ALSA PCM State Machine

Note to self   1. PCM state (snd_pcm_state_t) [1] SND_PCM_STATE_OPEN SND_PCM_STATE_SETUP SND_PCM_STATE_PREPARED SND_PCM_STATE_RUNNING SND_PCM_STATE_XRUN SND_PCM_STATE_DRAINING SND_PCM_STATE_PAUSED SND_PCM_STATE_SUSPENDED SND_PCM_STATE_DISCONNECTED   State Machine [2]     References [1] snd_pcm_state_t [2] ALSA project – the C library reference