snd_pcm_hw_param_value —
int snd_pcm_hw_param_value
(const struct snd_pcm_hw_params * params, snd_pcm_hw_param_t var, int * dir);
the hw_params instance
parameter to retrieve
pointer to the direction (-1,0,1) or NULL
Return the value for field PAR if it's fixed in configuration space defined by PARAMS. Return -EINVAL otherwise