150 lines
5.5 KiB
C
150 lines
5.5 KiB
C
/* L3mdct */
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#include "l3mdct.h"
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#include "l3subband.h"
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#include "types.h"
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/* This is table B.9: coefficients for aliasing reduction */
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#define MDCT_CA(coef) (int32_t)(coef / sqrt(1.0 + (coef * coef)) * 0x7fffffff)
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#define MDCT_CS(coef) (int32_t)(1.0 / sqrt(1.0 + (coef * coef)) * 0x7fffffff)
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#define MDCT_CA0 MDCT_CA(-0.6)
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#define MDCT_CA1 MDCT_CA(-0.535)
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#define MDCT_CA2 MDCT_CA(-0.33)
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#define MDCT_CA3 MDCT_CA(-0.185)
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#define MDCT_CA4 MDCT_CA(-0.095)
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#define MDCT_CA5 MDCT_CA(-0.041)
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#define MDCT_CA6 MDCT_CA(-0.0142)
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#define MDCT_CA7 MDCT_CA(-0.0037)
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#define MDCT_CS0 MDCT_CS(-0.6)
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#define MDCT_CS1 MDCT_CS(-0.535)
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#define MDCT_CS2 MDCT_CS(-0.33)
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#define MDCT_CS3 MDCT_CS(-0.185)
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#define MDCT_CS4 MDCT_CS(-0.095)
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#define MDCT_CS5 MDCT_CS(-0.041)
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#define MDCT_CS6 MDCT_CS(-0.0142)
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#define MDCT_CS7 MDCT_CS(-0.0037)
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/*
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* shine_mdct_initialise:
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* -------------------
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*/
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void shine_mdct_initialise(shine_global_config *config) {
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int m, k;
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/* prepare the mdct coefficients */
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for (m = 18; m--;)
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for (k = 36; k--;)
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/* combine window and mdct coefficients into a single table */
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/* scale and convert to fixed point before storing */
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config->mdct.cos_l[m][k] =
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(int32_t)(sin(PI36 * (k + 0.5)) *
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cos((PI / 72) * (2 * k + 19) * (2 * m + 1)) * 0x7fffffff);
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}
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/*
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* shine_mdct_sub:
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* ------------
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*/
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void shine_mdct_sub(shine_global_config *config, int stride) {
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/* note. we wish to access the array 'config->mdct_freq[2][2][576]' as
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* [2][2][32][18]. (32*18=576),
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*/
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int32_t(*mdct_enc)[18];
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int ch, gr, band, j, k;
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int32_t mdct_in[36];
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for (ch = config->wave.channels; ch--;) {
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for (gr = 0; gr < config->mpeg.granules_per_frame; gr++) {
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/* set up pointer to the part of config->mdct_freq we're using */
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mdct_enc = (int32_t(*)[18])config->mdct_freq[ch][gr];
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/* polyphase filtering */
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for (k = 0; k < 18; k += 2) {
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shine_window_filter_subband(&config->buffer[ch],
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&config->l3_sb_sample[ch][gr + 1][k][0], ch,
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config, stride);
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shine_window_filter_subband(&config->buffer[ch],
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&config->l3_sb_sample[ch][gr + 1][k + 1][0],
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ch, config, stride);
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/* Compensate for inversion in the analysis filter
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* (every odd index of band AND k)
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*/
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for (band = 1; band < 32; band += 2)
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config->l3_sb_sample[ch][gr + 1][k + 1][band] *= -1;
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}
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/* Perform imdct of 18 previous subband samples + 18 current subband
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* samples */
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for (band = 0; band < 32; band++) {
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for (k = 18; k--;) {
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mdct_in[k] = config->l3_sb_sample[ch][gr][k][band];
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mdct_in[k + 18] = config->l3_sb_sample[ch][gr + 1][k][band];
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}
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/* Calculation of the MDCT
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* In the case of long blocks ( block_type 0,1,3 ) there are
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* 36 coefficients in the time domain and 18 in the frequency
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* domain.
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*/
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for (k = 18; k--;) {
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int32_t vm;
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#ifdef __BORLANDC__
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uint32_t vm_lo;
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#else
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uint32_t vm_lo __attribute__((unused));
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#endif
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mul0(vm, vm_lo, mdct_in[35], config->mdct.cos_l[k][35]);
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for (j = 35; j; j -= 7) {
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muladd(vm, vm_lo, mdct_in[j - 1], config->mdct.cos_l[k][j - 1]);
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muladd(vm, vm_lo, mdct_in[j - 2], config->mdct.cos_l[k][j - 2]);
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muladd(vm, vm_lo, mdct_in[j - 3], config->mdct.cos_l[k][j - 3]);
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muladd(vm, vm_lo, mdct_in[j - 4], config->mdct.cos_l[k][j - 4]);
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muladd(vm, vm_lo, mdct_in[j - 5], config->mdct.cos_l[k][j - 5]);
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muladd(vm, vm_lo, mdct_in[j - 6], config->mdct.cos_l[k][j - 6]);
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muladd(vm, vm_lo, mdct_in[j - 7], config->mdct.cos_l[k][j - 7]);
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}
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mulz(vm, vm_lo);
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mdct_enc[band][k] = vm;
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}
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/* Perform aliasing reduction butterfly */
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if (band != 0) {
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cmuls(mdct_enc[band][0], mdct_enc[band - 1][17 - 0],
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mdct_enc[band][0], mdct_enc[band - 1][17 - 0], MDCT_CS0,
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MDCT_CA0);
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cmuls(mdct_enc[band][1], mdct_enc[band - 1][17 - 1],
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mdct_enc[band][1], mdct_enc[band - 1][17 - 1], MDCT_CS1,
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MDCT_CA1);
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cmuls(mdct_enc[band][2], mdct_enc[band - 1][17 - 2],
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mdct_enc[band][2], mdct_enc[band - 1][17 - 2], MDCT_CS2,
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MDCT_CA2);
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cmuls(mdct_enc[band][3], mdct_enc[band - 1][17 - 3],
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mdct_enc[band][3], mdct_enc[band - 1][17 - 3], MDCT_CS3,
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MDCT_CA3);
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cmuls(mdct_enc[band][4], mdct_enc[band - 1][17 - 4],
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mdct_enc[band][4], mdct_enc[band - 1][17 - 4], MDCT_CS4,
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MDCT_CA4);
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cmuls(mdct_enc[band][5], mdct_enc[band - 1][17 - 5],
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mdct_enc[band][5], mdct_enc[band - 1][17 - 5], MDCT_CS5,
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MDCT_CA5);
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cmuls(mdct_enc[band][6], mdct_enc[band - 1][17 - 6],
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mdct_enc[band][6], mdct_enc[band - 1][17 - 6], MDCT_CS6,
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MDCT_CA6);
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cmuls(mdct_enc[band][7], mdct_enc[band - 1][17 - 7],
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mdct_enc[band][7], mdct_enc[band - 1][17 - 7], MDCT_CS7,
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MDCT_CA7);
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}
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}
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}
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/* Save latest granule's subband samples to be used in the next mdct call */
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memcpy(config->l3_sb_sample[ch][0],
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config->l3_sb_sample[ch][config->mpeg.granules_per_frame],
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sizeof(config->l3_sb_sample[0][0]));
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}
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}
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