New Annex D introduced by Amendment 5 provides an alternative implementation using floating point arithmetic of the discontinuous transmission (DTX) and comfort noise generation (CNG) of Annex C which uses fixed-point arithmetic.

Besides this new annex, Amendment 5 to Recommendation ITU-T G.729.1 incorporates changes needed to correct defects identified in the G.729.1 C source code for its main body and Annex B, and provides a revised set of test vectors.

The corrections bring changes necessary to the existing C code (Release 1.3) of the main body and Annex B of Recommendation ITU-T G.729.1. The corrected C code is labelled as Release 1.4.

For completeness, the electronic attachment to this amendment comprises:

1) Complete ANSI C source code (version 1.4) for G.729.1 main body and Annex B, including updated test vectors.

2) G.729.1 Annex D floating-point DTX/CNG ANSI C source code (version 1.4).