最近在学习linux的ALSA 框架， 对于其中snd_pcm_runtime结构体中的几个成员变量很是困惑，不懂它的用处是什么？？？
/* -- SW params -- */
int tstamp_mode; /* mmap timestamp is updated */
unsigned int period_step;
snd_pcm_uframes_t start_threshold;
snd_pcm_uframes_t stop_threshold;
snd_pcm_uframes_t silence_threshold; /* Silence filling happens when
noise is nearest than this */
snd_pcm_uframes_t silence_size; /* Silence filling size */
snd_pcm_uframes_t boundary; /* pointers wrap point */
snd_pcm_uframes_t silence_start; /* starting pointer to silence area */
snd_pcm_uframes_t silence_filled; /* size filled with silence */
snd_pcm_uframes_t buffer_size; /* buffer size */
snd_pcm_uframes_t min_align; /* Min alignment for the format */
snd_pcm_uframes_t hw_ptr_base; /* Position at buffer restart */
snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time */
谁能详细帮我解释下，他们的用处，虽然有英文解释，但还不是不太明白。。
snd_pcm_playback_silence（）这个函数一直没看懂，困惑！！
拜求高人指点呀！！ ４４５９４７１６２＠ｑｑ．ｃｏｍ
