AMR Wideband Functions

The Intel IPP functions described in this section if properly combined can be used to construct the Adaptive Multi-Rate Wideband (AMR WB) Speech Codec compliant to 3rd Generation Partnership Project (3GPP) specification TS 26.173: “AMR Wideband Speech Codec; ANSI-C code". The description of AMR WB codec may be found in 3GPP TS 26.190: “AMR Wideband Speech Codec; Transcoding functions". Also it is known as ITU-T G.722.2 AMR WB codec.

The primitives are primarily designed to implement the well-defined, computationally expensive core operations that comprise the codec portion of the AMR WB system. The AMR WB codec comprises an adaptive multi-rate algorithm intended for encoding 7 kHz bandwidth speech signals at the sampling rate of 16 000 samples per second, which results in bit rates for the encoded bit stream of 6.60, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 or 23.85 kbit/s.

The list of the Intel IPP primitives for the AMR WB codec is given in the table below.

Intel IPP AMR WB Related Functions
Function Base Name	Operation
ResidualFilter_AMRWB	Computes the LPC residual
LPCToISP_AMRWB	Performs LP to ISP coefficients conversion
ISPToLPC_AMRWB	Performs ISP to LP coefficients conversion.
ISPToISF_Norm_AMRWB	Performs ISP to ISF coefficients conversion
ISFToISP_AMRWB	Performs ISF conversion to ISP
OpenLoopPitchSearch_AMRWB	Extracts an OLP lag estimate from the weighted input speech
HighPassFilterGetSize_AMRWB	Calculates the size of the high-pass filter state memory
HighPassFilterInit_AMRWB	Initializes the state memory of high-pass filter
HighPassFilter_AMRWB	Performs high-pass filtering
HighPassFilterGetDlyLine_AMRWB	Receives the parameters of delay line of high-pass filter
HighPassFilterSetDlyLine_AMRWB	Sets the parameters of delay line of high-pass filter
Preemphasize_AMRWB	Computes pre-emphasis of a speech signal
Deemphasize_AMRWB	Performs de-emphasis filtering
SynthesisFilter_AMRWB	Reconstructs the speech signal from LP coefficients and residuals
VADGetSize_AMRWB	Returns the size of the VAD module state memory
VADInit_AMRWB	Initializes the VAD module state memory
VAD_AMRWB	Performs VAD in AMR WB encoder
VADGetEnergyLevel_AMRWB	Gets the vector of energy levels from VAD memory.
AlgebraicCodebookSearch_AMRWB	Performs the fixed (algebraic) codebook search
AlgebraicCodebookDecode_AMRWB	Decodes the fixed (algebraic) codebook indexes
AdaptiveCodebookGainCoeff_AMRWB	Computes the adaptive codebook gain
AdaptiveCodebookSearch_AMRWB	Performs the adaptive codebook search
AdaptiveCodebookDecodeGetSize_AMRWB	Queries the memory length of the adaptive codebook decode module
AdaptiveCodebookDecodeInit_AMRWB	Initializes the adaptive codebook decode module memory
AdaptiveCodebookDecodeUpdate_AMRWB	Updates the adaptive codebook decode module memory
AdaptiveCodebookDecode_AMRWB	Performs the adaptive codebook decoding
ISFQuant_AMRWB	Quantizes the ISF
ISFQuantDecode_AMRWB	Decodes quantized ISFs from the received codebook index
ISFQuantDTX_AMRWB	Quantizes the ISF coefficient vector in case of DTX mode
ISFQuantDecodeDTX_AMRWB	Decodes quantized ISFs in case of DTX mode
GainQuant_AMRWB	Quantizes the adaptive codebook gains
DecodeGain_AMRWB	Decodes adaptive and fixed-codebook gains
EncDTXBuffer_AMRWB	Buffers the ISP coefficients and previous logarithm energy coefficients
DecDTXBuffer_AMRWB	Buffers the ISF coefficients and previous logarithm energy coefficients.

The use of these functions is demonstrated in the Intel IPP GSM/AMR Wideband/G.722.2 Speech Encoder-Decoder sample downloadable from http://www.intel.com/cd/software/products/asmo-na/eng/220046.htm.