[LAD] About some interface of aplay

[SxDx]

> From: "新月如钩" <46620410 at qq.com>
>      I analyze the source code of aplay and very confused on follow
>      interfaces:
>             snd_pcm_playback_info()
>             snd_pcm_playback_format()
>             snd_pcm_playback_params()
> 
>      The aplay is belongs to alsa-utils that also is a application.
>      It should be use interfaces of alsa-lib, but why i can't find
>      these interfaces in alsa-lib ?
>      Could you tell me where can find out these interface?

what version of alsa-utils do you have?
These functions are not in alsa-utils-1.0.24.2
that I have here nor in the git repository.