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FFmpeg/libavcodec/ac3enc.c
Anton Khirnov 2df0c32ea1 lavc: use a separate field for exporting audio encoder padding 
Currently, the amount of padding inserted at the beginning by some audio
encoders, is exported through AVCodecContext.delay. However
- the term 'delay' is heavily overloaded and can have multiple different
  meanings even in the case of audio encoding.
- this field has entirely different meanings, depending on whether the
  codec context is used for encoding or decoding (and has yet another
  different meaning for video), preventing generic handling of the codec
  context.

Therefore, add a new field -- AVCodecContext.initial_padding. It could
conceivably be used for decoding as well at a later point.
2014-10-13 19:09:01 +00:00

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/*
* The simplest AC-3 encoder
* Copyright (c) 2000 Fabrice Bellard
* Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
* Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
*
* This file is part of Libav.
*
* 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.
*
* 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* The simplest AC-3 encoder.
*/
#include <stdint.h>
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/crc.h"
#include "libavutil/internal.h"
#include "libavutil/opt.h"
#include "avcodec.h"
#include "me_cmp.h"
#include "put_bits.h"
#include "audiodsp.h"
#include "ac3dsp.h"
#include "ac3.h"
#include "fft.h"
#include "ac3enc.h"
#include "eac3enc.h"
typedef struct AC3Mant {
int16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4
int mant1_cnt, mant2_cnt, mant4_cnt; ///< mantissa counts for bap=1,2,4
} AC3Mant;
#define CMIXLEV_NUM_OPTIONS 3
static const float cmixlev_options[CMIXLEV_NUM_OPTIONS] = {
LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB
};
#define SURMIXLEV_NUM_OPTIONS 3
static const float surmixlev_options[SURMIXLEV_NUM_OPTIONS] = {
LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO
};
#define EXTMIXLEV_NUM_OPTIONS 8
static const float extmixlev_options[EXTMIXLEV_NUM_OPTIONS] = {
LEVEL_PLUS_3DB, LEVEL_PLUS_1POINT5DB, LEVEL_ONE, LEVEL_MINUS_4POINT5DB,
LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB, LEVEL_MINUS_6DB, LEVEL_ZERO
};
/**
* LUT for number of exponent groups.
* exponent_group_tab[coupling][exponent strategy-1][number of coefficients]
*/
static uint8_t exponent_group_tab[2][3][256];
/**
* List of supported channel layouts.
*/
const uint64_t ff_ac3_channel_layouts[19] = {
AV_CH_LAYOUT_MONO,
AV_CH_LAYOUT_STEREO,
AV_CH_LAYOUT_2_1,
AV_CH_LAYOUT_SURROUND,
AV_CH_LAYOUT_2_2,
AV_CH_LAYOUT_QUAD,
AV_CH_LAYOUT_4POINT0,
AV_CH_LAYOUT_5POINT0,
AV_CH_LAYOUT_5POINT0_BACK,
(AV_CH_LAYOUT_MONO | AV_CH_LOW_FREQUENCY),
(AV_CH_LAYOUT_STEREO | AV_CH_LOW_FREQUENCY),
(AV_CH_LAYOUT_2_1 | AV_CH_LOW_FREQUENCY),
(AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
(AV_CH_LAYOUT_2_2 | AV_CH_LOW_FREQUENCY),
(AV_CH_LAYOUT_QUAD | AV_CH_LOW_FREQUENCY),
(AV_CH_LAYOUT_4POINT0 | AV_CH_LOW_FREQUENCY),
AV_CH_LAYOUT_5POINT1,
AV_CH_LAYOUT_5POINT1_BACK,
0
};
/**
* LUT to select the bandwidth code based on the bit rate, sample rate, and
* number of full-bandwidth channels.
* bandwidth_tab[fbw_channels-1][sample rate code][bit rate code]
*/
static const uint8_t ac3_bandwidth_tab[5][3][19] = {
// 32 40 48 56 64 80 96 112 128 160 192 224 256 320 384 448 512 576 640
{ { 0, 0, 0, 12, 16, 32, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48 },
{ 0, 0, 0, 16, 20, 36, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56, 56 },
{ 0, 0, 0, 32, 40, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60 } },
{ { 0, 0, 0, 0, 0, 0, 0, 20, 24, 32, 48, 48, 48, 48, 48, 48, 48, 48, 48 },
{ 0, 0, 0, 0, 0, 0, 4, 24, 28, 36, 56, 56, 56, 56, 56, 56, 56, 56, 56 },
{ 0, 0, 0, 0, 0, 0, 20, 44, 52, 60, 60, 60, 60, 60, 60, 60, 60, 60, 60 } },
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 16, 24, 32, 40, 48, 48, 48, 48, 48, 48 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 4, 20, 28, 36, 44, 56, 56, 56, 56, 56, 56 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 20, 40, 48, 60, 60, 60, 60, 60, 60, 60, 60 } },
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, 24, 32, 48, 48, 48, 48, 48, 48 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 16, 28, 36, 56, 56, 56, 56, 56, 56 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 32, 48, 60, 60, 60, 60, 60, 60, 60 } },
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 20, 32, 40, 48, 48, 48, 48 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, 24, 36, 44, 56, 56, 56, 56 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 28, 44, 60, 60, 60, 60, 60, 60 } }
};
/**
* LUT to select the coupling start band based on the bit rate, sample rate, and
* number of full-bandwidth channels. -1 = coupling off
* ac3_coupling_start_tab[channel_mode-2][sample rate code][bit rate code]
*
* TODO: more testing for optimal parameters.
* multi-channel tests at 44.1kHz and 32kHz.
*/
static const int8_t ac3_coupling_start_tab[6][3][19] = {
// 32 40 48 56 64 80 96 112 128 160 192 224 256 320 384 448 512 576 640
// 2/0
{ { 0, 0, 0, 0, 0, 0, 0, 1, 1, 7, 8, 11, 12, -1, -1, -1, -1, -1, -1 },
{ 0, 0, 0, 0, 0, 0, 1, 3, 5, 7, 10, 12, 13, -1, -1, -1, -1, -1, -1 },
{ 0, 0, 0, 0, 1, 2, 2, 9, 13, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
// 3/0
{ { 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 6, 9, 11, 12, 13, -1, -1, -1, -1 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 6, 9, 11, 12, 13, -1, -1, -1, -1 },
{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
// 2/1 - untested
{ { 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 6, 9, 11, 12, 13, -1, -1, -1, -1 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 6, 9, 11, 12, 13, -1, -1, -1, -1 },
{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
// 3/1
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 2, 10, 11, 11, 12, 12, 14, -1 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 2, 10, 11, 11, 12, 12, 14, -1 },
{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
// 2/2 - untested
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 2, 10, 11, 11, 12, 12, 14, -1 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 2, 10, 11, 11, 12, 12, 14, -1 },
{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
// 3/2
{ { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 8, 11, 12, 12, -1, -1 },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 8, 11, 12, 12, -1, -1 },
{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
};
/**
* Adjust the frame size to make the average bit rate match the target bit rate.
* This is only needed for 11025, 22050, and 44100 sample rates or any E-AC-3.
*
* @param s AC-3 encoder private context
*/
void ff_ac3_adjust_frame_size(AC3EncodeContext *s)
{
while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
s->bits_written -= s->bit_rate;
s->samples_written -= s->sample_rate;
}
s->frame_size = s->frame_size_min +
2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
s->bits_written += s->frame_size * 8;
s->samples_written += AC3_BLOCK_SIZE * s->num_blocks;
}
/**
* Set the initial coupling strategy parameters prior to coupling analysis.
*
* @param s AC-3 encoder private context
*/
void ff_ac3_compute_coupling_strategy(AC3EncodeContext *s)
{
int blk, ch;
int got_cpl_snr;
int num_cpl_blocks;
/* set coupling use flags for each block/channel */
/* TODO: turn coupling on/off and adjust start band based on bit usage */
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
for (ch = 1; ch <= s->fbw_channels; ch++)
block->channel_in_cpl[ch] = s->cpl_on;
}
/* enable coupling for each block if at least 2 channels have coupling
enabled for that block */
got_cpl_snr = 0;
num_cpl_blocks = 0;
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
block->num_cpl_channels = 0;
for (ch = 1; ch <= s->fbw_channels; ch++)
block->num_cpl_channels += block->channel_in_cpl[ch];
block->cpl_in_use = block->num_cpl_channels > 1;
num_cpl_blocks += block->cpl_in_use;
if (!block->cpl_in_use) {
block->num_cpl_channels = 0;
for (ch = 1; ch <= s->fbw_channels; ch++)
block->channel_in_cpl[ch] = 0;
}
block->new_cpl_strategy = !blk;
if (blk) {
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (block->channel_in_cpl[ch] != s->blocks[blk-1].channel_in_cpl[ch]) {
block->new_cpl_strategy = 1;
break;
}
}
}
block->new_cpl_leak = block->new_cpl_strategy;
if (!blk || (block->cpl_in_use && !got_cpl_snr)) {
block->new_snr_offsets = 1;
if (block->cpl_in_use)
got_cpl_snr = 1;
} else {
block->new_snr_offsets = 0;
}
}
if (!num_cpl_blocks)
s->cpl_on = 0;
/* set bandwidth for each channel */
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (block->channel_in_cpl[ch])
block->end_freq[ch] = s->start_freq[CPL_CH];
else
block->end_freq[ch] = s->bandwidth_code * 3 + 73;
}
}
}
/**
* Apply stereo rematrixing to coefficients based on rematrixing flags.
*
* @param s AC-3 encoder private context
*/
void ff_ac3_apply_rematrixing(AC3EncodeContext *s)
{
int nb_coefs;
int blk, bnd, i;
int start, end;
uint8_t *flags;
if (!s->rematrixing_enabled)
return;
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
if (block->new_rematrixing_strategy)
flags = block->rematrixing_flags;
nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
if (flags[bnd]) {
start = ff_ac3_rematrix_band_tab[bnd];
end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
for (i = start; i < end; i++) {
int32_t lt = block->fixed_coef[1][i];
int32_t rt = block->fixed_coef[2][i];
block->fixed_coef[1][i] = (lt + rt) >> 1;
block->fixed_coef[2][i] = (lt - rt) >> 1;
}
}
}
}
}
/*
* Initialize exponent tables.
*/
static av_cold void exponent_init(AC3EncodeContext *s)
{
int expstr, i, grpsize;
for (expstr = EXP_D15-1; expstr <= EXP_D45-1; expstr++) {
grpsize = 3 << expstr;
for (i = 12; i < 256; i++) {
exponent_group_tab[0][expstr][i] = (i + grpsize - 4) / grpsize;
exponent_group_tab[1][expstr][i] = (i ) / grpsize;
}
}
/* LFE */
exponent_group_tab[0][0][7] = 2;
if (CONFIG_EAC3_ENCODER && s->eac3)
ff_eac3_exponent_init();
}
/*
* Extract exponents from the MDCT coefficients.
*/
static void extract_exponents(AC3EncodeContext *s)
{
int ch = !s->cpl_on;
int chan_size = AC3_MAX_COEFS * s->num_blocks * (s->channels - ch + 1);
AC3Block *block = &s->blocks[0];
s->ac3dsp.extract_exponents(block->exp[ch], block->fixed_coef[ch], chan_size);
}
/**
* Exponent Difference Threshold.
* New exponents are sent if their SAD exceed this number.
*/
#define EXP_DIFF_THRESHOLD 500
/**
* Table used to select exponent strategy based on exponent reuse block interval.
*/
static const uint8_t exp_strategy_reuse_tab[4][6] = {
{ EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
{ EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
{ EXP_D25, EXP_D25, EXP_D15, EXP_D15, EXP_D15, EXP_D15 },
{ EXP_D45, EXP_D25, EXP_D25, EXP_D15, EXP_D15, EXP_D15 }
};
/*
* Calculate exponent strategies for all channels.
* Array arrangement is reversed to simplify the per-channel calculation.
*/
static void compute_exp_strategy(AC3EncodeContext *s)
{
int ch, blk, blk1;
for (ch = !s->cpl_on; ch <= s->fbw_channels; ch++) {
uint8_t *exp_strategy = s->exp_strategy[ch];
uint8_t *exp = s->blocks[0].exp[ch];
int exp_diff;
/* estimate if the exponent variation & decide if they should be
reused in the next frame */
exp_strategy[0] = EXP_NEW;
exp += AC3_MAX_COEFS;
for (blk = 1; blk < s->num_blocks; blk++, exp += AC3_MAX_COEFS) {
if (ch == CPL_CH) {
if (!s->blocks[blk-1].cpl_in_use) {
exp_strategy[blk] = EXP_NEW;
continue;
} else if (!s->blocks[blk].cpl_in_use) {
exp_strategy[blk] = EXP_REUSE;
continue;
}
} else if (s->blocks[blk].channel_in_cpl[ch] != s->blocks[blk-1].channel_in_cpl[ch]) {
exp_strategy[blk] = EXP_NEW;
continue;
}
exp_diff = s->mecc.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
exp_strategy[blk] = EXP_REUSE;
if (ch == CPL_CH && exp_diff > (EXP_DIFF_THRESHOLD * (s->blocks[blk].end_freq[ch] - s->start_freq[ch]) / AC3_MAX_COEFS))
exp_strategy[blk] = EXP_NEW;
else if (ch > CPL_CH && exp_diff > EXP_DIFF_THRESHOLD)
exp_strategy[blk] = EXP_NEW;
}
/* now select the encoding strategy type : if exponents are often
recoded, we use a coarse encoding */
blk = 0;
while (blk < s->num_blocks) {
blk1 = blk + 1;
while (blk1 < s->num_blocks && exp_strategy[blk1] == EXP_REUSE)
blk1++;
exp_strategy[blk] = exp_strategy_reuse_tab[s->num_blks_code][blk1-blk-1];
blk = blk1;
}
}
if (s->lfe_on) {
ch = s->lfe_channel;
s->exp_strategy[ch][0] = EXP_D15;
for (blk = 1; blk < s->num_blocks; blk++)
s->exp_strategy[ch][blk] = EXP_REUSE;
}
/* for E-AC-3, determine frame exponent strategy */
if (CONFIG_EAC3_ENCODER && s->eac3)
ff_eac3_get_frame_exp_strategy(s);
}
/**
* Update the exponents so that they are the ones the decoder will decode.
*
* @param[in,out] exp array of exponents for 1 block in 1 channel
* @param nb_exps number of exponents in active bandwidth
* @param exp_strategy exponent strategy for the block
* @param cpl indicates if the block is in the coupling channel
*/
static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy,
int cpl)
{
int nb_groups, i, k;
nb_groups = exponent_group_tab[cpl][exp_strategy-1][nb_exps] * 3;
/* for each group, compute the minimum exponent */
switch(exp_strategy) {
case EXP_D25:
for (i = 1, k = 1-cpl; i <= nb_groups; i++) {
uint8_t exp_min = exp[k];
if (exp[k+1] < exp_min)
exp_min = exp[k+1];
exp[i-cpl] = exp_min;
k += 2;
}
break;
case EXP_D45:
for (i = 1, k = 1-cpl; i <= nb_groups; i++) {
uint8_t exp_min = exp[k];
if (exp[k+1] < exp_min)
exp_min = exp[k+1];
if (exp[k+2] < exp_min)
exp_min = exp[k+2];
if (exp[k+3] < exp_min)
exp_min = exp[k+3];
exp[i-cpl] = exp_min;
k += 4;
}
break;
}
/* constraint for DC exponent */
if (!cpl && exp[0] > 15)
exp[0] = 15;
/* decrease the delta between each groups to within 2 so that they can be
differentially encoded */
for (i = 1; i <= nb_groups; i++)
exp[i] = FFMIN(exp[i], exp[i-1] + 2);
i--;
while (--i >= 0)
exp[i] = FFMIN(exp[i], exp[i+1] + 2);
if (cpl)
exp[-1] = exp[0] & ~1;
/* now we have the exponent values the decoder will see */
switch (exp_strategy) {
case EXP_D25:
for (i = nb_groups, k = (nb_groups * 2)-cpl; i > 0; i--) {
uint8_t exp1 = exp[i-cpl];
exp[k--] = exp1;
exp[k--] = exp1;
}
break;
case EXP_D45:
for (i = nb_groups, k = (nb_groups * 4)-cpl; i > 0; i--) {
exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i-cpl];
k -= 4;
}
break;
}
}
/*
* Encode exponents from original extracted form to what the decoder will see.
* This copies and groups exponents based on exponent strategy and reduces
* deltas between adjacent exponent groups so that they can be differentially
* encoded.
*/
static void encode_exponents(AC3EncodeContext *s)
{
int blk, blk1, ch, cpl;
uint8_t *exp, *exp_strategy;
int nb_coefs, num_reuse_blocks;
for (ch = !s->cpl_on; ch <= s->channels; ch++) {
exp = s->blocks[0].exp[ch] + s->start_freq[ch];
exp_strategy = s->exp_strategy[ch];
cpl = (ch == CPL_CH);
blk = 0;
while (blk < s->num_blocks) {
AC3Block *block = &s->blocks[blk];
if (cpl && !block->cpl_in_use) {
exp += AC3_MAX_COEFS;
blk++;
continue;
}
nb_coefs = block->end_freq[ch] - s->start_freq[ch];
blk1 = blk + 1;
/* count the number of EXP_REUSE blocks after the current block
and set exponent reference block numbers */
s->exp_ref_block[ch][blk] = blk;
while (blk1 < s->num_blocks && exp_strategy[blk1] == EXP_REUSE) {
s->exp_ref_block[ch][blk1] = blk;
blk1++;
}
num_reuse_blocks = blk1 - blk - 1;
/* for the EXP_REUSE case we select the min of the exponents */
s->ac3dsp.ac3_exponent_min(exp-s->start_freq[ch], num_reuse_blocks,
AC3_MAX_COEFS);
encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk], cpl);
exp += AC3_MAX_COEFS * (num_reuse_blocks + 1);
blk = blk1;
}
}
/* reference block numbers have been changed, so reset ref_bap_set */
s->ref_bap_set = 0;
}
/*
* Count exponent bits based on bandwidth, coupling, and exponent strategies.
*/
static int count_exponent_bits(AC3EncodeContext *s)
{
int blk, ch;
int nb_groups, bit_count;
bit_count = 0;
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
int exp_strategy = s->exp_strategy[ch][blk];
int cpl = (ch == CPL_CH);
int nb_coefs = block->end_freq[ch] - s->start_freq[ch];
if (exp_strategy == EXP_REUSE)
continue;
nb_groups = exponent_group_tab[cpl][exp_strategy-1][nb_coefs];
bit_count += 4 + (nb_groups * 7);
}
}
return bit_count;
}
/**
* Group exponents.
* 3 delta-encoded exponents are in each 7-bit group. The number of groups
* varies depending on exponent strategy and bandwidth.
*
* @param s AC-3 encoder private context
*/
void ff_ac3_group_exponents(AC3EncodeContext *s)
{
int blk, ch, i, cpl;
int group_size, nb_groups;
uint8_t *p;
int delta0, delta1, delta2;
int exp0, exp1;
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
int exp_strategy = s->exp_strategy[ch][blk];
if (exp_strategy == EXP_REUSE)
continue;
cpl = (ch == CPL_CH);
group_size = exp_strategy + (exp_strategy == EXP_D45);
nb_groups = exponent_group_tab[cpl][exp_strategy-1][block->end_freq[ch]-s->start_freq[ch]];
p = block->exp[ch] + s->start_freq[ch] - cpl;
/* DC exponent */
exp1 = *p++;
block->grouped_exp[ch][0] = exp1;
/* remaining exponents are delta encoded */
for (i = 1; i <= nb_groups; i++) {
/* merge three delta in one code */
exp0 = exp1;
exp1 = p[0];
p += group_size;
delta0 = exp1 - exp0 + 2;
av_assert2(delta0 >= 0 && delta0 <= 4);
exp0 = exp1;
exp1 = p[0];
p += group_size;
delta1 = exp1 - exp0 + 2;
av_assert2(delta1 >= 0 && delta1 <= 4);
exp0 = exp1;
exp1 = p[0];
p += group_size;
delta2 = exp1 - exp0 + 2;
av_assert2(delta2 >= 0 && delta2 <= 4);
block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
}
}
}
}
/**
* Calculate final exponents from the supplied MDCT coefficients and exponent shift.
* Extract exponents from MDCT coefficients, calculate exponent strategies,
* and encode final exponents.
*
* @param s AC-3 encoder private context
*/
void ff_ac3_process_exponents(AC3EncodeContext *s)
{
extract_exponents(s);
compute_exp_strategy(s);
encode_exponents(s);
emms_c();
}
/*
* Count frame bits that are based solely on fixed parameters.
* This only has to be run once when the encoder is initialized.
*/
static void count_frame_bits_fixed(AC3EncodeContext *s)
{
static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
int blk;
int frame_bits;
/* assumptions:
* no dynamic range codes
* bit allocation parameters do not change between blocks
* no delta bit allocation
* no skipped data
* no auxiliary data
* no E-AC-3 metadata
*/
/* header */
frame_bits = 16; /* sync info */
if (s->eac3) {
/* bitstream info header */
frame_bits += 35;
frame_bits += 1 + 1;
if (s->num_blocks != 0x6)
frame_bits++;
frame_bits++;
/* audio frame header */
if (s->num_blocks == 6)
frame_bits += 2;
frame_bits += 10;
/* exponent strategy */
if (s->use_frame_exp_strategy)
frame_bits += 5 * s->fbw_channels;
else
frame_bits += s->num_blocks * 2 * s->fbw_channels;
if (s->lfe_on)
frame_bits += s->num_blocks;
/* converter exponent strategy */
if (s->num_blks_code != 0x3)
frame_bits++;
else
frame_bits += s->fbw_channels * 5;
/* snr offsets */
frame_bits += 10;
/* block start info */
if (s->num_blocks != 1)
frame_bits++;
} else {
frame_bits += 49;
frame_bits += frame_bits_inc[s->channel_mode];
}
/* audio blocks */
for (blk = 0; blk < s->num_blocks; blk++) {
if (!s->eac3) {
/* block switch flags */
frame_bits += s->fbw_channels;
/* dither flags */
frame_bits += s->fbw_channels;
}
/* dynamic range */
frame_bits++;
/* spectral extension */
if (s->eac3)
frame_bits++;
if (!s->eac3) {
/* exponent strategy */
frame_bits += 2 * s->fbw_channels;
if (s->lfe_on)
frame_bits++;
/* bit allocation params */
frame_bits++;
if (!blk)
frame_bits += 2 + 2 + 2 + 2 + 3;
}
/* converter snr offset */
if (s->eac3)
frame_bits++;
if (!s->eac3) {
/* delta bit allocation */
frame_bits++;
/* skipped data */
frame_bits++;
}
}
/* auxiliary data */
frame_bits++;
/* CRC */
frame_bits += 1 + 16;
s->frame_bits_fixed = frame_bits;
}
/*
* Initialize bit allocation.
* Set default parameter codes and calculate parameter values.
*/
static av_cold void bit_alloc_init(AC3EncodeContext *s)
{
int ch;
/* init default parameters */
s->slow_decay_code = 2;
s->fast_decay_code = 1;
s->slow_gain_code = 1;
s->db_per_bit_code = s->eac3 ? 2 : 3;
s->floor_code = 7;
for (ch = 0; ch <= s->channels; ch++)
s->fast_gain_code[ch] = 4;
/* initial snr offset */
s->coarse_snr_offset = 40;
/* compute real values */
/* currently none of these values change during encoding, so we can just
set them once at initialization */
s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
s->bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s->slow_gain_code];
s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
s->bit_alloc.floor = ff_ac3_floor_tab[s->floor_code];
s->bit_alloc.cpl_fast_leak = 0;
s->bit_alloc.cpl_slow_leak = 0;
count_frame_bits_fixed(s);
}
/*
* Count the bits used to encode the frame, minus exponents and mantissas.
* Bits based on fixed parameters have already been counted, so now we just
* have to add the bits based on parameters that change during encoding.
*/
static void count_frame_bits(AC3EncodeContext *s)
{
AC3EncOptions *opt = &s->options;
int blk, ch;
int frame_bits = 0;
/* header */
if (s->eac3) {
if (opt->eac3_mixing_metadata) {
if (s->channel_mode > AC3_CHMODE_STEREO)
frame_bits += 2;
if (s->has_center)
frame_bits += 6;
if (s->has_surround)
frame_bits += 6;
frame_bits += s->lfe_on;
frame_bits += 1 + 1 + 2;
if (s->channel_mode < AC3_CHMODE_STEREO)
frame_bits++;
frame_bits++;
}
if (opt->eac3_info_metadata) {
frame_bits += 3 + 1 + 1;
if (s->channel_mode == AC3_CHMODE_STEREO)
frame_bits += 2 + 2;
if (s->channel_mode >= AC3_CHMODE_2F2R)
frame_bits += 2;
frame_bits++;
if (opt->audio_production_info)
frame_bits += 5 + 2 + 1;
frame_bits++;
}
/* coupling */
if (s->channel_mode > AC3_CHMODE_MONO) {
frame_bits++;
for (blk = 1; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
frame_bits++;
if (block->new_cpl_strategy)
frame_bits++;
}
}
/* coupling exponent strategy */
if (s->cpl_on) {
if (s->use_frame_exp_strategy) {
frame_bits += 5 * s->cpl_on;
} else {
for (blk = 0; blk < s->num_blocks; blk++)
frame_bits += 2 * s->blocks[blk].cpl_in_use;
}
}
} else {
if (opt->audio_production_info)
frame_bits += 7;
if (s->bitstream_id == 6) {
if (opt->extended_bsi_1)
frame_bits += 14;
if (opt->extended_bsi_2)
frame_bits += 14;
}
}
/* audio blocks */
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
/* coupling strategy */
if (!s->eac3)
frame_bits++;
if (block->new_cpl_strategy) {
if (!s->eac3)
frame_bits++;
if (block->cpl_in_use) {
if (s->eac3)
frame_bits++;
if (!s->eac3 || s->channel_mode != AC3_CHMODE_STEREO)
frame_bits += s->fbw_channels;
if (s->channel_mode == AC3_CHMODE_STEREO)
frame_bits++;
frame_bits += 4 + 4;
if (s->eac3)
frame_bits++;
else
frame_bits += s->num_cpl_subbands - 1;
}
}
/* coupling coordinates */
if (block->cpl_in_use) {
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (block->channel_in_cpl[ch]) {
if (!s->eac3 || block->new_cpl_coords[ch] != 2)
frame_bits++;
if (block->new_cpl_coords[ch]) {
frame_bits += 2;
frame_bits += (4 + 4) * s->num_cpl_bands;
}
}
}
}
/* stereo rematrixing */
if (s->channel_mode == AC3_CHMODE_STEREO) {
if (!s->eac3 || blk > 0)
frame_bits++;
if (s->blocks[blk].new_rematrixing_strategy)
frame_bits += block->num_rematrixing_bands;
}
/* bandwidth codes & gain range */
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (s->exp_strategy[ch][blk] != EXP_REUSE) {
if (!block->channel_in_cpl[ch])
frame_bits += 6;
frame_bits += 2;
}
}
/* coupling exponent strategy */
if (!s->eac3 && block->cpl_in_use)
frame_bits += 2;
/* snr offsets and fast gain codes */
if (!s->eac3) {
frame_bits++;
if (block->new_snr_offsets)
frame_bits += 6 + (s->channels + block->cpl_in_use) * (4 + 3);
}
/* coupling leak info */
if (block->cpl_in_use) {
if (!s->eac3 || block->new_cpl_leak != 2)
frame_bits++;
if (block->new_cpl_leak)
frame_bits += 3 + 3;
}
}
s->frame_bits = s->frame_bits_fixed + frame_bits;
}
/*
* Calculate masking curve based on the final exponents.
* Also calculate the power spectral densities to use in future calculations.
*/
static void bit_alloc_masking(AC3EncodeContext *s)
{
int blk, ch;
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
/* We only need psd and mask for calculating bap.
Since we currently do not calculate bap when exponent
strategy is EXP_REUSE we do not need to calculate psd or mask. */
if (s->exp_strategy[ch][blk] != EXP_REUSE) {
ff_ac3_bit_alloc_calc_psd(block->exp[ch], s->start_freq[ch],
block->end_freq[ch], block->psd[ch],
block->band_psd[ch]);
ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
s->start_freq[ch], block->end_freq[ch],
ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
ch == s->lfe_channel,
DBA_NONE, 0, NULL, NULL, NULL,
block->mask[ch]);
}
}
}
}
/*
* Ensure that bap for each block and channel point to the current bap_buffer.
* They may have been switched during the bit allocation search.
*/
static void reset_block_bap(AC3EncodeContext *s)
{
int blk, ch;
uint8_t *ref_bap;
if (s->ref_bap[0][0] == s->bap_buffer && s->ref_bap_set)
return;
ref_bap = s->bap_buffer;
for (ch = 0; ch <= s->channels; ch++) {
for (blk = 0; blk < s->num_blocks; blk++)
s->ref_bap[ch][blk] = ref_bap + AC3_MAX_COEFS * s->exp_ref_block[ch][blk];
ref_bap += AC3_MAX_COEFS * s->num_blocks;
}
s->ref_bap_set = 1;
}
/**
* Initialize mantissa counts.
* These are set so that they are padded to the next whole group size when bits
* are counted in compute_mantissa_size.
*
* @param[in,out] mant_cnt running counts for each bap value for each block
*/
static void count_mantissa_bits_init(uint16_t mant_cnt[AC3_MAX_BLOCKS][16])
{
int blk;
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
memset(mant_cnt[blk], 0, sizeof(mant_cnt[blk]));
mant_cnt[blk][1] = mant_cnt[blk][2] = 2;
mant_cnt[blk][4] = 1;
}
}
/**
* Update mantissa bit counts for all blocks in 1 channel in a given bandwidth
* range.
*
* @param s AC-3 encoder private context
* @param ch channel index
* @param[in,out] mant_cnt running counts for each bap value for each block
* @param start starting coefficient bin
* @param end ending coefficient bin
*/
static void count_mantissa_bits_update_ch(AC3EncodeContext *s, int ch,
uint16_t mant_cnt[AC3_MAX_BLOCKS][16],
int start, int end)
{
int blk;
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
if (ch == CPL_CH && !block->cpl_in_use)
continue;
s->ac3dsp.update_bap_counts(mant_cnt[blk],
s->ref_bap[ch][blk] + start,
FFMIN(end, block->end_freq[ch]) - start);
}
}
/*
* Count the number of mantissa bits in the frame based on the bap values.
*/
static int count_mantissa_bits(AC3EncodeContext *s)
{
int ch, max_end_freq;
LOCAL_ALIGNED_16(uint16_t, mant_cnt, [AC3_MAX_BLOCKS], [16]);
count_mantissa_bits_init(mant_cnt);
max_end_freq = s->bandwidth_code * 3 + 73;
for (ch = !s->cpl_enabled; ch <= s->channels; ch++)
count_mantissa_bits_update_ch(s, ch, mant_cnt, s->start_freq[ch],
max_end_freq);
return s->ac3dsp.compute_mantissa_size(mant_cnt);
}
/**
* Run the bit allocation with a given SNR offset.
* This calculates the bit allocation pointers that will be used to determine
* the quantization of each mantissa.
*
* @param s AC-3 encoder private context
* @param snr_offset SNR offset, 0 to 1023
* @return the number of bits needed for mantissas if the given SNR offset is
* is used.
*/
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
{
int blk, ch;
snr_offset = (snr_offset - 240) << 2;
reset_block_bap(s);
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
/* Currently the only bit allocation parameters which vary across
blocks within a frame are the exponent values. We can take
advantage of that by reusing the bit allocation pointers
whenever we reuse exponents. */
if (s->exp_strategy[ch][blk] != EXP_REUSE) {
s->ac3dsp.bit_alloc_calc_bap(block->mask[ch], block->psd[ch],
s->start_freq[ch], block->end_freq[ch],
snr_offset, s->bit_alloc.floor,
ff_ac3_bap_tab, s->ref_bap[ch][blk]);
}
}
}
return count_mantissa_bits(s);
}
/*
* Constant bitrate bit allocation search.
* Find the largest SNR offset that will allow data to fit in the frame.
*/
static int cbr_bit_allocation(AC3EncodeContext *s)
{
int ch;
int bits_left;
int snr_offset, snr_incr;
bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
if (bits_left < 0)
return AVERROR(EINVAL);
snr_offset = s->coarse_snr_offset << 4;
/* if previous frame SNR offset was 1023, check if current frame can also
use SNR offset of 1023. if so, skip the search. */
if ((snr_offset | s->fine_snr_offset[1]) == 1023) {
if (bit_alloc(s, 1023) <= bits_left)
return 0;
}
while (snr_offset >= 0 &&
bit_alloc(s, snr_offset) > bits_left) {
snr_offset -= 64;
}
if (snr_offset < 0)
return AVERROR(EINVAL);
FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
while (snr_offset + snr_incr <= 1023 &&
bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
snr_offset += snr_incr;
FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
}
}
FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
reset_block_bap(s);
s->coarse_snr_offset = snr_offset >> 4;
for (ch = !s->cpl_on; ch <= s->channels; ch++)
s->fine_snr_offset[ch] = snr_offset & 0xF;
return 0;
}
/*
* Perform bit allocation search.
* Finds the SNR offset value that maximizes quality and fits in the specified
* frame size. Output is the SNR offset and a set of bit allocation pointers
* used to quantize the mantissas.
*/
int ff_ac3_compute_bit_allocation(AC3EncodeContext *s)
{
count_frame_bits(s);
s->exponent_bits = count_exponent_bits(s);
bit_alloc_masking(s);
return cbr_bit_allocation(s);
}
/**
* Symmetric quantization on 'levels' levels.
*
* @param c unquantized coefficient
* @param e exponent
* @param levels number of quantization levels
* @return quantized coefficient
*/
static inline int sym_quant(int c, int e, int levels)
{
int v = (((levels * c) >> (24 - e)) + levels) >> 1;
av_assert2(v >= 0 && v < levels);
return v;
}
/**
* Asymmetric quantization on 2^qbits levels.
*
* @param c unquantized coefficient
* @param e exponent
* @param qbits number of quantization bits
* @return quantized coefficient
*/
static inline int asym_quant(int c, int e, int qbits)
{
int m;
c = (((c << e) >> (24 - qbits)) + 1) >> 1;
m = (1 << (qbits-1));
if (c >= m)
c = m - 1;
av_assert2(c >= -m);
return c;
}
/**
* Quantize a set of mantissas for a single channel in a single block.
*
* @param s Mantissa count context
* @param fixed_coef unquantized fixed-point coefficients
* @param exp exponents
* @param bap bit allocation pointer indices
* @param[out] qmant quantized coefficients
* @param start_freq starting coefficient bin
* @param end_freq ending coefficient bin
*/
static void quantize_mantissas_blk_ch(AC3Mant *s, int32_t *fixed_coef,
uint8_t *exp, uint8_t *bap,
int16_t *qmant, int start_freq,
int end_freq)
{
int i;
for (i = start_freq; i < end_freq; i++) {
int v;
int c = fixed_coef[i];
int e = exp[i];
int b = bap[i];
switch (b) {
case 0:
v = 0;
break;
case 1:
v = sym_quant(c, e, 3);
switch (s->mant1_cnt) {
case 0:
s->qmant1_ptr = &qmant[i];
v = 9 * v;
s->mant1_cnt = 1;
break;
case 1:
*s->qmant1_ptr += 3 * v;
s->mant1_cnt = 2;
v = 128;
break;
default:
*s->qmant1_ptr += v;
s->mant1_cnt = 0;
v = 128;
break;
}
break;
case 2:
v = sym_quant(c, e, 5);
switch (s->mant2_cnt) {
case 0:
s->qmant2_ptr = &qmant[i];
v = 25 * v;
s->mant2_cnt = 1;
break;
case 1:
*s->qmant2_ptr += 5 * v;
s->mant2_cnt = 2;
v = 128;
break;
default:
*s->qmant2_ptr += v;
s->mant2_cnt = 0;
v = 128;
break;
}
break;
case 3:
v = sym_quant(c, e, 7);
break;
case 4:
v = sym_quant(c, e, 11);
switch (s->mant4_cnt) {
case 0:
s->qmant4_ptr = &qmant[i];
v = 11 * v;
s->mant4_cnt = 1;
break;
default:
*s->qmant4_ptr += v;
s->mant4_cnt = 0;
v = 128;
break;
}
break;
case 5:
v = sym_quant(c, e, 15);
break;
case 14:
v = asym_quant(c, e, 14);
break;
case 15:
v = asym_quant(c, e, 16);
break;
default:
v = asym_quant(c, e, b - 1);
break;
}
qmant[i] = v;
}
}
/**
* Quantize mantissas using coefficients, exponents, and bit allocation pointers.
*
* @param s AC-3 encoder private context
*/
void ff_ac3_quantize_mantissas(AC3EncodeContext *s)
{
int blk, ch, ch0=0, got_cpl;
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
AC3Mant m = { 0 };
got_cpl = !block->cpl_in_use;
for (ch = 1; ch <= s->channels; ch++) {
if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
ch0 = ch - 1;
ch = CPL_CH;
got_cpl = 1;
}
quantize_mantissas_blk_ch(&m, block->fixed_coef[ch],
s->blocks[s->exp_ref_block[ch][blk]].exp[ch],
s->ref_bap[ch][blk], block->qmant[ch],
s->start_freq[ch], block->end_freq[ch]);
if (ch == CPL_CH)
ch = ch0;
}
}
}
/*
* Write the AC-3 frame header to the output bitstream.
*/
static void ac3_output_frame_header(AC3EncodeContext *s)
{
AC3EncOptions *opt = &s->options;
put_bits(&s->pb, 16, 0x0b77); /* frame header */
put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
put_bits(&s->pb, 2, s->bit_alloc.sr_code);
put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
put_bits(&s->pb, 5, s->bitstream_id);
put_bits(&s->pb, 3, s->bitstream_mode);
put_bits(&s->pb, 3, s->channel_mode);
if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
put_bits(&s->pb, 2, s->center_mix_level);
if (s->channel_mode & 0x04)
put_bits(&s->pb, 2, s->surround_mix_level);
if (s->channel_mode == AC3_CHMODE_STEREO)
put_bits(&s->pb, 2, opt->dolby_surround_mode);
put_bits(&s->pb, 1, s->lfe_on); /* LFE */
put_bits(&s->pb, 5, -opt->dialogue_level);
put_bits(&s->pb, 1, 0); /* no compression control word */
put_bits(&s->pb, 1, 0); /* no lang code */
put_bits(&s->pb, 1, opt->audio_production_info);
if (opt->audio_production_info) {
put_bits(&s->pb, 5, opt->mixing_level - 80);
put_bits(&s->pb, 2, opt->room_type);
}
put_bits(&s->pb, 1, opt->copyright);
put_bits(&s->pb, 1, opt->original);
if (s->bitstream_id == 6) {
/* alternate bit stream syntax */
put_bits(&s->pb, 1, opt->extended_bsi_1);
if (opt->extended_bsi_1) {
put_bits(&s->pb, 2, opt->preferred_stereo_downmix);
put_bits(&s->pb, 3, s->ltrt_center_mix_level);
put_bits(&s->pb, 3, s->ltrt_surround_mix_level);
put_bits(&s->pb, 3, s->loro_center_mix_level);
put_bits(&s->pb, 3, s->loro_surround_mix_level);
}
put_bits(&s->pb, 1, opt->extended_bsi_2);
if (opt->extended_bsi_2) {
put_bits(&s->pb, 2, opt->dolby_surround_ex_mode);
put_bits(&s->pb, 2, opt->dolby_headphone_mode);
put_bits(&s->pb, 1, opt->ad_converter_type);
put_bits(&s->pb, 9, 0); /* xbsi2 and encinfo : reserved */
}
} else {
put_bits(&s->pb, 1, 0); /* no time code 1 */
put_bits(&s->pb, 1, 0); /* no time code 2 */
}
put_bits(&s->pb, 1, 0); /* no additional bit stream info */
}
/*
* Write one audio block to the output bitstream.
*/
static void output_audio_block(AC3EncodeContext *s, int blk)
{
int ch, i, baie, bnd, got_cpl, ch0;
AC3Block *block = &s->blocks[blk];
/* block switching */
if (!s->eac3) {
for (ch = 0; ch < s->fbw_channels; ch++)
put_bits(&s->pb, 1, 0);
}
/* dither flags */
if (!s->eac3) {
for (ch = 0; ch < s->fbw_channels; ch++)
put_bits(&s->pb, 1, 1);
}
/* dynamic range codes */
put_bits(&s->pb, 1, 0);
/* spectral extension */
if (s->eac3)
put_bits(&s->pb, 1, 0);
/* channel coupling */
if (!s->eac3)
put_bits(&s->pb, 1, block->new_cpl_strategy);
if (block->new_cpl_strategy) {
if (!s->eac3)
put_bits(&s->pb, 1, block->cpl_in_use);
if (block->cpl_in_use) {
int start_sub, end_sub;
if (s->eac3)
put_bits(&s->pb, 1, 0); /* enhanced coupling */
if (!s->eac3 || s->channel_mode != AC3_CHMODE_STEREO) {
for (ch = 1; ch <= s->fbw_channels; ch++)
put_bits(&s->pb, 1, block->channel_in_cpl[ch]);
}
if (s->channel_mode == AC3_CHMODE_STEREO)
put_bits(&s->pb, 1, 0); /* phase flags in use */
start_sub = (s->start_freq[CPL_CH] - 37) / 12;
end_sub = (s->cpl_end_freq - 37) / 12;
put_bits(&s->pb, 4, start_sub);
put_bits(&s->pb, 4, end_sub - 3);
/* coupling band structure */
if (s->eac3) {
put_bits(&s->pb, 1, 0); /* use default */
} else {
for (bnd = start_sub+1; bnd < end_sub; bnd++)
put_bits(&s->pb, 1, ff_eac3_default_cpl_band_struct[bnd]);
}
}
}
/* coupling coordinates */
if (block->cpl_in_use) {
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (block->channel_in_cpl[ch]) {
if (!s->eac3 || block->new_cpl_coords[ch] != 2)
put_bits(&s->pb, 1, block->new_cpl_coords[ch]);
if (block->new_cpl_coords[ch]) {
put_bits(&s->pb, 2, block->cpl_master_exp[ch]);
for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
put_bits(&s->pb, 4, block->cpl_coord_exp [ch][bnd]);
put_bits(&s->pb, 4, block->cpl_coord_mant[ch][bnd]);
}
}
}
}
}
/* stereo rematrixing */
if (s->channel_mode == AC3_CHMODE_STEREO) {
if (!s->eac3 || blk > 0)
put_bits(&s->pb, 1, block->new_rematrixing_strategy);
if (block->new_rematrixing_strategy) {
/* rematrixing flags */
for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++)
put_bits(&s->pb, 1, block->rematrixing_flags[bnd]);
}
}
/* exponent strategy */
if (!s->eac3) {
for (ch = !block->cpl_in_use; ch <= s->fbw_channels; ch++)
put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
if (s->lfe_on)
put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
}
/* bandwidth */
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (s->exp_strategy[ch][blk] != EXP_REUSE && !block->channel_in_cpl[ch])
put_bits(&s->pb, 6, s->bandwidth_code);
}
/* exponents */
for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
int nb_groups;
int cpl = (ch == CPL_CH);
if (s->exp_strategy[ch][blk] == EXP_REUSE)
continue;
/* DC exponent */
put_bits(&s->pb, 4, block->grouped_exp[ch][0] >> cpl);
/* exponent groups */
nb_groups = exponent_group_tab[cpl][s->exp_strategy[ch][blk]-1][block->end_freq[ch]-s->start_freq[ch]];
for (i = 1; i <= nb_groups; i++)
put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
/* gain range info */
if (ch != s->lfe_channel && !cpl)
put_bits(&s->pb, 2, 0);
}
/* bit allocation info */
if (!s->eac3) {
baie = (blk == 0);
put_bits(&s->pb, 1, baie);
if (baie) {
put_bits(&s->pb, 2, s->slow_decay_code);
put_bits(&s->pb, 2, s->fast_decay_code);
put_bits(&s->pb, 2, s->slow_gain_code);
put_bits(&s->pb, 2, s->db_per_bit_code);
put_bits(&s->pb, 3, s->floor_code);
}
}
/* snr offset */
if (!s->eac3) {
put_bits(&s->pb, 1, block->new_snr_offsets);
if (block->new_snr_offsets) {
put_bits(&s->pb, 6, s->coarse_snr_offset);
for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
put_bits(&s->pb, 3, s->fast_gain_code[ch]);
}
}
} else {
put_bits(&s->pb, 1, 0); /* no converter snr offset */
}
/* coupling leak */
if (block->cpl_in_use) {
if (!s->eac3 || block->new_cpl_leak != 2)
put_bits(&s->pb, 1, block->new_cpl_leak);
if (block->new_cpl_leak) {
put_bits(&s->pb, 3, s->bit_alloc.cpl_fast_leak);
put_bits(&s->pb, 3, s->bit_alloc.cpl_slow_leak);
}
}
if (!s->eac3) {
put_bits(&s->pb, 1, 0); /* no delta bit allocation */
put_bits(&s->pb, 1, 0); /* no data to skip */
}
/* mantissas */
got_cpl = !block->cpl_in_use;
for (ch = 1; ch <= s->channels; ch++) {
int b, q;
if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
ch0 = ch - 1;
ch = CPL_CH;
got_cpl = 1;
}
for (i = s->start_freq[ch]; i < block->end_freq[ch]; i++) {
q = block->qmant[ch][i];
b = s->ref_bap[ch][blk][i];
switch (b) {
case 0: break;
case 1: if (q != 128) put_bits (&s->pb, 5, q); break;
case 2: if (q != 128) put_bits (&s->pb, 7, q); break;
case 3: put_sbits(&s->pb, 3, q); break;
case 4: if (q != 128) put_bits (&s->pb, 7, q); break;
case 14: put_sbits(&s->pb, 14, q); break;
case 15: put_sbits(&s->pb, 16, q); break;
default: put_sbits(&s->pb, b-1, q); break;
}
}
if (ch == CPL_CH)
ch = ch0;
}
}
/** CRC-16 Polynomial */
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
{
unsigned int c;
c = 0;
while (a) {
if (a & 1)
c ^= b;
a = a >> 1;
b = b << 1;
if (b & (1 << 16))
b ^= poly;
}
return c;
}
static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
{
unsigned int r;
r = 1;
while (n) {
if (n & 1)
r = mul_poly(r, a, poly);
a = mul_poly(a, a, poly);
n >>= 1;
}
return r;
}
/*
* Fill the end of the frame with 0's and compute the two CRCs.
*/
static void output_frame_end(AC3EncodeContext *s)
{
const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
uint8_t *frame;
frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
/* pad the remainder of the frame with zeros */
av_assert2(s->frame_size * 8 - put_bits_count(&s->pb) >= 18);
flush_put_bits(&s->pb);
frame = s->pb.buf;
pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
av_assert2(pad_bytes >= 0);
if (pad_bytes > 0)
memset(put_bits_ptr(&s->pb), 0, pad_bytes);
if (s->eac3) {
/* compute crc2 */
crc2_partial = av_crc(crc_ctx, 0, frame + 2, s->frame_size - 5);
} else {
/* compute crc1 */
/* this is not so easy because it is at the beginning of the data... */
crc1 = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
AV_WB16(frame + 2, crc1);
/* compute crc2 */
crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
s->frame_size - frame_size_58 - 3);
}
crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
/* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
if (crc2 == 0x770B) {
frame[s->frame_size - 3] ^= 0x1;
crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
}
crc2 = av_bswap16(crc2);
AV_WB16(frame + s->frame_size - 2, crc2);
}
/**
* Write the frame to the output bitstream.
*
* @param s AC-3 encoder private context
* @param frame output data buffer
*/
void ff_ac3_output_frame(AC3EncodeContext *s, unsigned char *frame)
{
int blk;
init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
s->output_frame_header(s);
for (blk = 0; blk < s->num_blocks; blk++)
output_audio_block(s, blk);
output_frame_end(s);
}
static void dprint_options(AC3EncodeContext *s)
{
#ifdef DEBUG
AVCodecContext *avctx = s->avctx;
AC3EncOptions *opt = &s->options;
char strbuf[32];
switch (s->bitstream_id) {
case 6: av_strlcpy(strbuf, "AC-3 (alt syntax)", 32); break;
case 8: av_strlcpy(strbuf, "AC-3 (standard)", 32); break;
case 9: av_strlcpy(strbuf, "AC-3 (dnet half-rate)", 32); break;
case 10: av_strlcpy(strbuf, "AC-3 (dnet quater-rate)", 32); break;
case 16: av_strlcpy(strbuf, "E-AC-3 (enhanced)", 32); break;
default: snprintf(strbuf, 32, "ERROR");
}
av_dlog(avctx, "bitstream_id: %s (%d)\n", strbuf, s->bitstream_id);
av_dlog(avctx, "sample_fmt: %s\n", av_get_sample_fmt_name(avctx->sample_fmt));
av_get_channel_layout_string(strbuf, 32, s->channels, avctx->channel_layout);
av_dlog(avctx, "channel_layout: %s\n", strbuf);
av_dlog(avctx, "sample_rate: %d\n", s->sample_rate);
av_dlog(avctx, "bit_rate: %d\n", s->bit_rate);
av_dlog(avctx, "blocks/frame: %d (code=%d)\n", s->num_blocks, s->num_blks_code);
if (s->cutoff)
av_dlog(avctx, "cutoff: %d\n", s->cutoff);
av_dlog(avctx, "per_frame_metadata: %s\n",
opt->allow_per_frame_metadata?"on":"off");
if (s->has_center)
av_dlog(avctx, "center_mixlev: %0.3f (%d)\n", opt->center_mix_level,
s->center_mix_level);
else
av_dlog(avctx, "center_mixlev: {not written}\n");
if (s->has_surround)
av_dlog(avctx, "surround_mixlev: %0.3f (%d)\n", opt->surround_mix_level,
s->surround_mix_level);
else
av_dlog(avctx, "surround_mixlev: {not written}\n");
if (opt->audio_production_info) {
av_dlog(avctx, "mixing_level: %ddB\n", opt->mixing_level);
switch (opt->room_type) {
case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
case AC3ENC_OPT_LARGE_ROOM: av_strlcpy(strbuf, "large", 32); break;
case AC3ENC_OPT_SMALL_ROOM: av_strlcpy(strbuf, "small", 32); break;
default: snprintf(strbuf, 32, "ERROR (%d)", opt->room_type);
}
av_dlog(avctx, "room_type: %s\n", strbuf);
} else {
av_dlog(avctx, "mixing_level: {not written}\n");
av_dlog(avctx, "room_type: {not written}\n");
}
av_dlog(avctx, "copyright: %s\n", opt->copyright?"on":"off");
av_dlog(avctx, "dialnorm: %ddB\n", opt->dialogue_level);
if (s->channel_mode == AC3_CHMODE_STEREO) {
switch (opt->dolby_surround_mode) {
case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
case AC3ENC_OPT_MODE_ON: av_strlcpy(strbuf, "on", 32); break;
case AC3ENC_OPT_MODE_OFF: av_strlcpy(strbuf, "off", 32); break;
default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_surround_mode);
}
av_dlog(avctx, "dsur_mode: %s\n", strbuf);
} else {
av_dlog(avctx, "dsur_mode: {not written}\n");
}
av_dlog(avctx, "original: %s\n", opt->original?"on":"off");
if (s->bitstream_id == 6) {
if (opt->extended_bsi_1) {
switch (opt->preferred_stereo_downmix) {
case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
case AC3ENC_OPT_DOWNMIX_LTRT: av_strlcpy(strbuf, "ltrt", 32); break;
case AC3ENC_OPT_DOWNMIX_LORO: av_strlcpy(strbuf, "loro", 32); break;
default: snprintf(strbuf, 32, "ERROR (%d)", opt->preferred_stereo_downmix);
}
av_dlog(avctx, "dmix_mode: %s\n", strbuf);
av_dlog(avctx, "ltrt_cmixlev: %0.3f (%d)\n",
opt->ltrt_center_mix_level, s->ltrt_center_mix_level);
av_dlog(avctx, "ltrt_surmixlev: %0.3f (%d)\n",
opt->ltrt_surround_mix_level, s->ltrt_surround_mix_level);
av_dlog(avctx, "loro_cmixlev: %0.3f (%d)\n",
opt->loro_center_mix_level, s->loro_center_mix_level);
av_dlog(avctx, "loro_surmixlev: %0.3f (%d)\n",
opt->loro_surround_mix_level, s->loro_surround_mix_level);
} else {
av_dlog(avctx, "extended bitstream info 1: {not written}\n");
}
if (opt->extended_bsi_2) {
switch (opt->dolby_surround_ex_mode) {
case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
case AC3ENC_OPT_MODE_ON: av_strlcpy(strbuf, "on", 32); break;
case AC3ENC_OPT_MODE_OFF: av_strlcpy(strbuf, "off", 32); break;
default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_surround_ex_mode);
}
av_dlog(avctx, "dsurex_mode: %s\n", strbuf);
switch (opt->dolby_headphone_mode) {
case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
case AC3ENC_OPT_MODE_ON: av_strlcpy(strbuf, "on", 32); break;
case AC3ENC_OPT_MODE_OFF: av_strlcpy(strbuf, "off", 32); break;
default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_headphone_mode);
}
av_dlog(avctx, "dheadphone_mode: %s\n", strbuf);
switch (opt->ad_converter_type) {
case AC3ENC_OPT_ADCONV_STANDARD: av_strlcpy(strbuf, "standard", 32); break;
case AC3ENC_OPT_ADCONV_HDCD: av_strlcpy(strbuf, "hdcd", 32); break;
default: snprintf(strbuf, 32, "ERROR (%d)", opt->ad_converter_type);
}
av_dlog(avctx, "ad_conv_type: %s\n", strbuf);
} else {
av_dlog(avctx, "extended bitstream info 2: {not written}\n");
}
}
#endif
}
#define FLT_OPTION_THRESHOLD 0.01
static int validate_float_option(float v, const float *v_list, int v_list_size)
{
int i;
for (i = 0; i < v_list_size; i++) {
if (v < (v_list[i] + FLT_OPTION_THRESHOLD) &&
v > (v_list[i] - FLT_OPTION_THRESHOLD))
break;
}
if (i == v_list_size)
return -1;
return i;
}
static void validate_mix_level(void *log_ctx, const char *opt_name,
float *opt_param, const float *list,
int list_size, int default_value, int min_value,
int *ctx_param)
{
int mixlev = validate_float_option(*opt_param, list, list_size);
if (mixlev < min_value) {
mixlev = default_value;
if (*opt_param >= 0.0) {
av_log(log_ctx, AV_LOG_WARNING, "requested %s is not valid. using "
"default value: %0.3f\n", opt_name, list[mixlev]);
}
}
*opt_param = list[mixlev];
*ctx_param = mixlev;
}
/**
* Validate metadata options as set by AVOption system.
* These values can optionally be changed per-frame.
*
* @param s AC-3 encoder private context
*/
int ff_ac3_validate_metadata(AC3EncodeContext *s)
{
AVCodecContext *avctx = s->avctx;
AC3EncOptions *opt = &s->options;
opt->audio_production_info = 0;
opt->extended_bsi_1 = 0;
opt->extended_bsi_2 = 0;
opt->eac3_mixing_metadata = 0;
opt->eac3_info_metadata = 0;
/* determine mixing metadata / xbsi1 use */
if (s->channel_mode > AC3_CHMODE_STEREO && opt->preferred_stereo_downmix != AC3ENC_OPT_NONE) {
opt->extended_bsi_1 = 1;
opt->eac3_mixing_metadata = 1;
}
if (s->has_center &&
(opt->ltrt_center_mix_level >= 0 || opt->loro_center_mix_level >= 0)) {
opt->extended_bsi_1 = 1;
opt->eac3_mixing_metadata = 1;
}
if (s->has_surround &&
(opt->ltrt_surround_mix_level >= 0 || opt->loro_surround_mix_level >= 0)) {
opt->extended_bsi_1 = 1;
opt->eac3_mixing_metadata = 1;
}
if (s->eac3) {
/* determine info metadata use */
if (avctx->audio_service_type != AV_AUDIO_SERVICE_TYPE_MAIN)
opt->eac3_info_metadata = 1;
if (opt->copyright != AC3ENC_OPT_NONE || opt->original != AC3ENC_OPT_NONE)
opt->eac3_info_metadata = 1;
if (s->channel_mode == AC3_CHMODE_STEREO &&
(opt->dolby_headphone_mode != AC3ENC_OPT_NONE || opt->dolby_surround_mode != AC3ENC_OPT_NONE))
opt->eac3_info_metadata = 1;
if (s->channel_mode >= AC3_CHMODE_2F2R && opt->dolby_surround_ex_mode != AC3ENC_OPT_NONE)
opt->eac3_info_metadata = 1;
if (opt->mixing_level != AC3ENC_OPT_NONE || opt->room_type != AC3ENC_OPT_NONE ||
opt->ad_converter_type != AC3ENC_OPT_NONE) {
opt->audio_production_info = 1;
opt->eac3_info_metadata = 1;
}
} else {
/* determine audio production info use */
if (opt->mixing_level != AC3ENC_OPT_NONE || opt->room_type != AC3ENC_OPT_NONE)
opt->audio_production_info = 1;
/* determine xbsi2 use */
if (s->channel_mode >= AC3_CHMODE_2F2R && opt->dolby_surround_ex_mode != AC3ENC_OPT_NONE)
opt->extended_bsi_2 = 1;
if (s->channel_mode == AC3_CHMODE_STEREO && opt->dolby_headphone_mode != AC3ENC_OPT_NONE)
opt->extended_bsi_2 = 1;
if (opt->ad_converter_type != AC3ENC_OPT_NONE)
opt->extended_bsi_2 = 1;
}
/* validate AC-3 mixing levels */
if (!s->eac3) {
if (s->has_center) {
validate_mix_level(avctx, "center_mix_level", &opt->center_mix_level,
cmixlev_options, CMIXLEV_NUM_OPTIONS, 1, 0,
&s->center_mix_level);
}
if (s->has_surround) {
validate_mix_level(avctx, "surround_mix_level", &opt->surround_mix_level,
surmixlev_options, SURMIXLEV_NUM_OPTIONS, 1, 0,
&s->surround_mix_level);
}
}
/* validate extended bsi 1 / mixing metadata */
if (opt->extended_bsi_1 || opt->eac3_mixing_metadata) {
/* default preferred stereo downmix */
if (opt->preferred_stereo_downmix == AC3ENC_OPT_NONE)
opt->preferred_stereo_downmix = AC3ENC_OPT_NOT_INDICATED;
if (!s->eac3 || s->has_center) {
/* validate Lt/Rt center mix level */
validate_mix_level(avctx, "ltrt_center_mix_level",
&opt->ltrt_center_mix_level, extmixlev_options,
EXTMIXLEV_NUM_OPTIONS, 5, 0,
&s->ltrt_center_mix_level);
/* validate Lo/Ro center mix level */
validate_mix_level(avctx, "loro_center_mix_level",
&opt->loro_center_mix_level, extmixlev_options,
EXTMIXLEV_NUM_OPTIONS, 5, 0,
&s->loro_center_mix_level);
}
if (!s->eac3 || s->has_surround) {
/* validate Lt/Rt surround mix level */
validate_mix_level(avctx, "ltrt_surround_mix_level",
&opt->ltrt_surround_mix_level, extmixlev_options,
EXTMIXLEV_NUM_OPTIONS, 6, 3,
&s->ltrt_surround_mix_level);
/* validate Lo/Ro surround mix level */
validate_mix_level(avctx, "loro_surround_mix_level",
&opt->loro_surround_mix_level, extmixlev_options,
EXTMIXLEV_NUM_OPTIONS, 6, 3,
&s->loro_surround_mix_level);
}
}
/* validate audio service type / channels combination */
if ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_KARAOKE &&
avctx->channels == 1) ||
((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_COMMENTARY ||
avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_EMERGENCY ||
avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_VOICE_OVER)
&& avctx->channels > 1)) {
av_log(avctx, AV_LOG_ERROR, "invalid audio service type for the "
"specified number of channels\n");
return AVERROR(EINVAL);
}
/* validate extended bsi 2 / info metadata */
if (opt->extended_bsi_2 || opt->eac3_info_metadata) {
/* default dolby headphone mode */
if (opt->dolby_headphone_mode == AC3ENC_OPT_NONE)
opt->dolby_headphone_mode = AC3ENC_OPT_NOT_INDICATED;
/* default dolby surround ex mode */
if (opt->dolby_surround_ex_mode == AC3ENC_OPT_NONE)
opt->dolby_surround_ex_mode = AC3ENC_OPT_NOT_INDICATED;
/* default A/D converter type */
if (opt->ad_converter_type == AC3ENC_OPT_NONE)
opt->ad_converter_type = AC3ENC_OPT_ADCONV_STANDARD;
}
/* copyright & original defaults */
if (!s->eac3 || opt->eac3_info_metadata) {
/* default copyright */
if (opt->copyright == AC3ENC_OPT_NONE)
opt->copyright = AC3ENC_OPT_OFF;
/* default original */
if (opt->original == AC3ENC_OPT_NONE)
opt->original = AC3ENC_OPT_ON;
}
/* dolby surround mode default */
if (!s->eac3 || opt->eac3_info_metadata) {
if (opt->dolby_surround_mode == AC3ENC_OPT_NONE)
opt->dolby_surround_mode = AC3ENC_OPT_NOT_INDICATED;
}
/* validate audio production info */
if (opt->audio_production_info) {
if (opt->mixing_level == AC3ENC_OPT_NONE) {
av_log(avctx, AV_LOG_ERROR, "mixing_level must be set if "
"room_type is set\n");
return AVERROR(EINVAL);
}
if (opt->mixing_level < 80) {
av_log(avctx, AV_LOG_ERROR, "invalid mixing level. must be between "
"80dB and 111dB\n");
return AVERROR(EINVAL);
}
/* default room type */
if (opt->room_type == AC3ENC_OPT_NONE)
opt->room_type = AC3ENC_OPT_NOT_INDICATED;
}
/* set bitstream id for alternate bitstream syntax */
if (!s->eac3 && (opt->extended_bsi_1 || opt->extended_bsi_2)) {
if (s->bitstream_id > 8 && s->bitstream_id < 11) {
static int warn_once = 1;
if (warn_once) {
av_log(avctx, AV_LOG_WARNING, "alternate bitstream syntax is "
"not compatible with reduced samplerates. writing of "
"extended bitstream information will be disabled.\n");
warn_once = 0;
}
} else {
s->bitstream_id = 6;
}
}
return 0;
}
/**
* Finalize encoding and free any memory allocated by the encoder.
*
* @param avctx Codec context
*/
av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
{
int blk, ch;
AC3EncodeContext *s = avctx->priv_data;
av_freep(&s->windowed_samples);
for (ch = 0; ch < s->channels; ch++)
av_freep(&s->planar_samples[ch]);
av_freep(&s->planar_samples);
av_freep(&s->bap_buffer);
av_freep(&s->bap1_buffer);
av_freep(&s->mdct_coef_buffer);
av_freep(&s->fixed_coef_buffer);
av_freep(&s->exp_buffer);
av_freep(&s->grouped_exp_buffer);
av_freep(&s->psd_buffer);
av_freep(&s->band_psd_buffer);
av_freep(&s->mask_buffer);
av_freep(&s->qmant_buffer);
av_freep(&s->cpl_coord_exp_buffer);
av_freep(&s->cpl_coord_mant_buffer);
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
av_freep(&block->mdct_coef);
av_freep(&block->fixed_coef);
av_freep(&block->exp);
av_freep(&block->grouped_exp);
av_freep(&block->psd);
av_freep(&block->band_psd);
av_freep(&block->mask);
av_freep(&block->qmant);
av_freep(&block->cpl_coord_exp);
av_freep(&block->cpl_coord_mant);
}
s->mdct_end(s);
return 0;
}
/*
* Set channel information during initialization.
*/
static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
uint64_t *channel_layout)
{
int ch_layout;
if (channels < 1 || channels > AC3_MAX_CHANNELS)
return AVERROR(EINVAL);
if (*channel_layout > 0x7FF)
return AVERROR(EINVAL);
ch_layout = *channel_layout;
if (!ch_layout)
ch_layout = av_get_default_channel_layout(channels);
s->lfe_on = !!(ch_layout & AV_CH_LOW_FREQUENCY);
s->channels = channels;
s->fbw_channels = channels - s->lfe_on;
s->lfe_channel = s->lfe_on ? s->fbw_channels + 1 : -1;
if (s->lfe_on)
ch_layout -= AV_CH_LOW_FREQUENCY;
switch (ch_layout) {
case AV_CH_LAYOUT_MONO: s->channel_mode = AC3_CHMODE_MONO; break;
case AV_CH_LAYOUT_STEREO: s->channel_mode = AC3_CHMODE_STEREO; break;
case AV_CH_LAYOUT_SURROUND: s->channel_mode = AC3_CHMODE_3F; break;
case AV_CH_LAYOUT_2_1: s->channel_mode = AC3_CHMODE_2F1R; break;
case AV_CH_LAYOUT_4POINT0: s->channel_mode = AC3_CHMODE_3F1R; break;
case AV_CH_LAYOUT_QUAD:
case AV_CH_LAYOUT_2_2: s->channel_mode = AC3_CHMODE_2F2R; break;
case AV_CH_LAYOUT_5POINT0:
case AV_CH_LAYOUT_5POINT0_BACK: s->channel_mode = AC3_CHMODE_3F2R; break;
default:
return AVERROR(EINVAL);
}
s->has_center = (s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO;
s->has_surround = s->channel_mode & 0x04;
s->channel_map = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
*channel_layout = ch_layout;
if (s->lfe_on)
*channel_layout |= AV_CH_LOW_FREQUENCY;
return 0;
}
static av_cold int validate_options(AC3EncodeContext *s)
{
AVCodecContext *avctx = s->avctx;
int i, ret, max_sr;
/* validate channel layout */
if (!avctx->channel_layout) {
av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
"encoder will guess the layout, but it "
"might be incorrect.\n");
}
ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
if (ret) {
av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
return ret;
}
/* validate sample rate */
/* note: max_sr could be changed from 2 to 5 for E-AC-3 once we find a
decoder that supports half sample rate so we can validate that
the generated files are correct. */
max_sr = s->eac3 ? 2 : 8;
for (i = 0; i <= max_sr; i++) {
if ((ff_ac3_sample_rate_tab[i % 3] >> (i / 3)) == avctx->sample_rate)
break;
}
if (i > max_sr) {
av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
return AVERROR(EINVAL);
}
s->sample_rate = avctx->sample_rate;
s->bit_alloc.sr_shift = i / 3;
s->bit_alloc.sr_code = i % 3;
s->bitstream_id = s->eac3 ? 16 : 8 + s->bit_alloc.sr_shift;
/* select a default bit rate if not set by the user */
if (!avctx->bit_rate) {
switch (s->fbw_channels) {
case 1: avctx->bit_rate = 96000; break;
case 2: avctx->bit_rate = 192000; break;
case 3: avctx->bit_rate = 320000; break;
case 4: avctx->bit_rate = 384000; break;
case 5: avctx->bit_rate = 448000; break;
}
}
/* validate bit rate */
if (s->eac3) {
int max_br, min_br, wpf, min_br_dist, min_br_code;
int num_blks_code, num_blocks, frame_samples;
/* calculate min/max bitrate */
/* TODO: More testing with 3 and 2 blocks. All E-AC-3 samples I've
found use either 6 blocks or 1 block, even though 2 or 3 blocks
would work as far as the bit rate is concerned. */
for (num_blks_code = 3; num_blks_code >= 0; num_blks_code--) {
num_blocks = ((int[]){ 1, 2, 3, 6 })[num_blks_code];
frame_samples = AC3_BLOCK_SIZE * num_blocks;
max_br = 2048 * s->sample_rate / frame_samples * 16;
min_br = ((s->sample_rate + (frame_samples-1)) / frame_samples) * 16;
if (avctx->bit_rate <= max_br)
break;
}
if (avctx->bit_rate < min_br || avctx->bit_rate > max_br) {
av_log(avctx, AV_LOG_ERROR, "invalid bit rate. must be %d to %d "
"for this sample rate\n", min_br, max_br);
return AVERROR(EINVAL);
}
s->num_blks_code = num_blks_code;
s->num_blocks = num_blocks;
/* calculate words-per-frame for the selected bitrate */
wpf = (avctx->bit_rate / 16) * frame_samples / s->sample_rate;
av_assert1(wpf > 0 && wpf <= 2048);
/* find the closest AC-3 bitrate code to the selected bitrate.
this is needed for lookup tables for bandwidth and coupling
parameter selection */
min_br_code = -1;
min_br_dist = INT_MAX;
for (i = 0; i < 19; i++) {
int br_dist = abs(ff_ac3_bitrate_tab[i] * 1000 - avctx->bit_rate);
if (br_dist < min_br_dist) {
min_br_dist = br_dist;
min_br_code = i;
}
}
/* make sure the minimum frame size is below the average frame size */
s->frame_size_code = min_br_code << 1;
while (wpf > 1 && wpf * s->sample_rate / AC3_FRAME_SIZE * 16 > avctx->bit_rate)
wpf--;
s->frame_size_min = 2 * wpf;
} else {
int best_br = 0, best_code = 0, best_diff = INT_MAX;
for (i = 0; i < 19; i++) {
int br = (ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift) * 1000;
int diff = abs(br - avctx->bit_rate);
if (diff < best_diff) {
best_br = br;
best_code = i;
best_diff = diff;
}
if (!best_diff)
break;
}
avctx->bit_rate = best_br;
s->frame_size_code = best_code << 1;
s->frame_size_min = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
s->num_blks_code = 0x3;
s->num_blocks = 6;
}
s->bit_rate = avctx->bit_rate;
s->frame_size = s->frame_size_min;
/* validate cutoff */
if (avctx->cutoff < 0) {
av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
return AVERROR(EINVAL);
}
s->cutoff = avctx->cutoff;
if (s->cutoff > (s->sample_rate >> 1))
s->cutoff = s->sample_rate >> 1;
ret = ff_ac3_validate_metadata(s);
if (ret)
return ret;
s->rematrixing_enabled = s->options.stereo_rematrixing &&
(s->channel_mode == AC3_CHMODE_STEREO);
s->cpl_enabled = s->options.channel_coupling &&
s->channel_mode >= AC3_CHMODE_STEREO;
return 0;
}
/*
* Set bandwidth for all channels.
* The user can optionally supply a cutoff frequency. Otherwise an appropriate
* default value will be used.
*/
static av_cold void set_bandwidth(AC3EncodeContext *s)
{
int blk, ch, cpl_start;
if (s->cutoff) {
/* calculate bandwidth based on user-specified cutoff frequency */
int fbw_coeffs;
fbw_coeffs = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
s->bandwidth_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
} else {
/* use default bandwidth setting */
s->bandwidth_code = ac3_bandwidth_tab[s->fbw_channels-1][s->bit_alloc.sr_code][s->frame_size_code/2];
}
/* set number of coefficients for each channel */
for (ch = 1; ch <= s->fbw_channels; ch++) {
s->start_freq[ch] = 0;
for (blk = 0; blk < s->num_blocks; blk++)
s->blocks[blk].end_freq[ch] = s->bandwidth_code * 3 + 73;
}
/* LFE channel always has 7 coefs */
if (s->lfe_on) {
s->start_freq[s->lfe_channel] = 0;
for (blk = 0; blk < s->num_blocks; blk++)
s->blocks[blk].end_freq[ch] = 7;
}
/* initialize coupling strategy */
if (s->cpl_enabled) {
if (s->options.cpl_start != AC3ENC_OPT_AUTO) {
cpl_start = s->options.cpl_start;
} else {
cpl_start = ac3_coupling_start_tab[s->channel_mode-2][s->bit_alloc.sr_code][s->frame_size_code/2];
if (cpl_start < 0) {
if (s->options.channel_coupling == AC3ENC_OPT_AUTO)
s->cpl_enabled = 0;
else
cpl_start = 15;
}
}
}
if (s->cpl_enabled) {
int i, cpl_start_band, cpl_end_band;
uint8_t *cpl_band_sizes = s->cpl_band_sizes;
cpl_end_band = s->bandwidth_code / 4 + 3;
cpl_start_band = av_clip(cpl_start, 0, FFMIN(cpl_end_band-1, 15));
s->num_cpl_subbands = cpl_end_band - cpl_start_band;
s->num_cpl_bands = 1;
*cpl_band_sizes = 12;
for (i = cpl_start_band + 1; i < cpl_end_band; i++) {
if (ff_eac3_default_cpl_band_struct[i]) {
*cpl_band_sizes += 12;
} else {
s->num_cpl_bands++;
cpl_band_sizes++;
*cpl_band_sizes = 12;
}
}
s->start_freq[CPL_CH] = cpl_start_band * 12 + 37;
s->cpl_end_freq = cpl_end_band * 12 + 37;
for (blk = 0; blk < s->num_blocks; blk++)
s->blocks[blk].end_freq[CPL_CH] = s->cpl_end_freq;
}
}
static av_cold int allocate_buffers(AC3EncodeContext *s)
{
AVCodecContext *avctx = s->avctx;
int blk, ch;
int channels = s->channels + 1; /* includes coupling channel */
int channel_blocks = channels * s->num_blocks;
int total_coefs = AC3_MAX_COEFS * channel_blocks;
if (s->allocate_sample_buffers(s))
goto alloc_fail;
FF_ALLOC_OR_GOTO(avctx, s->bap_buffer, total_coefs *
sizeof(*s->bap_buffer), alloc_fail);
FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, total_coefs *
sizeof(*s->bap1_buffer), alloc_fail);
FF_ALLOCZ_OR_GOTO(avctx, s->mdct_coef_buffer, total_coefs *
sizeof(*s->mdct_coef_buffer), alloc_fail);
FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, total_coefs *
sizeof(*s->exp_buffer), alloc_fail);
FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, channel_blocks * 128 *
sizeof(*s->grouped_exp_buffer), alloc_fail);
FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, total_coefs *
sizeof(*s->psd_buffer), alloc_fail);
FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, channel_blocks * 64 *
sizeof(*s->band_psd_buffer), alloc_fail);
FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, channel_blocks * 64 *
sizeof(*s->mask_buffer), alloc_fail);
FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, total_coefs *
sizeof(*s->qmant_buffer), alloc_fail);
if (s->cpl_enabled) {
FF_ALLOC_OR_GOTO(avctx, s->cpl_coord_exp_buffer, channel_blocks * 16 *
sizeof(*s->cpl_coord_exp_buffer), alloc_fail);
FF_ALLOC_OR_GOTO(avctx, s->cpl_coord_mant_buffer, channel_blocks * 16 *
sizeof(*s->cpl_coord_mant_buffer), alloc_fail);
}
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, channels * sizeof(*block->mdct_coef),
alloc_fail);
FF_ALLOCZ_OR_GOTO(avctx, block->exp, channels * sizeof(*block->exp),
alloc_fail);
FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, channels * sizeof(*block->grouped_exp),
alloc_fail);
FF_ALLOCZ_OR_GOTO(avctx, block->psd, channels * sizeof(*block->psd),
alloc_fail);
FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, channels * sizeof(*block->band_psd),
alloc_fail);
FF_ALLOCZ_OR_GOTO(avctx, block->mask, channels * sizeof(*block->mask),
alloc_fail);
FF_ALLOCZ_OR_GOTO(avctx, block->qmant, channels * sizeof(*block->qmant),
alloc_fail);
if (s->cpl_enabled) {
FF_ALLOCZ_OR_GOTO(avctx, block->cpl_coord_exp, channels * sizeof(*block->cpl_coord_exp),
alloc_fail);
FF_ALLOCZ_OR_GOTO(avctx, block->cpl_coord_mant, channels * sizeof(*block->cpl_coord_mant),
alloc_fail);
}
for (ch = 0; ch < channels; ch++) {
/* arrangement: block, channel, coeff */
block->grouped_exp[ch] = &s->grouped_exp_buffer[128 * (blk * channels + ch)];
block->psd[ch] = &s->psd_buffer [AC3_MAX_COEFS * (blk * channels + ch)];
block->band_psd[ch] = &s->band_psd_buffer [64 * (blk * channels + ch)];
block->mask[ch] = &s->mask_buffer [64 * (blk * channels + ch)];
block->qmant[ch] = &s->qmant_buffer [AC3_MAX_COEFS * (blk * channels + ch)];
if (s->cpl_enabled) {
block->cpl_coord_exp[ch] = &s->cpl_coord_exp_buffer [16 * (blk * channels + ch)];
block->cpl_coord_mant[ch] = &s->cpl_coord_mant_buffer[16 * (blk * channels + ch)];
}
/* arrangement: channel, block, coeff */
block->exp[ch] = &s->exp_buffer [AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
block->mdct_coef[ch] = &s->mdct_coef_buffer [AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
}
}
if (!s->fixed_point) {
FF_ALLOCZ_OR_GOTO(avctx, s->fixed_coef_buffer, total_coefs *
sizeof(*s->fixed_coef_buffer), alloc_fail);
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, channels *
sizeof(*block->fixed_coef), alloc_fail);
for (ch = 0; ch < channels; ch++)
block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (s->num_blocks * ch + blk)];
}
} else {
for (blk = 0; blk < s->num_blocks; blk++) {
AC3Block *block = &s->blocks[blk];
FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, channels *
sizeof(*block->fixed_coef), alloc_fail);
for (ch = 0; ch < channels; ch++)
block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
}
}
return 0;
alloc_fail:
return AVERROR(ENOMEM);
}
av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
{
AC3EncodeContext *s = avctx->priv_data;
int ret, frame_size_58;
s->avctx = avctx;
s->eac3 = avctx->codec_id == AV_CODEC_ID_EAC3;
ff_ac3_common_init();
ret = validate_options(s);
if (ret)
return ret;
avctx->frame_size = AC3_BLOCK_SIZE * s->num_blocks;
avctx->initial_padding = AC3_BLOCK_SIZE;
s->bitstream_mode = avctx->audio_service_type;
if (s->bitstream_mode == AV_AUDIO_SERVICE_TYPE_KARAOKE)
s->bitstream_mode = 0x7;
s->bits_written = 0;
s->samples_written = 0;
/* calculate crc_inv for both possible frame sizes */
frame_size_58 = (( s->frame_size >> 2) + ( s->frame_size >> 4)) << 1;
s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
if (s->bit_alloc.sr_code == 1) {
frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
}
/* set function pointers */
if (CONFIG_AC3_FIXED_ENCODER && s->fixed_point) {
s->mdct_end = ff_ac3_fixed_mdct_end;
s->mdct_init = ff_ac3_fixed_mdct_init;
s->allocate_sample_buffers = ff_ac3_fixed_allocate_sample_buffers;
} else if (CONFIG_AC3_ENCODER || CONFIG_EAC3_ENCODER) {
s->mdct_end = ff_ac3_float_mdct_end;
s->mdct_init = ff_ac3_float_mdct_init;
s->allocate_sample_buffers = ff_ac3_float_allocate_sample_buffers;
}
if (CONFIG_EAC3_ENCODER && s->eac3)
s->output_frame_header = ff_eac3_output_frame_header;
else
s->output_frame_header = ac3_output_frame_header;
set_bandwidth(s);
exponent_init(s);
bit_alloc_init(s);
ret = s->mdct_init(s);
if (ret)
goto init_fail;
ret = allocate_buffers(s);
if (ret)
goto init_fail;
ff_audiodsp_init(&s->adsp);
ff_me_cmp_init(&s->mecc, avctx);
ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
dprint_options(s);
return 0;
init_fail:
ff_ac3_encode_close(avctx);
return ret;
}
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