTS.
While Microsoft Windows comes built-in with the ability to use the Microsoft Speech API, it usually only ships with one or a small handful of voices. You can make additional voices available over the SAPI system by installing software that supports text-to-speech playback, such as Ekho, eSpeak, RHVoice, and others.
When using the Microsoft Speech API, the Speed, Volume, and Quality of the playback can be adjusted. Depending on the voice you are using, different options may produce better output (e.g. some voices produce output natively at 8 kHz, 16 kHz, or 22 kHz, and matching the quality level may avoid distortion).
Additionally, you may need to set XML handling options. If you are using an engine that has a special XML-based markup language (e.g. VTML), this can be set to pass through so that the XML will not be discarded by the SAPI subsystem itself.
If you are using another service (e.g. Ekho, eSpeak) indirectly through this interface, the options here may not produce exactly the same results as when calling those services directly, but they will be similar.