1. Overview of ITU-T Recommendation G.729 Annex C+
1.1. Purpose and Scope
ITU-T Recommendation G.729 Annex C+ (approved 17 February 2000) serves as an extension to the previous Annex C. Its core purpose is to provide a standardized description for integrating the main G.729 speech coding algorithm with its functional Annexes B, D, and E, using floating-point arithmetic. The overarching goal is to ensure worldwide compatibility and maintain high speech quality.
The integration was designed with three primary constraints in mind:
- Bit-exactness: To remain bit-exact with the main body floating-point implementation defined in Annex C.
- Efficiency: To minimize the use of additional program code, memory, and computational complexity.
- Quality: To meet stringent quality requirements for all new functionality, particularly in the application areas covered by the integrated annexes.
1.2. Standardization Context
The recommendation falls under the ITU-T G-Series: “Transmission systems and media, digital systems and networks,” and more specifically within the G.720-G.729 sub-series covering “Coding of analogue signals by methods other than PCM.” It was prepared by ITU-T Study Group 16 (1997-2000) and approved by the World Telecommunication Standardization Conference (WTSC).
The ITU, as a United Nations Specialized Agency, draws attention to the possibility that the implementation of this standard may be protected by patents. It takes no position on the validity of any claimed Intellectual Property Rights (IPR) and states that implementors are responsible for consulting the TSB patent database.