public static extern int av_audio_fifo_space(AVAudioFifo* af);
 public static extern void av_audio_fifo_reset(AVAudioFifo* af);
 public static extern int av_audio_fifo_drain(AVAudioFifo* af, int nb_samples);
 public static extern int av_audio_fifo_read(AVAudioFifo* af, void** data, int nb_samples);
 public static extern int av_audio_fifo_realloc(AVAudioFifo* af, int nb_samples);
 public static extern void av_audio_fifo_free(AVAudioFifo* af);