Document how to select the different WaveNet voices on cloud text-to-speech

[alexanderkjeldaas]

The cli documentation doesn't explain how to choose the specific cloud text-to-speech voices. Adding an example would be useful.

[eheikes]

Hi @alexanderkjeldaas. Did you see the --voice option in the docs? What information is missing that you would like to see?

[alexanderkjeldaas]

I think maybe an example of a text-to-spech voice name in the documentation would solve the issue. The problem is that there are no examples for GCP, only for Polly.

I also think a comment regarding how to specify wavelet vs normal voices would be useful. As it stands, it says the voice is selected using --language and --gender, but that begs the question whether it will be standard or wavelet, and how to choose.

[eheikes]

GCP provides 2 methods for selecting a voice -- automatically choosing one from the language and gender you specify, or using the one you explicitly specify with voice.

As I understand it, Google doesn't let you specify WaveNet vs normal with the language + gender option. If you want one type specifically, you should use --voice instead to explicitly choose one from their list of voices, e.g.:

$ tts test.ssml test.mp3 --service gcp --voice en-US-Wavenet-B