I’m using flitecontroller to generate wav files; I’ve modified the openears framework accordingly, saving the file instead of sending it to the AVSoundPlayer to speak. I play the wavs with an existing (cocos2d-based) sound engine.

However I would like to increase the volume of the flite output. Relative to music at the same volume setting, its very hard to hear.

I found the flit->gain in rate_conv.c, set to 0.8. I’ve tried setting this as high as 20 but I think it only goes up to 1.0. In any event, its still too low for me.

The app I’m using this in previously used speech files generated on a server using Festival, and to make those loud enough I had passed a -scale parameter of 2 to the text2wave program. I don’t really see any corresponding volume scaling feature in flite.

Any thoughts?

I think in this case I’d just write a little gain-increasing method to loop through buffers of the returned TTS speech right before they are added to the virtual WAV file in FliteController and boost them. I like this StackOverflow thread for a good starting point:

http://stackoverflow.com/questions/3982723/audio-processing-playing-with-volume-level

That SO question has the goods. I’m not much for C programming, but I know how to use a C function in an Obj C class, so I used the ScaleAudioFileAmplitude function shown there.

This probably is a bit wasteful, as my modified flitecontroller writes the data to file then reads/writes it again with the amplification, but it works very well. And quicker than me figuring out how to iterate through the data part of the buffer in memory.