Codec Freedom -- Specifications

Below are the specifications for Codec Freedom. This is work in progress. We hope for a healthy interaction with the projects defined on this page, as well as others.

The protocol names used below are:

An overview picture of codec freedom for landlines; the cellular variation is a bit simpler. Don't be alarmed by the number of blocks, they are simply a sign of a clear structure. In reality the blocks perform pretty simple functions:

Codec Freedom for G.711


Connection Profiles

These are the connection profiles that are currently considered useful. Their design is made with the intention of supporting future expansion.

Bit-insertion modes

These modes are used with codecs that deliver a continuous flow of samples; these are best delivered promptly, and any data traveling alongside should be inserted on the fly, a sample at a time.

The data inserted is sent as RS-232 bit sequences, with 8 bit data, no parity and at least 1 stop bit. This results in an 8-bit clean data interface. A break (10 or more zeroes in a sequence) leads to a RESET being delivered to higher layers.

Packet modes

These modes are used with codecs that deliver bursts that hold a sequence of samples, probably compressed as a whole; packet modes support a continuous flow of data that can be interrupted at any time to deliver such data as fast as possible, without expansion with extra bits for data.

The data offered here is sent with escapes for characters that would otherwise get distorted. This results in an 8-bit clean data interface. The remote side may send a special escape code to have a RESET delivered to higher layers.

AMQP Transport, Encryption and Authentication