void *sound_open(const char *audiodev, double *tx_frequency, double *rx_frequency, int channels, int samplerate, double bandwidth, double sample_deviation);
void sound_close(void *inst);
int sound_write(void *inst, int16_t **samples, int num, int channels);
int sound_read(void *inst, int16_t **samples, int num, int channels);
int sound_get_inbuffer(void *inst);