> You will get different results depending on the OS.
Would be no different than making web pages. Even JS isn't same across browsers. The big question is do I want to use a JS-TTS library or native and I think native will always be better performance/resource wise.
> And each will have its own list of available voices and languages, etc.
That can easily be solved by window.speech.listvoices like I mentioned in my post above.
> exactly how things will sound, you can include exactly the voices and languages you want, and only have to test once.
I've been programming for 20 years and that hasn't happened for any system, ever, not even once. You always have to test on different devices, OSs, platforms, browsers etc.
I agree that making web pages takes a lot of testing on different browsers and OSes. And that, as you said, there is no write-once-run-anywhere in software. But I think we should minimize the problem, not make it worse. Having the same JS TTS gets you much closer to the ideal, using system TTS gets you farther.
I do agree that a native library will have better performance, I am estimating something like 3-5X faster in the near future. So that is a benefit to the system TTS approach. But even the fairly unoptimized version in this online demo isn't too slow to be useful, I don't think, and it can be made much faster if necessary. I haven't focused on speed yet.
My concern with each OS having its own voices is that the names of the voices aren't enough to know what your users will hear. Unless we have a standard for TTS that includes the actual voice data, otherwise say "male UK English" may sound very different on different platforms.
It's clear there are tradeoffs here, both ways, and you make sound points. But I prefer the JS TTS approach, unless you are writing something like an iPad-specific app. If you don't care about other platforms, then I agree, system TTS is better.
Would be no different than making web pages. Even JS isn't same across browsers. The big question is do I want to use a JS-TTS library or native and I think native will always be better performance/resource wise.
> And each will have its own list of available voices and languages, etc.
That can easily be solved by window.speech.listvoices like I mentioned in my post above.
> exactly how things will sound, you can include exactly the voices and languages you want, and only have to test once.
I've been programming for 20 years and that hasn't happened for any system, ever, not even once. You always have to test on different devices, OSs, platforms, browsers etc.