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>
7 * This file is part of FFmpeg.
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.
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.
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
26 * AC-3 encoder float/fixed template
31 #include "libavutil/attributes.h"
32 #include "libavutil/internal.h"
33 #include "libavutil/mem_internal.h"
41 static int allocate_sample_buffers(AC3EncodeContext *s)
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);
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);
60 * Channels are reordered from FFmpeg's default order to AC-3 order.
62 static void copy_input_samples(AC3EncodeContext *s, SampleType **samples)
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]));
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]));
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.
85 static void apply_mdct(AC3EncodeContext *s)
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];
94 s->fdsp->vector_fmul(s->windowed_samples, input_samples,
95 s->mdct_window, AC3_WINDOW_SIZE);
97 s->mdct.mdct_calc(&s->mdct, block->mdct_coef[ch+1],
105 * Calculate coupling channel and coupling coordinates.
107 static void apply_channel_coupling(AC3EncodeContext *s)
109 LOCAL_ALIGNED_16(CoefType, cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
111 LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
113 int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords;
115 int av_uninit(blk), ch, bnd, i, j;
116 CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
117 int cpl_start, num_cpl_coefs;
119 memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
121 memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
124 /* align start to 16-byte boundary. align length to multiple of 32.
125 note: coupling start bin % 4 will always be 1 */
126 cpl_start = s->start_freq[CPL_CH] - 1;
127 num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
128 cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
130 /* calculate coupling channel from fbw channels */
131 for (blk = 0; blk < s->num_blocks; blk++) {
132 AC3Block *block = &s->blocks[blk];
133 CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
134 if (!block->cpl_in_use)
136 memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
137 for (ch = 1; ch <= s->fbw_channels; ch++) {
138 CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
139 if (!block->channel_in_cpl[ch])
141 for (i = 0; i < num_cpl_coefs; i++)
142 cpl_coef[i] += ch_coef[i];
145 /* coefficients must be clipped in order to be encoded */
146 clip_coefficients(&s->adsp, cpl_coef, num_cpl_coefs);
149 /* calculate energy in each band in coupling channel and each fbw channel */
150 /* TODO: possibly use SIMD to speed up energy calculation */
152 i = s->start_freq[CPL_CH];
153 while (i < s->cpl_end_freq) {
154 int band_size = s->cpl_band_sizes[bnd];
155 for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
156 for (blk = 0; blk < s->num_blocks; blk++) {
157 AC3Block *block = &s->blocks[blk];
158 if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
160 for (j = 0; j < band_size; j++) {
161 CoefType v = block->mdct_coef[ch][i+j];
162 MAC_COEF(energy[blk][ch][bnd], v, v);
170 /* calculate coupling coordinates for all blocks for all channels */
171 for (blk = 0; blk < s->num_blocks; blk++) {
172 AC3Block *block = &s->blocks[blk];
173 if (!block->cpl_in_use)
175 for (ch = 1; ch <= s->fbw_channels; ch++) {
176 if (!block->channel_in_cpl[ch])
178 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
179 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
180 energy[blk][CPL_CH][bnd]);
185 /* determine which blocks to send new coupling coordinates for */
186 for (blk = 0; blk < s->num_blocks; blk++) {
187 AC3Block *block = &s->blocks[blk];
188 AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
190 memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords));
192 if (block->cpl_in_use) {
193 /* send new coordinates if this is the first block, if previous
194 * block did not use coupling but this block does, the channels
195 * using coupling has changed from the previous block, or the
196 * coordinate difference from the last block for any channel is
197 * greater than a threshold value. */
198 if (blk == 0 || !block0->cpl_in_use) {
199 for (ch = 1; ch <= s->fbw_channels; ch++)
200 block->new_cpl_coords[ch] = 1;
202 for (ch = 1; ch <= s->fbw_channels; ch++) {
203 if (!block->channel_in_cpl[ch])
205 if (!block0->channel_in_cpl[ch]) {
206 block->new_cpl_coords[ch] = 1;
208 CoefSumType coord_diff = 0;
209 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
210 coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] -
211 cpl_coords[blk ][ch][bnd]);
213 coord_diff /= s->num_cpl_bands;
214 if (coord_diff > NEW_CPL_COORD_THRESHOLD)
215 block->new_cpl_coords[ch] = 1;
222 /* calculate final coupling coordinates, taking into account reusing of
223 coordinates in successive blocks */
224 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
226 while (blk < s->num_blocks) {
228 AC3Block *block = &s->blocks[blk];
230 if (!block->cpl_in_use) {
235 for (ch = 1; ch <= s->fbw_channels; ch++) {
236 CoefSumType energy_ch, energy_cpl;
237 if (!block->channel_in_cpl[ch])
239 energy_cpl = energy[blk][CPL_CH][bnd];
240 energy_ch = energy[blk][ch][bnd];
242 while (blk1 < s->num_blocks && !s->blocks[blk1].new_cpl_coords[ch]) {
243 if (s->blocks[blk1].cpl_in_use) {
244 energy_cpl += energy[blk1][CPL_CH][bnd];
245 energy_ch += energy[blk1][ch][bnd];
249 cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
255 /* calculate exponents/mantissas for coupling coordinates */
256 for (blk = 0; blk < s->num_blocks; blk++) {
257 AC3Block *block = &s->blocks[blk];
258 if (!block->cpl_in_use)
262 s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
264 s->fbw_channels * 16);
266 s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
267 fixed_cpl_coords[blk][1],
268 s->fbw_channels * 16);
270 for (ch = 1; ch <= s->fbw_channels; ch++) {
271 int bnd, min_exp, max_exp, master_exp;
273 if (!block->new_cpl_coords[ch])
276 /* determine master exponent */
277 min_exp = max_exp = block->cpl_coord_exp[ch][0];
278 for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
279 int exp = block->cpl_coord_exp[ch][bnd];
280 min_exp = FFMIN(exp, min_exp);
281 max_exp = FFMAX(exp, max_exp);
283 master_exp = ((max_exp - 15) + 2) / 3;
284 master_exp = FFMAX(master_exp, 0);
285 while (min_exp < master_exp * 3)
287 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
288 block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
289 master_exp * 3, 0, 15);
291 block->cpl_master_exp[ch] = master_exp;
293 /* quantize mantissas */
294 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
295 int cpl_exp = block->cpl_coord_exp[ch][bnd];
296 int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
302 block->cpl_coord_mant[ch][bnd] = cpl_mant;
307 if (AC3ENC_FLOAT && CONFIG_EAC3_ENCODER && s->eac3)
308 ff_eac3_set_cpl_states(s);
313 * Determine rematrixing flags for each block and band.
315 static void compute_rematrixing_strategy(AC3EncodeContext *s)
319 AC3Block *block, *block0 = NULL;
321 if (s->channel_mode != AC3_CHMODE_STEREO)
324 for (blk = 0; blk < s->num_blocks; blk++) {
325 block = &s->blocks[blk];
326 block->new_rematrixing_strategy = !blk;
328 block->num_rematrixing_bands = 4;
329 if (block->cpl_in_use) {
330 block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
331 block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
332 if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
333 block->new_rematrixing_strategy = 1;
335 nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
337 if (!s->rematrixing_enabled) {
342 for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
343 /* calculate sum of squared coeffs for one band in one block */
344 int start = ff_ac3_rematrix_band_tab[bnd];
345 int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
347 sum_square_butterfly(s, sum, block->mdct_coef[1] + start,
348 block->mdct_coef[2] + start, end - start);
350 /* compare sums to determine if rematrixing will be used for this band */
351 if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
352 block->rematrixing_flags[bnd] = 1;
354 block->rematrixing_flags[bnd] = 0;
356 /* determine if new rematrixing flags will be sent */
358 block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
359 block->new_rematrixing_strategy = 1;
367 int AC3_NAME(encode_frame)(AVCodecContext *avctx, AVPacket *avpkt,
368 const AVFrame *frame, int *got_packet_ptr)
370 AC3EncodeContext *s = avctx->priv_data;
373 if (s->options.allow_per_frame_metadata) {
374 ret = ff_ac3_validate_metadata(s);
379 if (s->bit_alloc.sr_code == 1 || (AC3ENC_FLOAT && s->eac3))
380 ff_ac3_adjust_frame_size(s);
382 copy_input_samples(s, (SampleType **)frame->extended_data);
386 clip_coefficients(&s->adsp, s->blocks[0].mdct_coef[1],
387 AC3_MAX_COEFS * s->num_blocks * s->channels);
389 s->cpl_on = s->cpl_enabled;
390 ff_ac3_compute_coupling_strategy(s);
393 apply_channel_coupling(s);
395 compute_rematrixing_strategy(s);
398 scale_coefficients(s);
401 return ff_ac3_encode_frame_common_end(avctx, avpkt, frame, got_packet_ptr);