FFmpeg  4.4
ac3enc_template.c
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1 /*
2  * AC-3 encoder float/fixed template
3  * Copyright (c) 2000 Fabrice Bellard
4  * Copyright (c) 2006-2011 Justin Ruggles <justin.ruggles@gmail.com>
5  * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 /**
25  * @file
26  * AC-3 encoder float/fixed template
27  */
28 
29 #include <stdint.h>
30 
31 #include "libavutil/attributes.h"
32 #include "libavutil/internal.h"
33 #include "libavutil/mem_internal.h"
34 
35 #include "audiodsp.h"
36 #include "internal.h"
37 #include "ac3enc.h"
38 #include "eac3enc.h"
39 
40 
42 {
43  int ch;
44 
45  if (!FF_ALLOC_TYPED_ARRAY(s->windowed_samples, AC3_WINDOW_SIZE) ||
46  !FF_ALLOCZ_TYPED_ARRAY(s->planar_samples, s->channels))
47  return AVERROR(ENOMEM);
48 
49  for (ch = 0; ch < s->channels; ch++) {
50  if (!(s->planar_samples[ch] = av_mallocz((AC3_FRAME_SIZE + AC3_BLOCK_SIZE) *
51  sizeof(**s->planar_samples))))
52  return AVERROR(ENOMEM);
53  }
54  return 0;
55 }
56 
57 
58 /*
59  * Copy input samples.
60  * Channels are reordered from FFmpeg's default order to AC-3 order.
61  */
63 {
64  int ch;
65 
66  /* copy and remap input samples */
67  for (ch = 0; ch < s->channels; ch++) {
68  /* copy last 256 samples of previous frame to the start of the current frame */
69  memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
70  AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
71 
72  /* copy new samples for current frame */
73  memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
74  samples[s->channel_map[ch]],
75  AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
76  }
77 }
78 
79 
80 /*
81  * Apply the MDCT to input samples to generate frequency coefficients.
82  * This applies the KBD window and normalizes the input to reduce precision
83  * loss due to fixed-point calculations.
84  */
86 {
87  int blk, ch;
88 
89  for (ch = 0; ch < s->channels; ch++) {
90  for (blk = 0; blk < s->num_blocks; blk++) {
91  AC3Block *block = &s->blocks[blk];
92  const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
93 
94  s->fdsp->vector_fmul(s->windowed_samples, input_samples,
95  s->mdct_window, AC3_BLOCK_SIZE);
96  s->fdsp->vector_fmul_reverse(s->windowed_samples + AC3_BLOCK_SIZE,
97  &input_samples[AC3_BLOCK_SIZE],
98  s->mdct_window, AC3_BLOCK_SIZE);
99 
100  s->mdct.mdct_calc(&s->mdct, block->mdct_coef[ch+1],
101  s->windowed_samples);
102  }
103  }
104 }
105 
106 
107 /*
108  * Calculate coupling channel and coupling coordinates.
109  */
111 {
113 #if AC3ENC_FLOAT
114  LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
115 #else
116  int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
117 #endif
118  int av_uninit(blk), ch, bnd, i, j;
119  CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
120  int cpl_start, num_cpl_coefs;
121 
122  memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
123 #if AC3ENC_FLOAT
124  memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
125 #endif
126 
127  /* align start to 16-byte boundary. align length to multiple of 32.
128  note: coupling start bin % 4 will always be 1 */
129  cpl_start = s->start_freq[CPL_CH] - 1;
130  num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
131  cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
132 
133  /* calculate coupling channel from fbw channels */
134  for (blk = 0; blk < s->num_blocks; blk++) {
135  AC3Block *block = &s->blocks[blk];
136  CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
137  if (!block->cpl_in_use)
138  continue;
139  memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
140  for (ch = 1; ch <= s->fbw_channels; ch++) {
141  CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
142  if (!block->channel_in_cpl[ch])
143  continue;
144  for (i = 0; i < num_cpl_coefs; i++)
145  cpl_coef[i] += ch_coef[i];
146  }
147 
148  /* coefficients must be clipped in order to be encoded */
149  clip_coefficients(&s->adsp, cpl_coef, num_cpl_coefs);
150  }
151 
152  /* calculate energy in each band in coupling channel and each fbw channel */
153  /* TODO: possibly use SIMD to speed up energy calculation */
154  bnd = 0;
155  i = s->start_freq[CPL_CH];
156  while (i < s->cpl_end_freq) {
157  int band_size = s->cpl_band_sizes[bnd];
158  for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
159  for (blk = 0; blk < s->num_blocks; blk++) {
160  AC3Block *block = &s->blocks[blk];
161  if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
162  continue;
163  for (j = 0; j < band_size; j++) {
164  CoefType v = block->mdct_coef[ch][i+j];
165  MAC_COEF(energy[blk][ch][bnd], v, v);
166  }
167  }
168  }
169  i += band_size;
170  bnd++;
171  }
172 
173  /* calculate coupling coordinates for all blocks for all channels */
174  for (blk = 0; blk < s->num_blocks; blk++) {
175  AC3Block *block = &s->blocks[blk];
176  if (!block->cpl_in_use)
177  continue;
178  for (ch = 1; ch <= s->fbw_channels; ch++) {
179  if (!block->channel_in_cpl[ch])
180  continue;
181  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
182  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
183  energy[blk][CPL_CH][bnd]);
184  }
185  }
186  }
187 
188  /* determine which blocks to send new coupling coordinates for */
189  for (blk = 0; blk < s->num_blocks; blk++) {
190  AC3Block *block = &s->blocks[blk];
191  AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
192 
193  memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
194 
195  if (block->cpl_in_use) {
196  /* send new coordinates if this is the first block, if previous
197  * block did not use coupling but this block does, the channels
198  * using coupling has changed from the previous block, or the
199  * coordinate difference from the last block for any channel is
200  * greater than a threshold value. */
201  if (blk == 0 || !block0->cpl_in_use) {
202  for (ch = 1; ch <= s->fbw_channels; ch++)
203  block->new_cpl_coords[ch] = 1;
204  } else {
205  for (ch = 1; ch <= s->fbw_channels; ch++) {
206  if (!block->channel_in_cpl[ch])
207  continue;
208  if (!block0->channel_in_cpl[ch]) {
209  block->new_cpl_coords[ch] = 1;
210  } else {
211  CoefSumType coord_diff = 0;
212  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
213  coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
214  cpl_coords[blk ][ch][bnd]);
215  }
216  coord_diff /= s->num_cpl_bands;
217  if (coord_diff > NEW_CPL_COORD_THRESHOLD)
218  block->new_cpl_coords[ch] = 1;
219  }
220  }
221  }
222  }
223  }
224 
225  /* calculate final coupling coordinates, taking into account reusing of
226  coordinates in successive blocks */
227  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
228  blk = 0;
229  while (blk < s->num_blocks) {
230  int av_uninit(blk1);
231  AC3Block *block = &s->blocks[blk];
232 
233  if (!block->cpl_in_use) {
234  blk++;
235  continue;
236  }
237 
238  for (ch = 1; ch <= s->fbw_channels; ch++) {
239  CoefSumType energy_ch, energy_cpl;
240  if (!block->channel_in_cpl[ch])
241  continue;
242  energy_cpl = energy[blk][CPL_CH][bnd];
243  energy_ch = energy[blk][ch][bnd];
244  blk1 = blk+1;
245  while (blk1 < s->num_blocks && !s->blocks[blk1].new_cpl_coords[ch]) {
246  if (s->blocks[blk1].cpl_in_use) {
247  energy_cpl += energy[blk1][CPL_CH][bnd];
248  energy_ch += energy[blk1][ch][bnd];
249  }
250  blk1++;
251  }
252  cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
253  }
254  blk = blk1;
255  }
256  }
257 
258  /* calculate exponents/mantissas for coupling coordinates */
259  for (blk = 0; blk < s->num_blocks; blk++) {
260  AC3Block *block = &s->blocks[blk];
261  if (!block->cpl_in_use)
262  continue;
263 
264 #if AC3ENC_FLOAT
265  s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
266  cpl_coords[blk][1],
267  s->fbw_channels * 16);
268 #endif
269  s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
270  fixed_cpl_coords[blk][1],
271  s->fbw_channels * 16);
272 
273  for (ch = 1; ch <= s->fbw_channels; ch++) {
274  int bnd, min_exp, max_exp, master_exp;
275 
276  if (!block->new_cpl_coords[ch])
277  continue;
278 
279  /* determine master exponent */
280  min_exp = max_exp = block->cpl_coord_exp[ch][0];
281  for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
282  int exp = block->cpl_coord_exp[ch][bnd];
283  min_exp = FFMIN(exp, min_exp);
284  max_exp = FFMAX(exp, max_exp);
285  }
286  master_exp = ((max_exp - 15) + 2) / 3;
287  master_exp = FFMAX(master_exp, 0);
288  while (min_exp < master_exp * 3)
289  master_exp--;
290  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
291  block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
292  master_exp * 3, 0, 15);
293  }
294  block->cpl_master_exp[ch] = master_exp;
295 
296  /* quantize mantissas */
297  for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
298  int cpl_exp = block->cpl_coord_exp[ch][bnd];
299  int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
300  if (cpl_exp == 15)
301  cpl_mant >>= 1;
302  else
303  cpl_mant -= 16;
304 
305  block->cpl_coord_mant[ch][bnd] = cpl_mant;
306  }
307  }
308  }
309 
310  if (AC3ENC_FLOAT && CONFIG_EAC3_ENCODER && s->eac3)
312 }
313 
314 
315 /*
316  * Determine rematrixing flags for each block and band.
317  */
319 {
320  int nb_coefs;
321  int blk, bnd;
322  AC3Block *block, *block0 = NULL;
323 
324  if (s->channel_mode != AC3_CHMODE_STEREO)
325  return;
326 
327  for (blk = 0; blk < s->num_blocks; blk++) {
328  block = &s->blocks[blk];
329  block->new_rematrixing_strategy = !blk;
330 
331  block->num_rematrixing_bands = 4;
332  if (block->cpl_in_use) {
333  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
334  block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
335  if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
336  block->new_rematrixing_strategy = 1;
337  }
338  nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
339 
340  if (!s->rematrixing_enabled) {
341  block0 = block;
342  continue;
343  }
344 
345  for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
346  /* calculate sum of squared coeffs for one band in one block */
347  int start = ff_ac3_rematrix_band_tab[bnd];
348  int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
349  CoefSumType sum[4];
350  sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
351  block->mdct_coef[2] + start, end - start);
352 
353  /* compare sums to determine if rematrixing will be used for this band */
354  if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
355  block->rematrixing_flags[bnd] = 1;
356  else
357  block->rematrixing_flags[bnd] = 0;
358 
359  /* determine if new rematrixing flags will be sent */
360  if (blk &&
361  block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
362  block->new_rematrixing_strategy = 1;
363  }
364  }
365  block0 = block;
366  }
367 }
368 
369 
371  const AVFrame *frame, int *got_packet_ptr)
372 {
373  AC3EncodeContext *s = avctx->priv_data;
374  int ret;
375 
376  if (s->options.allow_per_frame_metadata) {
378  if (ret)
379  return ret;
380  }
381 
382  if (s->bit_alloc.sr_code == 1 || (AC3ENC_FLOAT && s->eac3))
384 
386 
387  apply_mdct(s);
388 
389  s->cpl_on = s->cpl_enabled;
391 
392  if (s->cpl_on)
394 
396 
397 #if AC3ENC_FLOAT
399 #endif
400 
401  return ff_ac3_encode_frame_common_end(avctx, avpkt, frame, got_packet_ptr);
402 }
#define CPL_CH
coupling channel index
Definition: ac3.h:32
#define AC3_MAX_CHANNELS
maximum number of channels, including coupling channel
Definition: ac3.h:31
#define AC3_BLOCK_SIZE
Definition: ac3.h:35
#define AC3_WINDOW_SIZE
Definition: ac3.h:38
@ AC3_CHMODE_STEREO
Definition: ac3.h:125
#define AC3_FRAME_SIZE
Definition: ac3.h:37
#define AC3_MAX_BLOCKS
Definition: ac3.h:36
int ff_ac3_validate_metadata(AC3EncodeContext *s)
Validate metadata options as set by AVOption system.
Definition: ac3enc.c:1930
void ff_ac3_adjust_frame_size(AC3EncodeContext *s)
Adjust the frame size to make the average bit rate match the target bit rate.
Definition: ac3enc.c:253
void ff_ac3_compute_coupling_strategy(AC3EncodeContext *s)
Set the initial coupling strategy parameters prior to coupling analysis.
Definition: ac3enc.c:271
int ff_ac3_encode_frame_common_end(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame, int *got_packet_ptr)
Definition: ac3enc.c:1742
AC-3 encoder & E-AC-3 encoder common header.
#define NEW_CPL_COORD_THRESHOLD
Definition: ac3enc.h:62
#define MAC_COEF(d, a, b)
Definition: ac3enc.h:59
int32_t SampleType
Definition: ac3enc.h:63
#define AC3ENC_FLOAT
Definition: ac3enc.h:43
int64_t CoefSumType
Definition: ac3enc.h:65
#define AC3_NAME(x)
Definition: ac3enc.h:58
int32_t CoefType
Definition: ac3enc.h:64
static void clip_coefficients(AudioDSPContext *adsp, int32_t *coef, unsigned int len)
Definition: ac3enc_fixed.c:55
static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4], const int32_t *coef0, const int32_t *coef1, int len)
Definition: ac3enc_fixed.c:45
static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
Definition: ac3enc_fixed.c:65
static void scale_coefficients(AC3EncodeContext *s)
Definition: ac3enc_float.c:48
static void apply_channel_coupling(AC3EncodeContext *s)
static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
static int allocate_sample_buffers(AC3EncodeContext *s)
static void compute_rematrixing_strategy(AC3EncodeContext *s)
static void apply_mdct(AC3EncodeContext *s)
int AC3_NAME() encode_frame(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame, int *got_packet_ptr)
const uint8_t ff_ac3_rematrix_band_tab[5]
Table of bin locations for rematrixing bands reference: Section 7.5.2 Rematrixing : Frequency Band De...
Definition: ac3tab.c:123
Macro definitions for various function/variable attributes.
#define av_uninit(x)
Definition: attributes.h:154
int32_t
#define s(width, name)
Definition: cbs_vp9.c:257
#define FFMIN(a, b)
Definition: common.h:105
#define av_clip
Definition: common.h:122
#define FFMAX(a, b)
Definition: common.h:103
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:72
#define CONFIG_EAC3_ENCODER
Definition: config.h:1385
#define NULL
Definition: coverity.c:32
static AVFrame * frame
void ff_eac3_set_cpl_states(AC3EncodeContext *s)
Set coupling states.
Definition: eac3enc.c:92
E-AC-3 encoder.
int8_t exp
Definition: eval.c:72
#define AVERROR(e)
Definition: error.h:43
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:237
int i
Definition: input.c:407
common internal API header
#define FF_ALLOC_TYPED_ARRAY(p, nelem)
Definition: internal.h:102
#define FF_ALLOCZ_TYPED_ARRAY(p, nelem)
Definition: internal.h:103
#define FFALIGN(x, a)
Definition: macros.h:48
#define LOCAL_ALIGNED_16(t, v,...)
Definition: mem_internal.h:130
#define blk(i)
Definition: sha.c:185
Data for a single audio block.
Definition: ac3enc.h:126
uint8_t rematrixing_flags[4]
rematrixing flags
Definition: ac3enc.h:139
int num_rematrixing_bands
number of rematrixing bands
Definition: ac3enc.h:138
uint8_t channel_in_cpl[AC3_MAX_CHANNELS]
channel in coupling (chincpl)
Definition: ac3enc.h:142
int cpl_in_use
coupling in use for this block (cplinu)
Definition: ac3enc.h:141
AC-3 encoder private context.
Definition: ac3enc.h:154
main external API structure.
Definition: avcodec.h:536
This structure describes decoded (raw) audio or video data.
Definition: frame.h:318
uint8_t ** extended_data
pointers to the data planes/channels.
Definition: frame.h:365
This structure stores compressed data.
Definition: packet.h:346
static int16_t block[64]
Definition: dct.c:116