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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
34 #include "audiodsp.h"
35 #include "internal.h"
36 #include "ac3enc.h"
37 #include "eac3enc.h"
38
39
40 int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
41 {
42     int ch;
43
44     FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
45                      sizeof(*s->windowed_samples), alloc_fail);
46     FF_ALLOC_ARRAY_OR_GOTO(s->avctx, s->planar_samples, s->channels, sizeof(*s->planar_samples),
47                      alloc_fail);
48     for (ch = 0; ch < s->channels; ch++) {
49         FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
50                           (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
51                           alloc_fail);
52     }
53
54     return 0;
55 alloc_fail:
56     return AVERROR(ENOMEM);
57 }
58
59
60 /*
61  * Copy input samples.
62  * Channels are reordered from FFmpeg's default order to AC-3 order.
63  */
64 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
65 {
66     int ch;
67
68     /* copy and remap input samples */
69     for (ch = 0; ch < s->channels; ch++) {
70         /* copy last 256 samples of previous frame to the start of the current frame */
71         memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks],
72                AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
73
74         /* copy new samples for current frame */
75         memcpy(&s->planar_samples[ch][AC3_BLOCK_SIZE],
76                samples[s->channel_map[ch]],
77                AC3_BLOCK_SIZE * s->num_blocks * sizeof(s->planar_samples[0][0]));
78     }
79 }
80
81
82 /*
83  * Apply the MDCT to input samples to generate frequency coefficients.
84  * This applies the KBD window and normalizes the input to reduce precision
85  * loss due to fixed-point calculations.
86  */
87 static void apply_mdct(AC3EncodeContext *s)
88 {
89     int blk, ch;
90
91     for (ch = 0; ch < s->channels; ch++) {
92         for (blk = 0; blk < s->num_blocks; blk++) {
93             AC3Block *block = &s->blocks[blk];
94             const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
95
96 #if CONFIG_AC3ENC_FLOAT
97             s->fdsp->vector_fmul(s->windowed_samples, input_samples,
98                                 s->mdct_window, AC3_WINDOW_SIZE);
99 #else
100             s->ac3dsp.apply_window_int16(s->windowed_samples, input_samples,
101                                          s->mdct_window, AC3_WINDOW_SIZE);
102
103             if (s->fixed_point)
104                 block->coeff_shift[ch+1] = normalize_samples(s);
105 #endif
106
107             s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1],
108                                s->windowed_samples);
109         }
110     }
111 }
112
113
114 /*
115  * Calculate coupling channel and coupling coordinates.
116  */
117 static void apply_channel_coupling(AC3EncodeContext *s)
118 {
119     LOCAL_ALIGNED_16(CoefType, cpl_coords,      [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
120 #if CONFIG_AC3ENC_FLOAT
121     LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
122 #else
123     int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
124 #endif
125     int av_uninit(blk), ch, bnd, i, j;
126     CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
127     int cpl_start, num_cpl_coefs;
128
129     memset(cpl_coords,       0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
130 #if CONFIG_AC3ENC_FLOAT
131     memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
132 #endif
133
134     /* align start to 16-byte boundary. align length to multiple of 32.
135         note: coupling start bin % 4 will always be 1 */
136     cpl_start     = s->start_freq[CPL_CH] - 1;
137     num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
138     cpl_start     = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
139
140     /* calculate coupling channel from fbw channels */
141     for (blk = 0; blk < s->num_blocks; blk++) {
142         AC3Block *block = &s->blocks[blk];
143         CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
144         if (!block->cpl_in_use)
145             continue;
146         memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
147         for (ch = 1; ch <= s->fbw_channels; ch++) {
148             CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
149             if (!block->channel_in_cpl[ch])
150                 continue;
151             for (i = 0; i < num_cpl_coefs; i++)
152                 cpl_coef[i] += ch_coef[i];
153         }
154
155         /* coefficients must be clipped in order to be encoded */
156         clip_coefficients(&s->adsp, cpl_coef, num_cpl_coefs);
157     }
158
159     /* calculate energy in each band in coupling channel and each fbw channel */
160     /* TODO: possibly use SIMD to speed up energy calculation */
161     bnd = 0;
162     i = s->start_freq[CPL_CH];
163     while (i < s->cpl_end_freq) {
164         int band_size = s->cpl_band_sizes[bnd];
165         for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
166             for (blk = 0; blk < s->num_blocks; blk++) {
167                 AC3Block *block = &s->blocks[blk];
168                 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
169                     continue;
170                 for (j = 0; j < band_size; j++) {
171                     CoefType v = block->mdct_coef[ch][i+j];
172                     MAC_COEF(energy[blk][ch][bnd], v, v);
173                 }
174             }
175         }
176         i += band_size;
177         bnd++;
178     }
179
180     /* calculate coupling coordinates for all blocks for all channels */
181     for (blk = 0; blk < s->num_blocks; blk++) {
182         AC3Block *block  = &s->blocks[blk];
183         if (!block->cpl_in_use)
184             continue;
185         for (ch = 1; ch <= s->fbw_channels; ch++) {
186             if (!block->channel_in_cpl[ch])
187                 continue;
188             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
189                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
190                                                           energy[blk][CPL_CH][bnd]);
191             }
192         }
193     }
194
195     /* determine which blocks to send new coupling coordinates for */
196     for (blk = 0; blk < s->num_blocks; blk++) {
197         AC3Block *block  = &s->blocks[blk];
198         AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
199
200         memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
201
202         if (block->cpl_in_use) {
203             /* send new coordinates if this is the first block, if previous
204              * block did not use coupling but this block does, the channels
205              * using coupling has changed from the previous block, or the
206              * coordinate difference from the last block for any channel is
207              * greater than a threshold value. */
208             if (blk == 0 || !block0->cpl_in_use) {
209                 for (ch = 1; ch <= s->fbw_channels; ch++)
210                     block->new_cpl_coords[ch] = 1;
211             } else {
212                 for (ch = 1; ch <= s->fbw_channels; ch++) {
213                     if (!block->channel_in_cpl[ch])
214                         continue;
215                     if (!block0->channel_in_cpl[ch]) {
216                         block->new_cpl_coords[ch] = 1;
217                     } else {
218                         CoefSumType coord_diff = 0;
219                         for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
220                             coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
221                                                 cpl_coords[blk  ][ch][bnd]);
222                         }
223                         coord_diff /= s->num_cpl_bands;
224                         if (coord_diff > NEW_CPL_COORD_THRESHOLD)
225                             block->new_cpl_coords[ch] = 1;
226                     }
227                 }
228             }
229         }
230     }
231
232     /* calculate final coupling coordinates, taking into account reusing of
233        coordinates in successive blocks */
234     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
235         blk = 0;
236         while (blk < s->num_blocks) {
237             int av_uninit(blk1);
238             AC3Block *block  = &s->blocks[blk];
239
240             if (!block->cpl_in_use) {
241                 blk++;
242                 continue;
243             }
244
245             for (ch = 1; ch <= s->fbw_channels; ch++) {
246                 CoefSumType energy_ch, energy_cpl;
247                 if (!block->channel_in_cpl[ch])
248                     continue;
249                 energy_cpl = energy[blk][CPL_CH][bnd];
250                 energy_ch = energy[blk][ch][bnd];
251                 blk1 = blk+1;
252                 while (blk1 < s->num_blocks && !s->blocks[blk1].new_cpl_coords[ch]) {
253                     if (s->blocks[blk1].cpl_in_use) {
254                         energy_cpl += energy[blk1][CPL_CH][bnd];
255                         energy_ch += energy[blk1][ch][bnd];
256                     }
257                     blk1++;
258                 }
259                 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
260             }
261             blk = blk1;
262         }
263     }
264
265     /* calculate exponents/mantissas for coupling coordinates */
266     for (blk = 0; blk < s->num_blocks; blk++) {
267         AC3Block *block = &s->blocks[blk];
268         if (!block->cpl_in_use)
269             continue;
270
271 #if CONFIG_AC3ENC_FLOAT
272         s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
273                                    cpl_coords[blk][1],
274                                    s->fbw_channels * 16);
275 #endif
276         s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
277                                     fixed_cpl_coords[blk][1],
278                                     s->fbw_channels * 16);
279
280         for (ch = 1; ch <= s->fbw_channels; ch++) {
281             int bnd, min_exp, max_exp, master_exp;
282
283             if (!block->new_cpl_coords[ch])
284                 continue;
285
286             /* determine master exponent */
287             min_exp = max_exp = block->cpl_coord_exp[ch][0];
288             for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
289                 int exp = block->cpl_coord_exp[ch][bnd];
290                 min_exp = FFMIN(exp, min_exp);
291                 max_exp = FFMAX(exp, max_exp);
292             }
293             master_exp = ((max_exp - 15) + 2) / 3;
294             master_exp = FFMAX(master_exp, 0);
295             while (min_exp < master_exp * 3)
296                 master_exp--;
297             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
298                 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
299                                                         master_exp * 3, 0, 15);
300             }
301             block->cpl_master_exp[ch] = master_exp;
302
303             /* quantize mantissas */
304             for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
305                 int cpl_exp  = block->cpl_coord_exp[ch][bnd];
306                 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
307                 if (cpl_exp == 15)
308                     cpl_mant >>= 1;
309                 else
310                     cpl_mant -= 16;
311
312                 block->cpl_coord_mant[ch][bnd] = cpl_mant;
313             }
314         }
315     }
316
317     if (CONFIG_EAC3_ENCODER && s->eac3)
318         ff_eac3_set_cpl_states(s);
319 }
320
321
322 /*
323  * Determine rematrixing flags for each block and band.
324  */
325 static void compute_rematrixing_strategy(AC3EncodeContext *s)
326 {
327     int nb_coefs;
328     int blk, bnd;
329     AC3Block *block, *block0 = NULL;
330
331     if (s->channel_mode != AC3_CHMODE_STEREO)
332         return;
333
334     for (blk = 0; blk < s->num_blocks; blk++) {
335         block = &s->blocks[blk];
336         block->new_rematrixing_strategy = !blk;
337
338         block->num_rematrixing_bands = 4;
339         if (block->cpl_in_use) {
340             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
341             block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
342             if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
343                 block->new_rematrixing_strategy = 1;
344         }
345         nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
346
347         if (!s->rematrixing_enabled) {
348             block0 = block;
349             continue;
350         }
351
352         for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
353             /* calculate sum of squared coeffs for one band in one block */
354             int start = ff_ac3_rematrix_band_tab[bnd];
355             int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
356             CoefSumType sum[4];
357             sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
358                                  block->mdct_coef[2] + start, end - start);
359
360             /* compare sums to determine if rematrixing will be used for this band */
361             if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
362                 block->rematrixing_flags[bnd] = 1;
363             else
364                 block->rematrixing_flags[bnd] = 0;
365
366             /* determine if new rematrixing flags will be sent */
367             if (blk &&
368                 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
369                 block->new_rematrixing_strategy = 1;
370             }
371         }
372         block0 = block;
373     }
374 }
375
376
377 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
378                            const AVFrame *frame, int *got_packet_ptr)
379 {
380     AC3EncodeContext *s = avctx->priv_data;
381     int ret;
382
383     if (s->options.allow_per_frame_metadata) {
384         ret = ff_ac3_validate_metadata(s);
385         if (ret)
386             return ret;
387     }
388
389     if (s->bit_alloc.sr_code == 1 || s->eac3)
390         ff_ac3_adjust_frame_size(s);
391
392     copy_input_samples(s, (SampleType **)frame->extended_data);
393
394     apply_mdct(s);
395
396     if (s->fixed_point)
397         scale_coefficients(s);
398
399     clip_coefficients(&s->adsp, s->blocks[0].mdct_coef[1],
400                       AC3_MAX_COEFS * s->num_blocks * s->channels);
401
402     s->cpl_on = s->cpl_enabled;
403     ff_ac3_compute_coupling_strategy(s);
404
405     if (s->cpl_on)
406         apply_channel_coupling(s);
407
408     compute_rematrixing_strategy(s);
409
410     if (!s->fixed_point)
411         scale_coefficients(s);
412
413     ff_ac3_apply_rematrixing(s);
414
415     ff_ac3_process_exponents(s);
416
417     ret = ff_ac3_compute_bit_allocation(s);
418     if (ret) {
419         av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
420         return ret;
421     }
422
423     ff_ac3_group_exponents(s);
424
425     ff_ac3_quantize_mantissas(s);
426
427     if ((ret = ff_alloc_packet2(avctx, avpkt, s->frame_size, 0)) < 0)
428         return ret;
429     ff_ac3_output_frame(s, avpkt->data);
430
431     if (frame->pts != AV_NOPTS_VALUE)
432         avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->initial_padding);
433
434     *got_packet_ptr = 1;
435     return 0;
436 }