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
allocate_sample_buffers(AC3EncodeContext * s)41 static int allocate_sample_buffers(AC3EncodeContext *s)
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 */
copy_input_samples(AC3EncodeContext * s,SampleType ** samples)62 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
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 */
apply_mdct(AC3EncodeContext * s)85 static void apply_mdct(AC3EncodeContext *s)
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 */
apply_channel_coupling(AC3EncodeContext * s)110 static void apply_channel_coupling(AC3EncodeContext *s)
111 {
112 LOCAL_ALIGNED_16(CoefType, cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
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)
311 ff_eac3_set_cpl_states(s);
312 }
313
314
315 /*
316 * Determine rematrixing flags for each block and band.
317 */
compute_rematrixing_strategy(AC3EncodeContext * s)318 static void compute_rematrixing_strategy(AC3EncodeContext *s)
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
AC3_NAME(encode_frame)370 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
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) {
377 ret = ff_ac3_validate_metadata(s);
378 if (ret)
379 return ret;
380 }
381
382 if (s->bit_alloc.sr_code == 1 || (AC3ENC_FLOAT && s->eac3))
383 ff_ac3_adjust_frame_size(s);
384
385 copy_input_samples(s, (SampleType **)frame->extended_data);
386
387 apply_mdct(s);
388
389 s->cpl_on = s->cpl_enabled;
390 ff_ac3_compute_coupling_strategy(s);
391
392 if (s->cpl_on)
393 apply_channel_coupling(s);
394
395 compute_rematrixing_strategy(s);
396
397 #if AC3ENC_FLOAT
398 scale_coefficients(s);
399 #endif
400
401 return ff_ac3_encode_frame_common_end(avctx, avpkt, frame, got_packet_ptr);
402 }
403