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ac3dsp.c
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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 {
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 }