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  1. /*
  2.  * AC-3 DSP utils
  3.  * Copyright (c) 2011 Justin Ruggles
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include "libavutil/avassert.h"
  23. #include "avcodec.h"
  24. #include "ac3.h"
  25. #include "ac3dsp.h"
  26. #include "mathops.h"
  27.  
  28. static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
  29. {
  30.     int blk, i;
  31.  
  32.     if (!num_reuse_blocks)
  33.         return;
  34.  
  35.     for (i = 0; i < nb_coefs; i++) {
  36.         uint8_t min_exp = *exp;
  37.         uint8_t *exp1 = exp + 256;
  38.         for (blk = 0; blk < num_reuse_blocks; blk++) {
  39.             uint8_t next_exp = *exp1;
  40.             if (next_exp < min_exp)
  41.                 min_exp = next_exp;
  42.             exp1 += 256;
  43.         }
  44.         *exp++ = min_exp;
  45.     }
  46. }
  47.  
  48. static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)
  49. {
  50.     int i, v = 0;
  51.     for (i = 0; i < len; i++)
  52.         v |= abs(src[i]);
  53.     return v;
  54. }
  55.  
  56. static void ac3_lshift_int16_c(int16_t *src, unsigned int len,
  57.                                unsigned int shift)
  58. {
  59.     uint32_t *src32 = (uint32_t *)src;
  60.     const uint32_t mask = ~(((1 << shift) - 1) << 16);
  61.     int i;
  62.     len >>= 1;
  63.     for (i = 0; i < len; i += 8) {
  64.         src32[i  ] = (src32[i  ] << shift) & mask;
  65.         src32[i+1] = (src32[i+1] << shift) & mask;
  66.         src32[i+2] = (src32[i+2] << shift) & mask;
  67.         src32[i+3] = (src32[i+3] << shift) & mask;
  68.         src32[i+4] = (src32[i+4] << shift) & mask;
  69.         src32[i+5] = (src32[i+5] << shift) & mask;
  70.         src32[i+6] = (src32[i+6] << shift) & mask;
  71.         src32[i+7] = (src32[i+7] << shift) & mask;
  72.     }
  73. }
  74.  
  75. static void ac3_rshift_int32_c(int32_t *src, unsigned int len,
  76.                                unsigned int shift)
  77. {
  78.     do {
  79.         *src++ >>= shift;
  80.         *src++ >>= shift;
  81.         *src++ >>= shift;
  82.         *src++ >>= shift;
  83.         *src++ >>= shift;
  84.         *src++ >>= shift;
  85.         *src++ >>= shift;
  86.         *src++ >>= shift;
  87.         len -= 8;
  88.     } while (len > 0);
  89. }
  90.  
  91. static void float_to_fixed24_c(int32_t *dst, const float *src, unsigned int len)
  92. {
  93.     const float scale = 1 << 24;
  94.     do {
  95.         *dst++ = lrintf(*src++ * scale);
  96.         *dst++ = lrintf(*src++ * scale);
  97.         *dst++ = lrintf(*src++ * scale);
  98.         *dst++ = lrintf(*src++ * scale);
  99.         *dst++ = lrintf(*src++ * scale);
  100.         *dst++ = lrintf(*src++ * scale);
  101.         *dst++ = lrintf(*src++ * scale);
  102.         *dst++ = lrintf(*src++ * scale);
  103.         len -= 8;
  104.     } while (len > 0);
  105. }
  106.  
  107. static void ac3_bit_alloc_calc_bap_c(int16_t *mask, int16_t *psd,
  108.                                      int start, int end,
  109.                                      int snr_offset, int floor,
  110.                                      const uint8_t *bap_tab, uint8_t *bap)
  111. {
  112.     int bin, band, band_end;
  113.  
  114.     /* special case, if snr offset is -960, set all bap's to zero */
  115.     if (snr_offset == -960) {
  116.         memset(bap, 0, AC3_MAX_COEFS);
  117.         return;
  118.     }
  119.  
  120.     bin  = start;
  121.     band = ff_ac3_bin_to_band_tab[start];
  122.     do {
  123.         int m = (FFMAX(mask[band] - snr_offset - floor, 0) & 0x1FE0) + floor;
  124.         band_end = ff_ac3_band_start_tab[++band];
  125.         band_end = FFMIN(band_end, end);
  126.  
  127.         for (; bin < band_end; bin++) {
  128.             int address = av_clip((psd[bin] - m) >> 5, 0, 63);
  129.             bap[bin] = bap_tab[address];
  130.         }
  131.     } while (end > band_end);
  132. }
  133.  
  134. static void ac3_update_bap_counts_c(uint16_t mant_cnt[16], uint8_t *bap,
  135.                                     int len)
  136. {
  137.     while (len-- > 0)
  138.         mant_cnt[bap[len]]++;
  139. }
  140.  
  141. DECLARE_ALIGNED(16, const uint16_t, ff_ac3_bap_bits)[16] = {
  142.     0,  0,  0,  3,  0,  4,  5,  6,  7,  8,  9, 10, 11, 12, 14, 16
  143. };
  144.  
  145. static int ac3_compute_mantissa_size_c(uint16_t mant_cnt[6][16])
  146. {
  147.     int blk, bap;
  148.     int bits = 0;
  149.  
  150.     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
  151.         // bap=1 : 3 mantissas in 5 bits
  152.         bits += (mant_cnt[blk][1] / 3) * 5;
  153.         // bap=2 : 3 mantissas in 7 bits
  154.         // bap=4 : 2 mantissas in 7 bits
  155.         bits += ((mant_cnt[blk][2] / 3) + (mant_cnt[blk][4] >> 1)) * 7;
  156.         // bap=3 : 1 mantissa in 3 bits
  157.         bits += mant_cnt[blk][3] * 3;
  158.         // bap=5 to 15 : get bits per mantissa from table
  159.         for (bap = 5; bap < 16; bap++)
  160.             bits += mant_cnt[blk][bap] * ff_ac3_bap_bits[bap];
  161.     }
  162.     return bits;
  163. }
  164.  
  165. static void ac3_extract_exponents_c(uint8_t *exp, int32_t *coef, int nb_coefs)
  166. {
  167.     int i;
  168.  
  169.     for (i = 0; i < nb_coefs; i++) {
  170.         int v = abs(coef[i]);
  171.         exp[i] = v ? 23 - av_log2(v) : 24;
  172.     }
  173. }
  174.  
  175. static void ac3_sum_square_butterfly_int32_c(int64_t sum[4],
  176.                                              const int32_t *coef0,
  177.                                              const int32_t *coef1,
  178.                                              int len)
  179. {
  180.     int i;
  181.  
  182.     sum[0] = sum[1] = sum[2] = sum[3] = 0;
  183.  
  184.     for (i = 0; i < len; i++) {
  185.         int lt = coef0[i];
  186.         int rt = coef1[i];
  187.         int md = lt + rt;
  188.         int sd = lt - rt;
  189.         MAC64(sum[0], lt, lt);
  190.         MAC64(sum[1], rt, rt);
  191.         MAC64(sum[2], md, md);
  192.         MAC64(sum[3], sd, sd);
  193.     }
  194. }
  195.  
  196. static void ac3_sum_square_butterfly_float_c(float sum[4],
  197.                                              const float *coef0,
  198.                                              const float *coef1,
  199.                                              int len)
  200. {
  201.     int i;
  202.  
  203.     sum[0] = sum[1] = sum[2] = sum[3] = 0;
  204.  
  205.     for (i = 0; i < len; i++) {
  206.         float lt = coef0[i];
  207.         float rt = coef1[i];
  208.         float md = lt + rt;
  209.         float sd = lt - rt;
  210.         sum[0] += lt * lt;
  211.         sum[1] += rt * rt;
  212.         sum[2] += md * md;
  213.         sum[3] += sd * sd;
  214.     }
  215. }
  216.  
  217. static void ac3_downmix_c(float **samples, float (*matrix)[2],
  218.                           int out_ch, int in_ch, int len)
  219. {
  220.     int i, j;
  221.     float v0, v1;
  222.     if (out_ch == 2) {
  223.         for (i = 0; i < len; i++) {
  224.             v0 = v1 = 0.0f;
  225.             for (j = 0; j < in_ch; j++) {
  226.                 v0 += samples[j][i] * matrix[j][0];
  227.                 v1 += samples[j][i] * matrix[j][1];
  228.             }
  229.             samples[0][i] = v0;
  230.             samples[1][i] = v1;
  231.         }
  232.     } else if (out_ch == 1) {
  233.         for (i = 0; i < len; i++) {
  234.             v0 = 0.0f;
  235.             for (j = 0; j < in_ch; j++)
  236.                 v0 += samples[j][i] * matrix[j][0];
  237.             samples[0][i] = v0;
  238.         }
  239.     }
  240. }
  241.  
  242. av_cold void ff_ac3dsp_init(AC3DSPContext *c, int bit_exact)
  243. {
  244.     c->ac3_exponent_min = ac3_exponent_min_c;
  245.     c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;
  246.     c->ac3_lshift_int16 = ac3_lshift_int16_c;
  247.     c->ac3_rshift_int32 = ac3_rshift_int32_c;
  248.     c->float_to_fixed24 = float_to_fixed24_c;
  249.     c->bit_alloc_calc_bap = ac3_bit_alloc_calc_bap_c;
  250.     c->update_bap_counts = ac3_update_bap_counts_c;
  251.     c->compute_mantissa_size = ac3_compute_mantissa_size_c;
  252.     c->extract_exponents = ac3_extract_exponents_c;
  253.     c->sum_square_butterfly_int32 = ac3_sum_square_butterfly_int32_c;
  254.     c->sum_square_butterfly_float = ac3_sum_square_butterfly_float_c;
  255.     c->downmix = ac3_downmix_c;
  256.  
  257.     if (ARCH_ARM)
  258.         ff_ac3dsp_init_arm(c, bit_exact);
  259.     if (ARCH_X86)
  260.         ff_ac3dsp_init_x86(c, bit_exact);
  261.     if (ARCH_MIPS)
  262.         ff_ac3dsp_init_mips(c, bit_exact);
  263. }
  264.