AudioSocket is a simple TCP-based protocol for sending and receiving realtime audio streams.

There exists a protocol definition (below), a Go library, and an Asterisk application.

The singular design goal of AudioSocket is to present the simplest possible audio streaming protocol, initially based on the constraints of Asterisk audio. Each packet contains a three-byte header and a variable payload. The header is composed of a one-byte type and a two-byte length indicator.

The minimum message length is three bytes: type and payload-length. Hangup indication, for instance, is 0x00 0x00 0x00.

• 0x00 - Terminate the connection (socket closure is also sufficient)
• 0x01 - Payload will contain the UUID (16-byte binary representation) for the audio stream
• 0x10 - Payload is signed linear, 16-bit, 8kHz, mono PCM (little-endian)
• 0xff - An error has occurred; payload is the (optional) application-specific error code. Asterisk-generated error codes are listed below.

The payload length is a 16-bit unsigned integer (big endian) indicating how many bytes are in the payload.

The content of the payload is defined by the header: type and length.

Error codes are application-specific. The error codes for Asterisk are single-byte, bit-packed error codes:

• 0x01 - hangup of calling party
• 0x02 - frame forwarding error
• 0x04 - memory (allocation) error