4.0 Analysis of Corrigendum 1 (03/2001)
Standards are living documents that are often refined to correct errors or clarify ambiguities. Corrigendum 1 for Annex C+ serves as an official update to the standard’s textual description.
A covering note for the corrigendum, dated 3 July 2002, clarifies that the changes originated from discussions at the SG 16 meeting held in Geneva from 13-17 November 2000. For any implementor or user of the standard, the most critical takeaway from this update is explicitly stated:
“These editorial corrections have no impact on the C-source code.”
The corrigendum details five specific corrections to the text of the recommendation. These are summarized below:
| No. | Location in Annex C+ Text | Previous Text | Corrected Text |
| 1 | C+.5.1, 8th line | Vad_dec | Vad_deci |
| 2 | C+.5.1.1, in the second equation of Pitch Lag Standard Deviation | Summation using index L (Σ from L=1 to 5) | Summation using index i (Σ from i=1 to 5) |
| 3 | C+.5.1.1, in the equation of Running Mean of Pitch Gain | Summation using index L (Σ from L=1 to 5) | Summation using index i (Σ from i=1 to 5) |
| 4 | C+.5.1.1, 8th line in Pitch Lag Smoothness and Voicing Strength Indicator | if (… or (Pflag2==1)) | if (… or (Pflag2 == 1)) |
| 5 | C+.5.1.1, last line of c) in Stationarity Counters | running mean, count_music | running mean of count_music |
The practical impact of this corrigendum is one of clarification, not functional change. The corrections resolve minor typographical and syntactical errors in the descriptive text and mathematical formulas. By confirming that these changes had no effect on the reference C source code, the ITU ensured continuity for the industry. Software already implemented according to the reference code remained fully compliant, preventing unnecessary and costly rework for existing deployments while improving the clarity of the standard for all future implementors. This focus on textual clarification rather than code modification ensured that the standard remained stable, protecting existing intellectual property implementations and investments across the industry.