使用softvol时，Alsa amixer会列出播放和捕获设备

I'm using alsa with dmix and softvol to mix multiple sound sources and control their individual volumes. This works but there is a thing that's bothering me. The mixer control show When i play back a wave file with aplay. But the description mentions a playback and a capture channel but i want to use separate controls for both playback and capture. This is my amixer output:I'm using alsa with dmix and softvol to mix mul