http://www.volkerschatz.com/noise/alsa.htmlhtml
http://www.sabi.co.uk/Notes/linuxSoundALSA.htmllinux
http://mailman.alsa-project.org/pipermail/alsa-devel/2012-June/052588.htmlapp
Dynamic PCM
https://www.kernel.org/doc/Documentation/sound/alsa/soc/DPCM.txt
https://ez.analog.com/message/49113less
http://www.spinics.net/lists/alsa-devel/msg40127.html.net