Browse Prior Art Database

Internet Low Bit Rate Codec (iLBC) (RFC3951)

IP.com Disclosure Number: IPCOM000033253D
Original Publication Date: 2004-Dec-01
Included in the Prior Art Database: 2004-Dec-02

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S. Andersen: AUTHOR [+6]

Abstract

This document specifies a speech codec suitable for robust voice communication over IP. The codec is developed by Global IP Sound (GIPS). It is designed for narrow band speech and results in a payload bit rate of 13.33 kbit/s for 30 ms frames and 15.20 kbit/s for 20 ms frames. The codec enables graceful speech quality degradation in the case of lost frames, which occurs in connection with lost or delayed IP packets.

This text was extracted from an ASCII text file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 1% of the total text.

Network Working Group                                        S. Andersen

Request for Comments: 3951                           

Aalborg

University

Category: Experimental                                          A. Duric

                                                                   Telio

                                                               H. Astrom

                                                                R. Hagen

                                                               W. Kleijn

                                                               J. Linden

                                                         Global IP Sound

                                                           December 2004

                   Internet Low Bit Rate Codec (iLBC)

Status of this Memo

   This memo defines an Experimental Protocol for the Internet

   community.  It does not specify an Internet standard of any kind.

   Discussion and suggestions for improvement are requested.

   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This document specifies a speech codec suitable for robust voice

   communication over IP.  The codec is developed by Global IP Sound

   (GIPS).  It is designed for narrow band speech and results in a

   payload bit rate of 13.33 kbit/s for 30 ms frames and 15.20 kbit/s

   for 20 ms frames.  The codec enables graceful speech quality

   degradation in the case of lost frames, which occurs in connection

   with lost or delayed IP packets.

Andersen, et al.              Experimental                      [Page 1]

RFC 3951              Internet Low Bit Rate Codec          December 2004

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4

   2.  Outline of the Codec . . . . . . . . . . . . . . . . . . . . .  5

       2.1.  Encoder. . . . . . . . . . . . . . . . . . . . . . . . .  5

       2.2.  Decoder. . . . . . . . . . . . . . . . . . . . . . . . .  7

   3.  Encoder Principles . . . . . . . . . . . . . . . . . . . . . .  7

       3.1.  Pre-processing . . . . . . . . . . . . . . . . . . . . .  9

       3.2.  LPC Analysis and Quantization. . . . . . . . . . . . . .  9

             3.2.1.  Computation of Autocorrelation Coefficients. . ....