Get the loop time length of music stream, in seconds.
double Mix_GetMusicLoopLengthTime(Mix_Music *music);
|music||the music object to query.|
Returns -1.0 if this feature is not used for this music or not supported for some codec
To convert to milliseconds, multiply by 1000.0.
If NULL is passed, returns duration of current playing music.
This function is available since SDL_mixer 2.6.0.