Asterisk ALSA

• Asterisks locks ALSA device if chan_alsa is loaded
• Music Player Daemon
• Asterisk config alsaconf

alsa 作为 channel

ALSA channels allow calls to be placed to/from ALSA devices, using ALSA audio input/output devices as telephony devices.

OSS

• Open Sound System

cat /dev/random > /dev/dsp # plays white noise through the speaker
cat /dev/dsp > a.a         # reads data from the microphone and copies it to file a.a