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217 lines
6.4 KiB
C
217 lines
6.4 KiB
C
/*
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* AC-3 DSP utils
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* Copyright (c) 2011 Justin Ruggles
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/avassert.h"
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#include "avcodec.h"
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#include "ac3.h"
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#include "ac3dsp.h"
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static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
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{
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int blk, i;
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if (!num_reuse_blocks)
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return;
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for (i = 0; i < nb_coefs; i++) {
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uint8_t min_exp = *exp;
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uint8_t *exp1 = exp + 256;
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for (blk = 0; blk < num_reuse_blocks; blk++) {
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uint8_t next_exp = *exp1;
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if (next_exp < min_exp)
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min_exp = next_exp;
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exp1 += 256;
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}
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*exp++ = min_exp;
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}
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}
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static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)
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{
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int i, v = 0;
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for (i = 0; i < len; i++)
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v |= abs(src[i]);
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return v;
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}
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static void ac3_lshift_int16_c(int16_t *src, unsigned int len,
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unsigned int shift)
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{
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uint32_t *src32 = (uint32_t *)src;
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const uint32_t mask = ~(((1 << shift) - 1) << 16);
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int i;
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len >>= 1;
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for (i = 0; i < len; i += 8) {
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src32[i ] = (src32[i ] << shift) & mask;
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src32[i+1] = (src32[i+1] << shift) & mask;
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src32[i+2] = (src32[i+2] << shift) & mask;
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src32[i+3] = (src32[i+3] << shift) & mask;
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src32[i+4] = (src32[i+4] << shift) & mask;
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src32[i+5] = (src32[i+5] << shift) & mask;
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src32[i+6] = (src32[i+6] << shift) & mask;
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src32[i+7] = (src32[i+7] << shift) & mask;
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}
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}
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static void ac3_rshift_int32_c(int32_t *src, unsigned int len,
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unsigned int shift)
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{
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do {
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*src++ >>= shift;
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*src++ >>= shift;
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*src++ >>= shift;
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*src++ >>= shift;
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*src++ >>= shift;
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*src++ >>= shift;
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*src++ >>= shift;
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*src++ >>= shift;
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len -= 8;
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} while (len > 0);
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}
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static void float_to_fixed24_c(int32_t *dst, const float *src, unsigned int len)
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{
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const float scale = 1 << 24;
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do {
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*dst++ = lrintf(*src++ * scale);
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*dst++ = lrintf(*src++ * scale);
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*dst++ = lrintf(*src++ * scale);
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*dst++ = lrintf(*src++ * scale);
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*dst++ = lrintf(*src++ * scale);
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*dst++ = lrintf(*src++ * scale);
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*dst++ = lrintf(*src++ * scale);
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*dst++ = lrintf(*src++ * scale);
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len -= 8;
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} while (len > 0);
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}
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static void ac3_bit_alloc_calc_bap_c(int16_t *mask, int16_t *psd,
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int start, int end,
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int snr_offset, int floor,
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const uint8_t *bap_tab, uint8_t *bap)
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{
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int bin, band, band_end;
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/* special case, if snr offset is -960, set all bap's to zero */
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if (snr_offset == -960) {
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memset(bap, 0, AC3_MAX_COEFS);
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return;
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}
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bin = start;
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band = ff_ac3_bin_to_band_tab[start];
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do {
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int m = (FFMAX(mask[band] - snr_offset - floor, 0) & 0x1FE0) + floor;
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band_end = ff_ac3_band_start_tab[++band];
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band_end = FFMIN(band_end, end);
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for (; bin < band_end; bin++) {
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int address = av_clip((psd[bin] - m) >> 5, 0, 63);
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bap[bin] = bap_tab[address];
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}
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} while (end > band_end);
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}
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static void ac3_update_bap_counts_c(uint16_t mant_cnt[16], uint8_t *bap,
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int len)
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{
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while (len-- > 0)
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mant_cnt[bap[len]]++;
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}
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DECLARE_ALIGNED(16, const uint16_t, ff_ac3_bap_bits)[16] = {
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0, 0, 0, 3, 0, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
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};
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static int ac3_compute_mantissa_size_c(uint16_t mant_cnt[6][16])
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{
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int blk, bap;
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int bits = 0;
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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// bap=1 : 3 mantissas in 5 bits
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bits += (mant_cnt[blk][1] / 3) * 5;
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// bap=2 : 3 mantissas in 7 bits
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// bap=4 : 2 mantissas in 7 bits
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bits += ((mant_cnt[blk][2] / 3) + (mant_cnt[blk][4] >> 1)) * 7;
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// bap=3 : 1 mantissa in 3 bits
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bits += mant_cnt[blk][3] * 3;
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// bap=5 to 15 : get bits per mantissa from table
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for (bap = 5; bap < 16; bap++)
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bits += mant_cnt[blk][bap] * ff_ac3_bap_bits[bap];
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}
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return bits;
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}
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static void ac3_extract_exponents_c(uint8_t *exp, int32_t *coef, int nb_coefs)
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{
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int i;
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for (i = 0; i < nb_coefs; i++) {
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int v = abs(coef[i]);
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exp[i] = v ? 23 - av_log2(v) : 24;
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}
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}
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static void ac3_downmix_c(float **samples, float (*matrix)[2],
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int out_ch, int in_ch, int len)
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{
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int i, j;
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float v0, v1;
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if (out_ch == 2) {
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for (i = 0; i < len; i++) {
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v0 = v1 = 0.0f;
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for (j = 0; j < in_ch; j++) {
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v0 += samples[j][i] * matrix[j][0];
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v1 += samples[j][i] * matrix[j][1];
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}
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samples[0][i] = v0;
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samples[1][i] = v1;
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}
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} else if (out_ch == 1) {
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for (i = 0; i < len; i++) {
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v0 = 0.0f;
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for (j = 0; j < in_ch; j++)
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v0 += samples[j][i] * matrix[j][0];
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samples[0][i] = v0;
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}
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}
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}
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av_cold void ff_ac3dsp_init(AC3DSPContext *c, int bit_exact)
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{
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c->ac3_exponent_min = ac3_exponent_min_c;
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c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;
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c->ac3_lshift_int16 = ac3_lshift_int16_c;
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c->ac3_rshift_int32 = ac3_rshift_int32_c;
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c->float_to_fixed24 = float_to_fixed24_c;
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c->bit_alloc_calc_bap = ac3_bit_alloc_calc_bap_c;
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c->update_bap_counts = ac3_update_bap_counts_c;
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c->compute_mantissa_size = ac3_compute_mantissa_size_c;
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c->extract_exponents = ac3_extract_exponents_c;
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c->downmix = ac3_downmix_c;
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if (ARCH_ARM)
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ff_ac3dsp_init_arm(c, bit_exact);
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if (ARCH_X86)
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ff_ac3dsp_init_x86(c, bit_exact);
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}
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