Add audio effects

[achimmihca]

Actual behaviour

Currently, the mic playback returns the mic input as-is. Similarly, there are no modifications to the played song audio.

Expected behaviour

It could be fun to add audio effects. For example,

• change pitch of audio (like StarMaker app)
• change speed of audio (i.e. speed up / slow down, e.g. for custom game modes such as collecting items)
• option for audio effects on mic playback (like Smule / StarMaker app, it can make the singing of non-professionals more pleasant)