Set a callback that runs when a channel has finished playing.
void Mix_ChannelFinished(void (SDLCALL *channel_finished)(int channel));
the callback function to become the new notification mechanism.
The callback may be called from the mixer's audio callback or it could be called as a result of Mix_HaltChannel(), etc.
The callback has a single parameter,
channel, which says what mixer channel has just stopped.
Do not call SDL_LockAudio() from this callback; you will either be inside the audio callback, or SDL_mixer will explicitly lock the audio before calling your callback.
A NULL pointer will disable the callback.
This function is available since SDL_mixer 2.0.0.