ANSI/SCTE 24-22 2007

This document contains the description of an algorithm for coding of speech signals sampled at 8 kHz. The algorithm,called iLBC, uses a block-independent linear-predictive coding (LPC) algorithm and has support for two basic frame lengths: 20 ms at 15.2 kbit/s and 30 ms at 13.33 kbit/s. When the codec operates at block lengths of 20 ms, it produces 304 bits per block, which SHOULD be packetized as in RFC 3952. Similarly, for block lengths of 30 ms it produces 400 bits per block, which SHOULD be packetized as in RFC 3952. The two modes for the different frame sizes operate in a very similar way. When they differ it is explicitly stated in the text, usually with the notation x/y, where x refers to the 20 ms mode and y refers to the 30 ms mode.