* 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)
/* PSD integration */
bin = start;
- band = bin_to_band_tab[start];
+ band = ff_ac3_bin_to_band_tab[start];
do {
int v = psd[bin++];
- int band_end = FFMIN(band_start_tab[band+1], end);
+ 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[bin]) >> 1, 255);
- v = FFMAX(v, psd[bin]) + 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[band++] = v;
- } while (end > band_start_tab[band]);
+ } 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 */
+ int16_t excite[AC3_CRITICAL_BANDS]; /* excitation */
int band;
int band_start, band_end, begin, end1;
int lowcomp, fastleak, slowleak;
/* excitation function */
- band_start = bin_to_band_tab[start];
- band_end = 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 (band_start == 0) {
lowcomp = 0;
if (dba_mode == DBA_REUSE || dba_mode == DBA_NEW) {
int i, seg, delta;
- if (dba_nsegs >= 8)
+ 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;
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 bin, band;
-
- /* special case, if snr offset is -960, set all bap's to zero */
- if (snr_offset == -960) {
- memset(bap, 0, 256);
- return;
- }
-
- bin = start;
- band = bin_to_band_tab[start];
- do {
- int m = (FFMAX(mask[band] - snr_offset - floor, 0) & 0x1FE0) + floor;
- int band_end = FFMIN(band_start_tab[band] + ff_ac3_critical_band_size_tab[band], end);
- for (; bin < band_end; bin++) {
- int address = av_clip((psd[bin] - m) >> 5, 0, 63);
- bap[bin] = bap_tab[address];
- }
- } while (end > band_start_tab[band++]);
-}
-
-/* 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
- /* compute bndtab and masktab from bandsz */
+ /* compute ff_ac3_bin_to_band_tab from ff_ac3_band_start_tab */
int bin = 0, band;
- for (band = 0; band < 50; band++) {
- int band_end = bin + ff_ac3_critical_band_size_tab[band];
- band_start_tab[band] = bin;
+ for (band = 0; band < AC3_CRITICAL_BANDS; band++) {
+ int band_end = ff_ac3_band_start_tab[band+1];
while (bin < band_end)
- bin_to_band_tab[bin++] = band;
+ ff_ac3_bin_to_band_tab[bin++] = band;
}
- band_start_tab[50] = bin;
#endif /* !CONFIG_HARDCODED_TABLES */
}
projects / ffmpeg / blobdiff