?? dec_lpc.c
字號:
isf_q[i + 5] =
(Word16)(isf_q[i + 5] + D_ROM_dico22_isf_36b[indice[3] * 4 + i]);
}
for(i = 0; i < 7; i++)
{
isf_q[i + 9] =
(Word16)(isf_q[i + 9] + D_ROM_dico23_isf_36b[indice[4] * 7 + i]);
}
for(i = 0; i < ORDER; i++)
{
tmp = isf_q[i];
isf_q[i] =
(Word16)((tmp + D_ROM_mean_isf[i]) + ((MU * past_isfq[i]) >> 15));
past_isfq[i] = tmp;
}
for(i = 0; i < M; i++)
{
for(j = (L_MEANBUF - 1); j > 0; j--)
{
isf_buf[j * M + i] = isf_buf[(j - 1) * M + i];
}
isf_buf[i] = isf_q[i];
}
}
else
{ /* bad frame */
for(i = 0; i < M; i++)
{
L_tmp = D_ROM_mean_isf[i];
for(j = 0; j < L_MEANBUF; j++)
{
L_tmp = L_tmp + isf_buf[j * M + i];
}
ref_isf[i] = (L_tmp + 0x1) >> 2;
}
/* use the past ISFs slightly shifted towards their mean */
for(i = 0; i < ORDER; i++)
{
isf_q[i] = (Word16)((((ALPHA * isfold[i]) >> 15) +
((ONE_ALPHA * ref_isf[i]) >> 15)));
}
/* estimate past quantized residual to be used in next frame */
for(i = 0; i < ORDER; i++)
{
/* predicted ISF */
L_tmp = ref_isf[i] + ((past_isfq[i] * MU) >> 15);
/* past_isfq[i] *= 0.5 */
past_isfq[i] = (Word16)((isf_q[i] - L_tmp) >> 1);
}
}
D_LPC_isf_reorder(isf_q, ISF_GAP, ORDER);
return;
}
/*
* D_LPC_isf_2s5s_decode
*
* Parameters:
* indice I: quantization indices
* isf_q O: quantized ISFs in the cosine domain
* past_isfq I/O: past ISF quantizer
* isfold I: past quantized ISF
* isf_buf O: isf buffer
* bfi I: Bad frame indicator
*
* Function:
* Decoding of ISF parameters.
*
* Returns:
* void
*/
void D_LPC_isf_2s5s_decode(Word16 *indice, Word16 *isf_q, Word16 *past_isfq,
Word16 *isfold, Word16 *isf_buf, Word16 bfi)
{
Word32 ref_isf[M];
Word32 i, j, L_tmp;
Word16 tmp;
if(bfi == 0) /* Good frame */
{
for(i = 0; i < 9; i++)
{
isf_q[i] = D_ROM_dico1_isf[indice[0] * 9 + i];
}
for(i = 0; i < 7; i++)
{
isf_q[i + 9] = D_ROM_dico2_isf[indice[1] * 7 + i];
}
for(i = 0; i < 3; i++)
{
isf_q[i] = (Word16)(isf_q[i] + D_ROM_dico21_isf[indice[2] * 3 + i]);
}
for(i = 0; i < 3; i++)
{
isf_q[i + 3] =
(Word16)(isf_q[i + 3] + D_ROM_dico22_isf[indice[3] * 3 + i]);
}
for(i = 0; i < 3; i++)
{
isf_q[i + 6] =
(Word16)(isf_q[i + 6] + D_ROM_dico23_isf[indice[4] * 3 + i]);
}
for(i = 0; i < 3; i++)
{
isf_q[i + 9] =
(Word16)(isf_q[i + 9] + D_ROM_dico24_isf[indice[5] * 3 + i]);
}
for(i = 0; i < 4; i++)
{
isf_q[i + 12] =
(Word16)(isf_q[i + 12] + D_ROM_dico25_isf[indice[6] * 4 + i]);
}
for(i = 0; i < ORDER; i++)
{
tmp = isf_q[i];
isf_q[i] =
(Word16)((tmp + D_ROM_mean_isf[i]) + ((MU * past_isfq[i]) >> 15));
past_isfq[i] = tmp;
}
for(i = 0; i < M; i++)
{
for(j = (L_MEANBUF - 1); j > 0; j--)
{
isf_buf[j * M + i] = isf_buf[(j - 1) * M + i];
}
isf_buf[i] = isf_q[i];
}
}
else
{ /* bad frame */
for(i = 0; i < M; i++)
{
L_tmp = D_ROM_mean_isf[i];
for(j = 0; j < L_MEANBUF; j++)
{
L_tmp = L_tmp + isf_buf[j * M + i];
}
ref_isf[i] = (L_tmp + 0x1) >> 2;
}
/* use the past ISFs slightly shifted towards their mean */
for(i = 0; i < ORDER; i++)
{
isf_q[i] = (Word16)(((ALPHA * isfold[i]) >> 15) +
((ONE_ALPHA * ref_isf[i]) >> 15));
}
/* estimate past quantized residual to be used in next frame */
for(i = 0; i < ORDER; i++)
{
/* predicted ISF */
L_tmp = ref_isf[i] + ((past_isfq[i] * MU) >> 15);
/* past_isfq[i] *= 0.5 */
past_isfq[i] = (Word16)((isf_q[i] - L_tmp) >> 1);
}
}
D_LPC_isf_reorder(isf_q, ISF_GAP, ORDER);
return;
}
/*
* D_LPC_int_isp_find
*
* Parameters:
* isp_old I: isps from past frame
* isp_new I: isps from present frame
* frac I: (Q15) fraction for 3 first subfr
* Az O: LP coefficients in 4 subframes
*
* Function:
* Find the interpolated ISP parameters for all subframes.
*
* Returns:
* void
*/
void D_LPC_int_isp_find(Word16 isp_old[], Word16 isp_new[],
const Word16 frac[], Word16 Az[])
{
Word32 tmp, i, k, fac_old, fac_new;
Word16 isp[M];
for(k = 0; k < 3; k++)
{
fac_new = frac[k];
fac_old = (32767 - fac_new) + 1; /* 1.0 - fac_new */
for(i = 0; i < M; i++)
{
tmp = isp_old[i] * fac_old;
tmp += isp_new[i] * fac_new;
isp[i] = (Word16)((tmp + 0x4000) >> 15);
}
D_LPC_isp_a_conversion(isp, Az, M);
Az += MP1;
}
/* 4th subframe: isp_new (frac=1.0) */
D_LPC_isp_a_conversion(isp_new, Az, M);
return;
}
/*
* D_LPC_isf_extrapolation
*
* Parameters:
* HfIsf I/O: ISF vector
*
* Function:
* Conversion of 16th-order 12.8kHz ISF vector
* into 20th-order 16kHz ISF vector
*
* Returns:
* void
*/
void D_LPC_isf_extrapolation(Word16 HfIsf[])
{
Word32 IsfDiff[M - 2];
Word32 IsfCorr[3];
Word32 tmp, tmp2, tmp3, mean, i;
Word32 MaxCorr, exp, exp2, coeff;
Word16 hi, lo;
HfIsf[M16k - 1] = HfIsf[M - 1];
/* Difference vector */
for(i = 1; i < M - 1; i++)
{
IsfDiff[i - 1] = HfIsf[i] - HfIsf[i - 1];
}
tmp = 0;
/* Mean of difference vector */
for(i = 3; i < (M - 1); i++)
{
tmp = tmp + (IsfDiff[i - 1] * INV_LENGTH);
}
mean = (tmp + 0x4000) >> 15;
IsfCorr[0] = 0;
IsfCorr[1] = 0;
IsfCorr[2] = 0;
tmp = 0;
for(i = 0; i < M - 2; i++)
{
if(IsfDiff[i] > tmp)
{
tmp = IsfDiff[i];
}
}
exp = D_UTIL_norm_s((Word16)tmp);
for(i = 0; i < M - 2; i++)
{
IsfDiff[i] = IsfDiff[i] << exp;
}
mean = mean << exp;
for(i = 7; i < M - 2; i++)
{
tmp2 = IsfDiff[i] - mean;
tmp3 = IsfDiff[i - 2] - mean;
tmp = (tmp2 * tmp3) << 1;
D_UTIL_l_extract(tmp, &hi, &lo);
tmp = D_UTIL_mpy_32(hi, lo, hi, lo);
IsfCorr[0] = (IsfCorr[0] + tmp);
}
for(i = 7; i < M - 2; i++)
{
tmp2 = IsfDiff[i] - mean;
tmp3 = IsfDiff[i - 3] - mean;
tmp = (tmp2 * tmp3) << 1;
D_UTIL_l_extract(tmp, &hi, &lo);
tmp = D_UTIL_mpy_32(hi, lo, hi, lo);
IsfCorr[1] = (IsfCorr[1] + tmp);
}
for(i = 7; i < M - 2; i++)
{
tmp2 = IsfDiff[i] - mean;
tmp3 = IsfDiff[i - 4] - mean;
tmp = (tmp2 * tmp3) << 1;
D_UTIL_l_extract(tmp, &hi, &lo);
tmp = D_UTIL_mpy_32(hi, lo, hi, lo);
IsfCorr[2] = (IsfCorr[2] + tmp);
}
if(IsfCorr[0] > IsfCorr[1])
{
MaxCorr = 0;
}
else
{
MaxCorr = 1;
}
if(IsfCorr[2] > IsfCorr[MaxCorr])
{
MaxCorr = 2;
}
MaxCorr = MaxCorr + 1; /* Maximum correlation of difference vector */
for(i = M - 1; i < (M16k - 1); i++)
{
tmp = (HfIsf[i - 1 - MaxCorr] - HfIsf[i - 2 - MaxCorr]);
HfIsf[i] = (Word16)(HfIsf[i - 1] + tmp);
}
/* tmp=7965+(HfIsf[2]-HfIsf[3]-HfIsf[4])/6; */
tmp = HfIsf[4] + HfIsf[3];
tmp = HfIsf[2] - tmp;
tmp = (tmp * 5461) >> 15;
tmp = tmp + 20390;
if(tmp > 19456)
{ /* Maximum value of ISF should be at most 7600 Hz */
tmp = 19456;
}
tmp = tmp - HfIsf[M - 2];
tmp2 = HfIsf[M16k - 2] - HfIsf[M - 2];
exp2 = D_UTIL_norm_s((Word16)tmp2);
exp = D_UTIL_norm_s((Word16)tmp);
exp = exp - 1;
tmp = tmp << exp;
tmp2 = tmp2 << exp2;
coeff = (tmp << 15) / tmp2; /* Coefficient for stretching the ISF vector */
exp = exp2 - exp;
if(exp >= 0)
{
for(i = M - 1; i < M16k - 1; i++)
{
tmp = ((HfIsf[i] - HfIsf[i - 1]) * coeff) >> 15;
IsfDiff[i - (M - 1)] = tmp << exp;
}
}
else
{
exp = 15 - exp;
for(i = M - 1; i < M16k - 1; i++)
{
IsfDiff[i - (M - 1)] = ((HfIsf[i] - HfIsf[i - 1]) * coeff) >> exp;
}
}
for(i = M; i < (M16k - 1); i++)
{
/* The difference between ISF(n) and ISF(n-2) should be at least 500 Hz */
tmp = ((IsfDiff[i - (M - 1)] + IsfDiff[i - M]) - 1280);
if(tmp < 0)
{
if(IsfDiff[i - (M - 1)] > IsfDiff[i - M])
{
IsfDiff[i - M] = (1280 - IsfDiff[i - (M - 1)]);
}
else
{
IsfDiff[i - (M - 1)] = (1280 - IsfDiff[i - M]);
}
}
}
for(i = M - 1; i < M16k - 1; i++)
{
HfIsf[i] = (Word16)(HfIsf[i - 1] + IsfDiff[i - (M - 1)]);
}
for(i = 0; i < M16k - 1; i++)
{
HfIsf[i] = (Word16)((HfIsf[i] * 13107) >> 14);
/* Scale the ISF vector correctly for 16000 kHz */
}
D_LPC_isf_isp_conversion(HfIsf, HfIsf, M16k);
return;
}
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