The EVS coder (TS 26.441
) provides enhanced quality for speech and audio communications relative to AMR-WB and 3GPP has standardized both a fixed-point version (TS 26.442
) and a floating-point version (TS 26.443
). Currently in TS 26.444
(Codec for Enhanced Voice Services (EVS); Test sequences) the conformance of the EVS coder implementation is achieved by checking the bit-exactness of output test vectors with the reference test vectors for both encoder and decoder, for both the fixed-point and floating-point implementations.
The bit-exact criteria defined in TS 26.444
are of very limited use for the floating-point implementation in TS 26.443
as the output values will be similar but not bit-exact for different compilers, compile options, OS and platform used and therefore failing the bit-exactness test.
This technical report aims at documenting possible methods for non bit-exact conformance process for floating-point implementation that would allow conforming implementations to be used in all scenarios acceptable for bit-exact implementations of fixed-point version (TS 26.442
) and floating-point version (TS 26.443
The scope of the study item is to assess the use of various floating-point processing cores and compilers with various levels of optimization, and establish potential conformance criteria and a tool(s) that could be used for confirming conformance under those variations. The scope of the intended conformance tool(s) is to assess the conformance of implementations to the developed criteria. The conformance criteria to be developed will aim at accepting proper floating-point processing compute core and compiler optimizations, while rejecting all bad implementations, for example coming from functional or code changes, too aggressive optimization of the compiler or insufficient arithmetic precision.
In Clause 5
various methods are described.
In Clause 6
results obtained with the various methods described in Clause 5
In Clause 7
possible conformance process and criteria are discussed.
Interoperability is an important feature of the coder, and implication for non bit-exact conformance will be investigated in Clause 8
will look at coverage of the proposed method.
will address any other topics relevant to the context of this study.
Clause 11 will conclude on the feasibility of using non bit-exact tools and criteria for EVS floating point conformance.