ITU-T Recommendations

This Recommendation provides source code for speech and audio processing modules for narrowband, wideband and super-wideband telephony applications. The set includes codecs, filters, noise generators, etc.

This revision introduces changes to ITU-T G.191 Annex A, which describes the ITU-T Software Tools (STL) containing a high-quality, portable C code library for speech processing applications.
This new release of the STL, also known as STL2019, incorporates new basic operators to accommodate state-of-the-art processor architectures which supports wide accumulators, SIMD (Single Instruction Multiple Data) and VLIW (Very Long Instruction Word). Thus the new operators provides support for 64-bit accumulator, complex numbers, enhanced 32-bit operations and additional control code operators.

The software package was reworked to make it available as a truly open-source project and is therefore hosted on an open-source collaboration platform. The build toolchain is now using CMake to generate platform-dependent and tool-dependent build scripts as well as to execute regression tests for each module in the STL.

This Recommendation includes an electronic attachment containing STL2019 Software Tool Library and manual.