Feature request: Add built-in mp3 conversion

[barseghyanartur]

ffmpeg-python would be a dependency:

pip install ffmpeg-python

Sample code:

import ffmpeg

ffmpeg.input(filename).output(filename + '.mp3').run()

[Poeschl]

This will also require ffmpeg to be installed on the system. Something I find a little much for a TTS package.
I use this package in an environment where this can not guaranteed. So I suggest to convert it after the retrieval to keep this package as modular as possible

[barseghyanartur]

That would make the package more usable. If you don't consider this a core functionality, you could make it optional. It's not like I can't do that myself. It's about ease of use.

I would much prefer to replace most of that code with something like:

# Return MP3 file as bytes
return mary_tts.synth_raw_mp3(self.content)

or at least to something like this:

# Write MP3 file
with open(filename, "wb") as file:
    file.write(mary_tts.synth_mp3(self.content))

Adding a couple of additional helper methods would certainly not hurt the package. And as I said, making things optional but available makes more developers happy.