Decodes the global TCX gain.
Syntax
IppStatus ippsGainDecodeTCX_AMRWBE_16s(const Ipp16s* pSrcQuantSignal, int len, Ipp16s quantIdx, Ipp32s bfi, Ipp16s* pSrcDstRMSval, Ipp32s* pGain);
Parameters
pSrcQuantSignal |
Pointer to the quantized signal. |
len |
Length of the source signal. |
quantIdx |
Index of quantization. |
bfi |
Bad frame indicator. Value "0" signifies a good frame; any other value signifies a bad frame. |
pSrcDstRMSval |
Pointer to the root mean square value. |
pGain |
Pointer to the output global TCX gain. |
Description
The function ippsGainDecodeTCX_AMRWBE is declared in ippsc.h file. This function decodes the global TCX gain gTCX by inverting the 7-bit logarithmic quantization calculated in the TCX encoder as in the function ippsGainQuantTCX_AMRWBE.
First the RMS value of the TCX target signal pSrcQuantSignal(x') is computed as
From the received 7-bit index 0 ≤ quantIdx ≤ 127, the TCX gain pGain can be computed
pGain* = 10quantIdx/28*4rms
See also 3GPP TS 26.290: “Extended AMR Wideband Speech Codec; Transcoding functions", clause 6.1.2 [AMRWB+].
Return Values
ippStsNoErr |
Indicates no error. |
ippStsNullPtrErr |
Indicates an error when one of the specified pointer is NULL. |
ippStsSizeErr |
Indicates an error when len is less than or equal to zero. |