ETSI has produced several recommendations for the coding of speech, for example, the G.723.1 and G.729 recommendations. These recommendations include source code and test sequences for reference implementations of the codecs.
Model implementations of speech codecs supplied by ETSI are based on a collection of C functions known as the ETSI basic operations. The ETSI basic operations include 16-bit, 32-bit and 40-bit operations for saturated arithmetic, 16-bit and 32-bit logical operations, and 16-bit and 32-bit operations for data type conversion.
Version 2.0 of the ETSI collection of basic operations, as described in the ITU-T Software Tool Library 2005 User's manual, introduces new 16-bit, 32-bit and 40 bit-operations. These operations are not supported in the ARM compilation tools.
The ETSI basic operations serve as a set of primitives for developers publishing codec algorithms, rather than as a library for use by developers implementing codecs in C or C++.
- Other information
ETSI Recommendation G.191: Software tools for speech and audio coding standardization
ITU-T Software Tool Library 2005 User's manual, included as part of ETSI Recommendation G.191
ETSI Recommendation G723.1: Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s
ETSI Recommendation G.729: Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP).