How to use tts_engine?

[ckilb]

I'm stuck using the tts engine.

• First I call tts_engine_init()
• Then I check via ttsengine_is_initialized() if it's initialized -> yes, it is
• Just to be sure I set the volume to 100 via ttsengine_setvolume()
• Now, when I call tts.ttsengine_synthtext(0, "hello foobar") I expect the text to be read.

=> It works, if I immediately before open a book in Pocketbook, view any word in dictionary and click the sound icon. Once the word has been read by Pocketbook's original software I can switch to my app and trigger the code above. I can hear "hello foobar" coming out of the device speakers.
It doesn't work though if I don't let the Pocketbook original software read some word first.
I assume the original software is initializing something more to make it work. But I can't find out what it is.

Also I wonder what's the first integer argument of tts.ttsengine_synthtext is supposed to be. It seems like it doesn't matter what I pass here. For now I tried 0 and return vaue from tts_engine_init (which just seems to be 1 all the time).