For proper implementation and contextual understanding, it is essential to be aware of the other ITU-T recommendations that Annex C+ builds upon, as well as any official corrections issued after its publication. These documents provide the foundational definitions and specifications necessary for a compliant system.

6.1 Normative References

The following ITU-T Recommendations contain provisions which, through reference in this text, constitute provisions of this Recommendation.

1. ITU-T Recommendation G.729 (1996), Coding of speech at 8 kbit/s using conjugate structure algebraic code-excited linear prediction (CS-ACELP).
2. ITU-T Recommendation G.729 Annex B (1996), A silence compression scheme for G.729 optimized for terminals conforming to Recommendation V.70.
3. ITU-T Recommendation G.729 Annex C (1998), Reference floating-point implementation for G.729 CS-ACELP 8 kbit/s speech coding.
4. ITU-T Recommendation G.729 Annex D (1998), 6.4 kbit/s CS-ACELP speech coding algorithm.
5. ITU-T Recommendation G.729 Annex E (1998), 11.8 kbit/s CS-ACELP speech coding algorithm.

6.2 Corrigendum 1 (03/2001)

In July 2002, Corrigendum 1 was issued to address several editorial corrections in the original Annex C+ (02/2000) publication. These corrections clarify formulas and variable names within the text. The specific changes are as follows:

1. Location: C+.5.1, 8th line
   • Current text: Vad_dec
   • Proposed text: Vad_deci
2. Location: C+.5.1.1, in the second equation of Pitch Lag Standard Deviation (µ)
   • Current text: Summation limit is 4
   • Proposed text: Summation limit is 5
3. Location: C+.5.1.1, in the equation of Running Mean of Pitch Gain
   • Current text: Summation limit is 4
   • Proposed text: Summation limit is 5
4. Location: C+.5.1.1, 8th line in Pitch Lag Smoothness and Voicing Strength Indicator
   • Current text: if (… or (Pflag2==1))
   • Proposed text: if (… or (Pflag2 == 1))
5. Location: C+.5.1.1, last line of c) in Stationarity Counters
   • Current text: running mean, count_music
   • Proposed text: running mean of count_music

Crucially, the corrigendum explicitly states that these editorial corrections have no impact on the C-source code, which remains the normative reference.

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In summary, ITU-T Recommendation G.729 Annex C+ serves as the definitive guide for creating a unified, high-quality, and interoperable floating-point implementation of the G.729 speech codec and its multi-rate and DTX extensions.