* Common code between the AC-3 encoder and decoder
* Copyright (c) 2000 Fabrice Bellard
*
- * This file is part of FFmpeg.
+ * This file is part of Libav.
*
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
- * @file libavcodec/ac3.c
+ * @file
* Common code between the AC-3 encoder and decoder.
*/
+#include "libavutil/common.h"
+
#include "avcodec.h"
#include "ac3.h"
-#include "get_bits.h"
-
-#if CONFIG_HARDCODED_TABLES
/**
* Starting frequency coefficient bin for each critical band.
*/
-static const uint8_t band_start_tab[51] = {
+const uint8_t ff_ac3_band_start_tab[AC3_CRITICAL_BANDS+1] = {
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 26, 27, 28, 31,
79, 85, 97, 109, 121, 133, 157, 181, 205, 229, 253
};
+#if CONFIG_HARDCODED_TABLES
+
/**
- * Maps each frequency coefficient bin to the critical band that contains it.
+ * Map each frequency coefficient bin to the critical band that contains it.
*/
-static const uint8_t bin_to_band_tab[253] = {
+const uint8_t ff_ac3_bin_to_band_tab[253] = {
0,
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
};
#else /* CONFIG_HARDCODED_TABLES */
-static uint8_t band_start_tab[51];
-static uint8_t bin_to_band_tab[253];
+uint8_t ff_ac3_bin_to_band_tab[253];
#endif
static inline int calc_lowcomp1(int a, int b0, int b1, int c)
void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
int16_t *band_psd)
{
- int bin, j, k;
+ int bin, band;
/* exponent mapping to PSD */
- for(bin=start;bin<end;bin++) {
+ for (bin = start; bin < end; bin++) {
psd[bin]=(3072 - (exp[bin] << 7));
}
/* PSD integration */
- j=start;
- k=bin_to_band_tab[start];
+ bin = start;
+ band = ff_ac3_bin_to_band_tab[start];
do {
- int v = psd[j++];
- int end1 = FFMIN(band_start_tab[k+1], end);
- for (; j < end1; j++) {
+ int v = psd[bin++];
+ int band_end = FFMIN(ff_ac3_band_start_tab[band+1], end);
+ for (; bin < band_end; bin++) {
+ int max = FFMAX(v, psd[bin]);
/* logadd */
- int adr = FFMIN(FFABS(v - psd[j]) >> 1, 255);
- v = FFMAX(v, psd[j]) + ff_ac3_log_add_tab[adr];
+ int adr = FFMIN(max - ((v + psd[bin] + 1) >> 1), 255);
+ v = max + ff_ac3_log_add_tab[adr];
}
- band_psd[k]=v;
- k++;
- } while (end > band_start_tab[k]);
+ band_psd[band++] = v;
+ } while (end > ff_ac3_band_start_tab[band]);
}
int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
uint8_t *dba_lengths, uint8_t *dba_values,
int16_t *mask)
{
- int16_t excite[50]; /* excitation */
- int bin, k;
- int bndstrt, bndend, begin, end1, tmp;
+ int16_t excite[AC3_CRITICAL_BANDS]; /* excitation */
+ int band;
+ int band_start, band_end, begin, end1;
int lowcomp, fastleak, slowleak;
/* excitation function */
- bndstrt = bin_to_band_tab[start];
- bndend = bin_to_band_tab[end-1] + 1;
+ band_start = ff_ac3_bin_to_band_tab[start];
+ band_end = ff_ac3_bin_to_band_tab[end-1] + 1;
- if (bndstrt == 0) {
+ if (band_start == 0) {
lowcomp = 0;
lowcomp = calc_lowcomp1(lowcomp, band_psd[0], band_psd[1], 384);
excite[0] = band_psd[0] - fast_gain - lowcomp;
lowcomp = calc_lowcomp1(lowcomp, band_psd[1], band_psd[2], 384);
excite[1] = band_psd[1] - fast_gain - lowcomp;
begin = 7;
- for (bin = 2; bin < 7; bin++) {
- if (!(is_lfe && bin == 6))
- lowcomp = calc_lowcomp1(lowcomp, band_psd[bin], band_psd[bin+1], 384);
- fastleak = band_psd[bin] - fast_gain;
- slowleak = band_psd[bin] - s->slow_gain;
- excite[bin] = fastleak - lowcomp;
- if (!(is_lfe && bin == 6)) {
- if (band_psd[bin] <= band_psd[bin+1]) {
- begin = bin + 1;
+ for (band = 2; band < 7; band++) {
+ if (!(is_lfe && band == 6))
+ lowcomp = calc_lowcomp1(lowcomp, band_psd[band], band_psd[band+1], 384);
+ fastleak = band_psd[band] - fast_gain;
+ slowleak = band_psd[band] - s->slow_gain;
+ excite[band] = fastleak - lowcomp;
+ if (!(is_lfe && band == 6)) {
+ if (band_psd[band] <= band_psd[band+1]) {
+ begin = band + 1;
break;
}
}
}
- end1=bndend;
- if (end1 > 22) end1=22;
-
- for (bin = begin; bin < end1; bin++) {
- if (!(is_lfe && bin == 6))
- lowcomp = calc_lowcomp(lowcomp, band_psd[bin], band_psd[bin+1], bin);
-
- fastleak = FFMAX(fastleak - s->fast_decay, band_psd[bin] - fast_gain);
- slowleak = FFMAX(slowleak - s->slow_decay, band_psd[bin] - s->slow_gain);
- excite[bin] = FFMAX(fastleak - lowcomp, slowleak);
+ end1 = FFMIN(band_end, 22);
+ for (band = begin; band < end1; band++) {
+ if (!(is_lfe && band == 6))
+ lowcomp = calc_lowcomp(lowcomp, band_psd[band], band_psd[band+1], band);
+ fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain);
+ slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain);
+ excite[band] = FFMAX(fastleak - lowcomp, slowleak);
}
begin = 22;
} else {
/* coupling channel */
- begin = bndstrt;
-
+ begin = band_start;
fastleak = (s->cpl_fast_leak << 8) + 768;
slowleak = (s->cpl_slow_leak << 8) + 768;
}
- for (bin = begin; bin < bndend; bin++) {
- fastleak = FFMAX(fastleak - s->fast_decay, band_psd[bin] - fast_gain);
- slowleak = FFMAX(slowleak - s->slow_decay, band_psd[bin] - s->slow_gain);
- excite[bin] = FFMAX(fastleak, slowleak);
+ for (band = begin; band < band_end; band++) {
+ fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain);
+ slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain);
+ excite[band] = FFMAX(fastleak, slowleak);
}
/* compute masking curve */
- for (bin = bndstrt; bin < bndend; bin++) {
- tmp = s->db_per_bit - band_psd[bin];
+ for (band = band_start; band < band_end; band++) {
+ int tmp = s->db_per_bit - band_psd[band];
if (tmp > 0) {
- excite[bin] += tmp >> 2;
+ excite[band] += tmp >> 2;
}
- mask[bin] = FFMAX(ff_ac3_hearing_threshold_tab[bin >> s->sr_shift][s->sr_code], excite[bin]);
+ mask[band] = FFMAX(ff_ac3_hearing_threshold_tab[band >> s->sr_shift][s->sr_code], excite[band]);
}
/* delta bit allocation */
if (dba_mode == DBA_REUSE || dba_mode == DBA_NEW) {
- int band, seg, delta;
- if (dba_nsegs >= 8)
+ int i, seg, delta;
+ if (dba_nsegs > 8)
return -1;
- band = 0;
+ band = band_start;
for (seg = 0; seg < dba_nsegs; seg++) {
band += dba_offsets[seg];
- if (band >= 50 || dba_lengths[seg] > 50-band)
+ if (band >= AC3_CRITICAL_BANDS || dba_lengths[seg] > AC3_CRITICAL_BANDS-band)
return -1;
if (dba_values[seg] >= 4) {
delta = (dba_values[seg] - 3) << 7;
} else {
delta = (dba_values[seg] - 4) << 7;
}
- for (k = 0; k < dba_lengths[seg]; k++) {
- mask[band] += delta;
- band++;
+ for (i = 0; i < dba_lengths[seg]; i++) {
+ mask[band++] += delta;
}
}
}
return 0;
}
-void ff_ac3_bit_alloc_calc_bap(int16_t *mask, int16_t *psd, int start, int end,
- int snr_offset, int floor,
- const uint8_t *bap_tab, uint8_t *bap)
-{
- int i, j, k, end1, v, address;
-
- /* special case, if snr offset is -960, set all bap's to zero */
- if(snr_offset == -960) {
- memset(bap, 0, 256);
- return;
- }
-
- i = start;
- j = bin_to_band_tab[start];
- do {
- v = (FFMAX(mask[j] - snr_offset - floor, 0) & 0x1FE0) + floor;
- end1 = FFMIN(band_start_tab[j] + ff_ac3_critical_band_size_tab[j], end);
- for (k = i; k < end1; k++) {
- address = av_clip((psd[i] - v) >> 5, 0, 63);
- bap[i] = bap_tab[address];
- i++;
- }
- } while (end > band_start_tab[j++]);
-}
-
-/* AC-3 bit allocation. The algorithm is the one described in the AC-3
- spec. */
-void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap,
- int8_t *exp, int start, int end,
- int snr_offset, int fast_gain, int is_lfe,
- int dba_mode, int dba_nsegs,
- uint8_t *dba_offsets, uint8_t *dba_lengths,
- uint8_t *dba_values)
-{
- int16_t psd[256]; /* scaled exponents */
- int16_t band_psd[50]; /* interpolated exponents */
- int16_t mask[50]; /* masking value */
-
- ff_ac3_bit_alloc_calc_psd(exp, start, end, psd, band_psd);
-
- ff_ac3_bit_alloc_calc_mask(s, band_psd, start, end, fast_gain, is_lfe,
- dba_mode, dba_nsegs, dba_offsets, dba_lengths, dba_values,
- mask);
-
- ff_ac3_bit_alloc_calc_bap(mask, psd, start, end, snr_offset, s->floor,
- ff_ac3_bap_tab, bap);
-}
-
/**
- * Initializes some tables.
+ * Initialize some tables.
* note: This function must remain thread safe because it is called by the
* AVParser init code.
*/
-av_cold void ac3_common_init(void)
+av_cold void ff_ac3_common_init(void)
{
#if !CONFIG_HARDCODED_TABLES
- int i, j, k, l, v;
- /* compute bndtab and masktab from bandsz */
- k = 0;
- l = 0;
- for(i=0;i<50;i++) {
- band_start_tab[i] = l;
- v = ff_ac3_critical_band_size_tab[i];
- for(j=0;j<v;j++) bin_to_band_tab[k++]=i;
- l += v;
+ /* compute ff_ac3_bin_to_band_tab from ff_ac3_band_start_tab */
+ int bin = 0, band;
+ for (band = 0; band < AC3_CRITICAL_BANDS; band++) {
+ int band_end = ff_ac3_band_start_tab[band+1];
+ while (bin < band_end)
+ ff_ac3_bin_to_band_tab[bin++] = band;
}
- band_start_tab[50] = l;
#endif /* !CONFIG_HARDCODED_TABLES */
}
projects / ffmpeg / blobdiff