/* Upsample by a factor 2, coarser */
void SKP_Silk_resample_2_1_coarse(
const SKP_int16 *in, /* I: 8 kHz signal [len] */
SKP_int32 *S, /* I/O: State vector [4] */
SKP_int16 *out, /* O: 16 kHz signal [2*len] */
SKP_int32 *scratch, /* I: Scratch memory [3*len] */
const SKP_int32 len /* I: Number of INPUT samples */
)
{
SKP_int32 k, idx;
/* Coefficients for coarser 2-fold resampling */
const SKP_int16 A20c[ 2 ] = { 2119, 16663 };
const SKP_int16 A21c[ 2 ] = { 8050, 26861 };
/* Convert Q15 -> Q25 */
for( k = 0; k < len; k++ ) {
scratch[ k ] = SKP_LSHIFT( (SKP_int32)in[ k ], 10 );
}
idx = SKP_LSHIFT( len, 1 );
/* Allpass filters */
SKP_Silk_allpass_int( scratch, S, A20c[ 0 ], scratch + idx, len );
SKP_Silk_allpass_int( scratch + idx, S + 1, A20c[ 1 ], scratch + len, len );
SKP_Silk_allpass_int( scratch, S + 2, A21c[ 0 ], scratch + idx, len );
SKP_Silk_allpass_int( scratch + idx, S + 3, A21c[ 1 ], scratch, len );
/* Interleave two allpass outputs */
for( k = 0; k < len; k++ ) {
idx = SKP_LSHIFT( k, 1 );
out[ idx ] = (SKP_int16)SKP_SAT16( SKP_RSHIFT_ROUND( scratch[ k + len ], 10 ) );
out[ idx + 1 ] = (SKP_int16)SKP_SAT16( SKP_RSHIFT_ROUND( scratch[ k ], 10 ) );
}
}
/* Downsample by a factor 2, coarsest */
void SKP_Silk_resample_1_2_coarsest(
const SKP_int16 *in, /* I: 16 kHz signal [2*len] */
SKP_int32 *S, /* I/O: State vector [2] */
SKP_int16 *out, /* O: 8 kHz signal [len] */
SKP_int32 *scratch, /* I: Scratch memory [3*len] */
const SKP_int32 len /* I: Number of OUTPUT samples*/
)
{
SKP_int32 k, idx;
/* De-interleave allpass inputs, and convert Q15 -> Q25 */
for( k = 0; k < len; k++ ) {
idx = SKP_LSHIFT( k, 1 );
scratch[ k ] = SKP_LSHIFT( (SKP_int32)in[ idx ], 10 );
scratch[ k + len ] = SKP_LSHIFT( (SKP_int32)in[ idx + 1 ], 10 );
}
idx = SKP_LSHIFT( len, 1 );
/* Allpass filters */
SKP_Silk_allpass_int( scratch, S, A21cst[ 0 ], scratch + idx, len );
SKP_Silk_allpass_int( scratch + len, S + 1, A20cst[ 0 ], scratch, len );
/* Add two allpass outputs */
for( k = 0; k < len; k++ ) {
out[ k ] = (SKP_int16)SKP_SAT16( SKP_RSHIFT_ROUND( scratch[ k ] + scratch[ k + idx ], 11 ) );
}
}
/* Split signal into two decimated bands using first-order allpass filters */
void SKP_Silk_ana_filt_bank_1(const int16_t * in, /* I: Input signal [N] */
int32_t * S, /* I/O: State vector [2] */
int16_t * outL, /* O: Low band [N/2] */
int16_t * outH, /* O: High band [N/2] */
int32_t * scratch, /* I: Scratch memory [3*N/2] */
const int32_t N /* I: Number of input samples */
)
{
int k, N2 = SKP_RSHIFT(N, 1);
int32_t out_tmp;
/* De-interleave three allpass inputs, and convert Q15 -> Q25 */
for (k = 0; k < N2; k++) {
scratch[k + N] = SKP_LSHIFT((int32_t) in[2 * k], 10);
scratch[k + N2] = SKP_LSHIFT((int32_t) in[2 * k + 1], 10);
}
/* Allpass filters */
SKP_Silk_allpass_int(scratch + N2, S + 0, A_fb1_20[0], scratch, N2);
SKP_Silk_allpass_int(scratch + N, S + 1, A_fb1_21[0], scratch + N2, N2);
/* Add and subtract two allpass outputs to create bands */
for (k = 0; k < N2; k++) {
out_tmp = scratch[k] + scratch[k + N2];
outL[k] = (int16_t) SKP_SAT16(SKP_RSHIFT_ROUND(out_tmp, 11));
out_tmp = scratch[k] - scratch[k + N2];
outH[k] = (int16_t) SKP_SAT16(SKP_RSHIFT_ROUND(out_tmp, 11));
}
}
/* Resamples by a factor 3/1 */
void SKP_Silk_resample_3_1(
SKP_int16 *out, /* O: Fs_high signal [inLen*3] */
SKP_int32 *S, /* I/O: State vector [7] */
const SKP_int16 *in, /* I: Fs_low signal [inLen] */
const SKP_int32 inLen /* I: Input length */
)
{
SKP_int k, LSubFrameIn, LSubFrameOut;
SKP_int32 out_tmp, idx, inLenTmp = inLen;
SKP_int32 scratch00[ IN_SUBFR_LEN_RESAMPLE_3_1 ];
SKP_int32 scratch0[ 3 * IN_SUBFR_LEN_RESAMPLE_3_1 ];
SKP_int32 scratch1[ 3 * IN_SUBFR_LEN_RESAMPLE_3_1 ];
/* Coefficients for 3-fold resampling */
const SKP_int16 A30[ 2 ] = { 1773, 17818 };
const SKP_int16 A31[ 2 ] = { 4942, 25677 };
const SKP_int16 A32[ 2 ] = { 11786, 29304 };
while( inLenTmp > 0 ) {
LSubFrameIn = SKP_min_int( IN_SUBFR_LEN_RESAMPLE_3_1, inLenTmp );
LSubFrameOut = SKP_SMULBB( 3, LSubFrameIn );
/* Convert Q15 -> Q25 */
for( k = 0; k < LSubFrameIn; k++ ) {
scratch00[k] = SKP_LSHIFT( (SKP_int32)in[ k ], 10 );
}
/* Allpass filtering */
/* Scratch size: 2 * 3* LSubFrame * sizeof(SKP_int32) */
SKP_Silk_allpass_int( scratch00, S + 1, A30[ 0 ], scratch1, LSubFrameIn );
SKP_Silk_allpass_int( scratch1, S + 2, A30[ 1 ], scratch0, LSubFrameIn );
SKP_Silk_allpass_int( scratch00, S + 3, A31[ 0 ], scratch1, LSubFrameIn );
SKP_Silk_allpass_int( scratch1, S + 4, A31[ 1 ], scratch0 + IN_SUBFR_LEN_RESAMPLE_3_1, LSubFrameIn );
SKP_Silk_allpass_int( scratch00, S + 5, A32[ 0 ], scratch1, LSubFrameIn );
SKP_Silk_allpass_int( scratch1, S + 6, A32[ 1 ], scratch0 + 2 * IN_SUBFR_LEN_RESAMPLE_3_1, LSubFrameIn );
/* Interleave three allpass outputs */
for( k = 0; k < LSubFrameIn; k++ ) {
idx = SKP_SMULBB( 3, k );
scratch1[ idx ] = scratch0[ k ];
scratch1[ idx + 1 ] = scratch0[ k + IN_SUBFR_LEN_RESAMPLE_3_1 ];
scratch1[ idx + 2 ] = scratch0[ k + 2 * IN_SUBFR_LEN_RESAMPLE_3_1 ];
}
/* Low-pass filtering */
SKP_Silk_lowpass_int( scratch1, S, scratch0, LSubFrameOut );
/* Saturate and convert to SKP_int16 */
for( k = 0; k < LSubFrameOut; k++ ) {
out_tmp = scratch0[ k ];
out[ k ] = (SKP_int16) SKP_SAT16( SKP_RSHIFT_ROUND( out_tmp, 10 ) );
}
in += LSubFrameIn;
inLenTmp -= LSubFrameIn;
out += LSubFrameOut;
}
}
/* Downsamples by a factor 3 */
void SKP_Silk_resample_1_3(
SKP_int16 *out, /* O: Fs_low signal [inLen/3] */
SKP_int32 *S, /* I/O: State vector [7] */
const SKP_int16 *in, /* I: Fs_high signal [inLen] */
const SKP_int32 inLen /* I: Input length, must be a multiple of 3 */
)
{
SKP_int k, outLen, LSubFrameIn, LSubFrameOut;
SKP_int32 out_tmp, limit = 102258000; // (102258000 + 1560) * 21 * 2^(-16) = 32767.5
SKP_int32 scratch0[ 3 * OUT_SUBFR_LEN ];
SKP_int32 scratch10[ OUT_SUBFR_LEN ], scratch11[ OUT_SUBFR_LEN ], scratch12[ OUT_SUBFR_LEN ];
/* coefficients for 3-fold resampling */
const SKP_int16 A30[ 2 ] = { 1773, 17818 };
const SKP_int16 A31[ 2 ] = { 4942, 25677 };
const SKP_int16 A32[ 2 ] = { 11786, 29304 };
/* Check that input is multiple of 3 */
SKP_assert( inLen % 3 == 0 );
outLen = SKP_DIV32_16( inLen, 3 );
while( outLen > 0 ) {
LSubFrameOut = SKP_min_int( OUT_SUBFR_LEN, outLen );
LSubFrameIn = SKP_SMULBB( 3, LSubFrameOut );
/* Low-pass filter, Q15 -> Q25 */
SKP_Silk_lowpass_short( in, S, scratch0, LSubFrameIn );
/* De-interleave three allpass inputs */
for( k = 0; k < LSubFrameOut; k++ ) {
scratch10[ k ] = scratch0[ 3 * k ];
scratch11[ k ] = scratch0[ 3 * k + 1 ];
scratch12[ k ] = scratch0[ 3 * k + 2 ];
}
/* Allpass filters */
SKP_Silk_allpass_int( scratch10, S + 1, A32[ 0 ], scratch0, LSubFrameOut );
SKP_Silk_allpass_int( scratch0, S + 2, A32[ 1 ], scratch10, LSubFrameOut );
SKP_Silk_allpass_int( scratch11, S + 3, A31[ 0 ], scratch0, LSubFrameOut );
SKP_Silk_allpass_int( scratch0, S + 4, A31[ 1 ], scratch11, LSubFrameOut );
SKP_Silk_allpass_int( scratch12, S + 5, A30[ 0 ], scratch0, LSubFrameOut );
SKP_Silk_allpass_int( scratch0, S + 6, A30[ 1 ], scratch12, LSubFrameOut );
/* Add three allpass outputs */
for( k = 0; k < LSubFrameOut; k++ ) {
out_tmp = scratch10[ k ] + scratch11[ k ] + scratch12[ k ];
if( out_tmp - limit > 0 ) {
out[ k ] = SKP_int16_MAX;
} else if( out_tmp + limit < 0 ) {
out[ k ] = SKP_int16_MIN;
} else {
out[ k ] = (SKP_int16) SKP_SMULWB( out_tmp + 1560, 21 );
}
}
in += LSubFrameIn;
out += LSubFrameOut;
outLen -= LSubFrameOut;
}
}
