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FFmpeg/libavcodec/flacenc.c

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/*
* FLAC audio encoder
* Copyright (c) 2006 Justin Ruggles <justin.ruggles@gmail.com>
*
* This file is part of FFmpeg.
*
* FFmpeg 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,
* 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
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/avassert.h"
#include "libavutil/crc.h"
#include "libavutil/intmath.h"
#include "libavutil/md5.h"
#include "libavutil/opt.h"
#include "avcodec.h"
#include "dsputil.h"
#include "get_bits.h"
#include "golomb.h"
#include "internal.h"
#include "lpc.h"
#include "flac.h"
#include "flacdata.h"
#include "flacdsp.h"
#define FLAC_SUBFRAME_CONSTANT 0
#define FLAC_SUBFRAME_VERBATIM 1
#define FLAC_SUBFRAME_FIXED 8
#define FLAC_SUBFRAME_LPC 32
#define MAX_FIXED_ORDER 4
#define MAX_PARTITION_ORDER 8
#define MAX_PARTITIONS (1 << MAX_PARTITION_ORDER)
#define MAX_LPC_PRECISION 15
#define MAX_LPC_SHIFT 15
enum CodingMode {
CODING_MODE_RICE = 4,
CODING_MODE_RICE2 = 5,
};
typedef struct CompressionOptions {
int compression_level;
int block_time_ms;
enum FFLPCType lpc_type;
int lpc_passes;
int lpc_coeff_precision;
int min_prediction_order;
int max_prediction_order;
int prediction_order_method;
int min_partition_order;
int max_partition_order;
int ch_mode;
} CompressionOptions;
typedef struct RiceContext {
enum CodingMode coding_mode;
int porder;
int params[MAX_PARTITIONS];
} RiceContext;
typedef struct FlacSubframe {
int type;
int type_code;
int obits;
int wasted;
int order;
int32_t coefs[MAX_LPC_ORDER];
int shift;
RiceContext rc;
int32_t samples[FLAC_MAX_BLOCKSIZE];
int32_t residual[FLAC_MAX_BLOCKSIZE+1];
} FlacSubframe;
typedef struct FlacFrame {
FlacSubframe subframes[FLAC_MAX_CHANNELS];
int blocksize;
int bs_code[2];
uint8_t crc8;
int ch_mode;
int verbatim_only;
} FlacFrame;
typedef struct FlacEncodeContext {
AVClass *class;
PutBitContext pb;
int channels;
int samplerate;
int sr_code[2];
int bps_code;
int max_blocksize;
int min_framesize;
int max_framesize;
int max_encoded_framesize;
uint32_t frame_count;
uint64_t sample_count;
uint8_t md5sum[16];
FlacFrame frame;
CompressionOptions options;
AVCodecContext *avctx;
LPCContext lpc_ctx;
struct AVMD5 *md5ctx;
uint8_t *md5_buffer;
unsigned int md5_buffer_size;
DSPContext dsp;
FLACDSPContext flac_dsp;
} FlacEncodeContext;
/**
* Write streaminfo metadata block to byte array.
*/
static void write_streaminfo(FlacEncodeContext *s, uint8_t *header)
{
PutBitContext pb;
memset(header, 0, FLAC_STREAMINFO_SIZE);
init_put_bits(&pb, header, FLAC_STREAMINFO_SIZE);
/* streaminfo metadata block */
put_bits(&pb, 16, s->max_blocksize);
put_bits(&pb, 16, s->max_blocksize);
put_bits(&pb, 24, s->min_framesize);
put_bits(&pb, 24, s->max_framesize);
put_bits(&pb, 20, s->samplerate);
put_bits(&pb, 3, s->channels-1);
put_bits(&pb, 5, s->avctx->bits_per_raw_sample - 1);
/* write 36-bit sample count in 2 put_bits() calls */
put_bits(&pb, 24, (s->sample_count & 0xFFFFFF000LL) >> 12);
put_bits(&pb, 12, s->sample_count & 0x000000FFFLL);
flush_put_bits(&pb);
memcpy(&header[18], s->md5sum, 16);
}
/**
* Set blocksize based on samplerate.
* Choose the closest predefined blocksize >= BLOCK_TIME_MS milliseconds.
*/
static int select_blocksize(int samplerate, int block_time_ms)
{
int i;
int target;
int blocksize;
av_assert0(samplerate > 0);
blocksize = ff_flac_blocksize_table[1];
target = (samplerate * block_time_ms) / 1000;
for (i = 0; i < 16; i++) {
if (target >= ff_flac_blocksize_table[i] &&
ff_flac_blocksize_table[i] > blocksize) {
blocksize = ff_flac_blocksize_table[i];
}
}
return blocksize;
}
static av_cold void dprint_compression_options(FlacEncodeContext *s)
{
AVCodecContext *avctx = s->avctx;
CompressionOptions *opt = &s->options;
av_log(avctx, AV_LOG_DEBUG, " compression: %d\n", opt->compression_level);
switch (opt->lpc_type) {
case FF_LPC_TYPE_NONE:
av_log(avctx, AV_LOG_DEBUG, " lpc type: None\n");
break;
case FF_LPC_TYPE_FIXED:
av_log(avctx, AV_LOG_DEBUG, " lpc type: Fixed pre-defined coefficients\n");
break;
case FF_LPC_TYPE_LEVINSON:
av_log(avctx, AV_LOG_DEBUG, " lpc type: Levinson-Durbin recursion with Welch window\n");
break;
case FF_LPC_TYPE_CHOLESKY:
av_log(avctx, AV_LOG_DEBUG, " lpc type: Cholesky factorization, %d pass%s\n",
opt->lpc_passes, opt->lpc_passes == 1 ? "" : "es");
break;
}
av_log(avctx, AV_LOG_DEBUG, " prediction order: %d, %d\n",
opt->min_prediction_order, opt->max_prediction_order);
switch (opt->prediction_order_method) {
case ORDER_METHOD_EST:
av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "estimate");
break;
case ORDER_METHOD_2LEVEL:
av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "2-level");
break;
case ORDER_METHOD_4LEVEL:
av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "4-level");
break;
case ORDER_METHOD_8LEVEL:
av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "8-level");
break;
case ORDER_METHOD_SEARCH:
av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "full search");
break;
case ORDER_METHOD_LOG:
av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "log search");
break;
}
av_log(avctx, AV_LOG_DEBUG, " partition order: %d, %d\n",
opt->min_partition_order, opt->max_partition_order);
av_log(avctx, AV_LOG_DEBUG, " block size: %d\n", avctx->frame_size);
av_log(avctx, AV_LOG_DEBUG, " lpc precision: %d\n",
opt->lpc_coeff_precision);
}
static av_cold int flac_encode_init(AVCodecContext *avctx)
{
int freq = avctx->sample_rate;
int channels = avctx->channels;
FlacEncodeContext *s = avctx->priv_data;
int i, level, ret;
uint8_t *streaminfo;
s->avctx = avctx;
switch (avctx->sample_fmt) {
case AV_SAMPLE_FMT_S16:
avctx->bits_per_raw_sample = 16;
s->bps_code = 4;
break;
case AV_SAMPLE_FMT_S32:
if (avctx->bits_per_raw_sample != 24)
av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");
avctx->bits_per_raw_sample = 24;
s->bps_code = 6;
break;
}
if (channels < 1 || channels > FLAC_MAX_CHANNELS)
return -1;
s->channels = channels;
/* find samplerate in table */
if (freq < 1)
return -1;
for (i = 4; i < 12; i++) {
if (freq == ff_flac_sample_rate_table[i]) {
s->samplerate = ff_flac_sample_rate_table[i];
s->sr_code[0] = i;
s->sr_code[1] = 0;
break;
}
}
/* if not in table, samplerate is non-standard */
if (i == 12) {
if (freq % 1000 == 0 && freq < 255000) {
s->sr_code[0] = 12;
s->sr_code[1] = freq / 1000;
} else if (freq % 10 == 0 && freq < 655350) {
s->sr_code[0] = 14;
s->sr_code[1] = freq / 10;
} else if (freq < 65535) {
s->sr_code[0] = 13;
s->sr_code[1] = freq;
} else {
return -1;
}
s->samplerate = freq;
}
/* set compression option defaults based on avctx->compression_level */
if (avctx->compression_level < 0)
s->options.compression_level = 5;
else
s->options.compression_level = avctx->compression_level;
level = s->options.compression_level;
if (level > 12) {
av_log(avctx, AV_LOG_ERROR, "invalid compression level: %d\n",
s->options.compression_level);
return -1;
}
s->options.block_time_ms = ((int[]){ 27, 27, 27,105,105,105,105,105,105,105,105,105,105})[level];
if (s->options.lpc_type == FF_LPC_TYPE_DEFAULT)
s->options.lpc_type = ((int[]){ FF_LPC_TYPE_FIXED, FF_LPC_TYPE_FIXED, FF_LPC_TYPE_FIXED,
FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON,
FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON,
FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON, FF_LPC_TYPE_LEVINSON,
FF_LPC_TYPE_LEVINSON})[level];
s->options.min_prediction_order = ((int[]){ 2, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1})[level];
s->options.max_prediction_order = ((int[]){ 3, 4, 4, 6, 8, 8, 8, 8, 12, 12, 12, 32, 32})[level];
if (s->options.prediction_order_method < 0)
s->options.prediction_order_method = ((int[]){ ORDER_METHOD_EST, ORDER_METHOD_EST, ORDER_METHOD_EST,
ORDER_METHOD_EST, ORDER_METHOD_EST, ORDER_METHOD_EST,
ORDER_METHOD_4LEVEL, ORDER_METHOD_LOG, ORDER_METHOD_4LEVEL,
ORDER_METHOD_LOG, ORDER_METHOD_SEARCH, ORDER_METHOD_LOG,
ORDER_METHOD_SEARCH})[level];
if (s->options.min_partition_order > s->options.max_partition_order) {
av_log(avctx, AV_LOG_ERROR, "invalid partition orders: min=%d max=%d\n",
s->options.min_partition_order, s->options.max_partition_order);
return AVERROR(EINVAL);
}
if (s->options.min_partition_order < 0)
s->options.min_partition_order = ((int[]){ 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})[level];
if (s->options.max_partition_order < 0)
s->options.max_partition_order = ((int[]){ 2, 2, 3, 3, 3, 8, 8, 8, 8, 8, 8, 8, 8})[level];
if (s->options.lpc_type == FF_LPC_TYPE_NONE) {
s->options.min_prediction_order = 0;
} else if (avctx->min_prediction_order >= 0) {
if (s->options.lpc_type == FF_LPC_TYPE_FIXED) {
if (avctx->min_prediction_order > MAX_FIXED_ORDER) {
av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n",
avctx->min_prediction_order);
return -1;
}
} else if (avctx->min_prediction_order < MIN_LPC_ORDER ||
avctx->min_prediction_order > MAX_LPC_ORDER) {
av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n",
avctx->min_prediction_order);
return -1;
}
s->options.min_prediction_order = avctx->min_prediction_order;
}
if (s->options.lpc_type == FF_LPC_TYPE_NONE) {
s->options.max_prediction_order = 0;
} else if (avctx->max_prediction_order >= 0) {
if (s->options.lpc_type == FF_LPC_TYPE_FIXED) {
if (avctx->max_prediction_order > MAX_FIXED_ORDER) {
av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n",
avctx->max_prediction_order);
return -1;
}
} else if (avctx->max_prediction_order < MIN_LPC_ORDER ||
avctx->max_prediction_order > MAX_LPC_ORDER) {
av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n",
avctx->max_prediction_order);
return -1;
}
s->options.max_prediction_order = avctx->max_prediction_order;
}
if (s->options.max_prediction_order < s->options.min_prediction_order) {
av_log(avctx, AV_LOG_ERROR, "invalid prediction orders: min=%d max=%d\n",
s->options.min_prediction_order, s->options.max_prediction_order);
return -1;
}
if (avctx->frame_size > 0) {
if (avctx->frame_size < FLAC_MIN_BLOCKSIZE ||
avctx->frame_size > FLAC_MAX_BLOCKSIZE) {
av_log(avctx, AV_LOG_ERROR, "invalid block size: %d\n",
avctx->frame_size);
return -1;
}
} else {
s->avctx->frame_size = select_blocksize(s->samplerate, s->options.block_time_ms);
}
s->max_blocksize = s->avctx->frame_size;
/* set maximum encoded frame size in verbatim mode */
s->max_framesize = ff_flac_get_max_frame_size(s->avctx->frame_size,
s->channels,
s->avctx->bits_per_raw_sample);
/* initialize MD5 context */
s->md5ctx = av_md5_alloc();
if (!s->md5ctx)
return AVERROR(ENOMEM);
av_md5_init(s->md5ctx);
streaminfo = av_malloc(FLAC_STREAMINFO_SIZE);
if (!streaminfo)
return AVERROR(ENOMEM);
write_streaminfo(s, streaminfo);
avctx->extradata = streaminfo;
avctx->extradata_size = FLAC_STREAMINFO_SIZE;
s->frame_count = 0;
s->min_framesize = s->max_framesize;
#if FF_API_OLD_ENCODE_AUDIO
avctx->coded_frame = avcodec_alloc_frame();
if (!avctx->coded_frame)
return AVERROR(ENOMEM);
#endif
if (channels == 3 &&
avctx->channel_layout != (AV_CH_LAYOUT_STEREO|AV_CH_FRONT_CENTER) ||
channels == 4 &&
avctx->channel_layout != AV_CH_LAYOUT_2_2 &&
avctx->channel_layout != AV_CH_LAYOUT_QUAD ||
channels == 5 &&
avctx->channel_layout != AV_CH_LAYOUT_5POINT0 &&
avctx->channel_layout != AV_CH_LAYOUT_5POINT0_BACK ||
channels == 6 &&
avctx->channel_layout != AV_CH_LAYOUT_5POINT1 &&
avctx->channel_layout != AV_CH_LAYOUT_5POINT1_BACK) {
if (avctx->channel_layout) {
av_log(avctx, AV_LOG_ERROR, "Channel layout not supported by Flac, "
"output stream will have incorrect "
"channel layout.\n");
} else {
av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The encoder "
"will use Flac channel layout for "
"%d channels.\n", channels);
}
}
ret = ff_lpc_init(&s->lpc_ctx, avctx->frame_size,
s->options.max_prediction_order, FF_LPC_TYPE_LEVINSON);
ff_dsputil_init(&s->dsp, avctx);
ff_flacdsp_init(&s->flac_dsp, avctx->sample_fmt,
avctx->bits_per_raw_sample);
dprint_compression_options(s);
return ret;
}
static void init_frame(FlacEncodeContext *s, int nb_samples)
{
int i, ch;
FlacFrame *frame;
frame = &s->frame;
for (i = 0; i < 16; i++) {
if (nb_samples == ff_flac_blocksize_table[i]) {
frame->blocksize = ff_flac_blocksize_table[i];
frame->bs_code[0] = i;
frame->bs_code[1] = 0;
break;
}
}
if (i == 16) {
frame->blocksize = nb_samples;
if (frame->blocksize <= 256) {
frame->bs_code[0] = 6;
frame->bs_code[1] = frame->blocksize-1;
} else {
frame->bs_code[0] = 7;
frame->bs_code[1] = frame->blocksize-1;
}
}
for (ch = 0; ch < s->channels; ch++) {
FlacSubframe *sub = &frame->subframes[ch];
sub->wasted = 0;
sub->obits = s->avctx->bits_per_raw_sample;
if (sub->obits > 16)
sub->rc.coding_mode = CODING_MODE_RICE2;
else
sub->rc.coding_mode = CODING_MODE_RICE;
}
frame->verbatim_only = 0;
}
/**
* Copy channel-interleaved input samples into separate subframes.
*/
static void copy_samples(FlacEncodeContext *s, const void *samples)
{
int i, j, ch;
FlacFrame *frame;
int shift = av_get_bytes_per_sample(s->avctx->sample_fmt) * 8 -
s->avctx->bits_per_raw_sample;
#define COPY_SAMPLES(bits) do { \
const int ## bits ## _t *samples0 = samples; \
frame = &s->frame; \
for (i = 0, j = 0; i < frame->blocksize; i++) \
for (ch = 0; ch < s->channels; ch++, j++) \
frame->subframes[ch].samples[i] = samples0[j] >> shift; \
} while (0)
if (s->avctx->sample_fmt == AV_SAMPLE_FMT_S16)
COPY_SAMPLES(16);
else
COPY_SAMPLES(32);
}
static uint64_t rice_count_exact(int32_t *res, int n, int k)
{
int i;
uint64_t count = 0;
for (i = 0; i < n; i++) {
int32_t v = -2 * res[i] - 1;
v ^= v >> 31;
count += (v >> k) + 1 + k;
}
return count;
}
static uint64_t subframe_count_exact(FlacEncodeContext *s, FlacSubframe *sub,
int pred_order)
{
int p, porder, psize;
int i, part_end;
uint64_t count = 0;
/* subframe header */
count += 8;
/* subframe */
if (sub->type == FLAC_SUBFRAME_CONSTANT) {
count += sub->obits;
} else if (sub->type == FLAC_SUBFRAME_VERBATIM) {
count += s->frame.blocksize * sub->obits;
} else {
/* warm-up samples */
count += pred_order * sub->obits;
/* LPC coefficients */
if (sub->type == FLAC_SUBFRAME_LPC)
count += 4 + 5 + pred_order * s->options.lpc_coeff_precision;
/* rice-encoded block */
count += 2;
/* partition order */
porder = sub->rc.porder;
psize = s->frame.blocksize >> porder;
count += 4;
/* residual */
i = pred_order;
part_end = psize;
for (p = 0; p < 1 << porder; p++) {
int k = sub->rc.params[p];
count += sub->rc.coding_mode;
count += rice_count_exact(&sub->residual[i], part_end - i, k);
i = part_end;
part_end = FFMIN(s->frame.blocksize, part_end + psize);
}
}
return count;
}
#define rice_encode_count(sum, n, k) (((n)*((k)+1))+((sum-(n>>1))>>(k)))
/**
* Solve for d/dk(rice_encode_count) = n-((sum-(n>>1))>>(k+1)) = 0.
*/
static int find_optimal_param(uint64_t sum, int n, int max_param)
{
int k;
uint64_t sum2;
if (sum <= n >> 1)
return 0;
sum2 = sum - (n >> 1);
k = av_log2(av_clipl_int32(sum2 / n));
return FFMIN(k, max_param);
}
static uint64_t calc_optimal_rice_params(RiceContext *rc, int porder,
uint64_t *sums, int n, int pred_order)
{
int i;
int k, cnt, part, max_param;
uint64_t all_bits;
max_param = (1 << rc->coding_mode) - 2;
part = (1 << porder);
all_bits = 4 * part;
cnt = (n >> porder) - pred_order;
for (i = 0; i < part; i++) {
k = find_optimal_param(sums[i], cnt, max_param);
rc->params[i] = k;
all_bits += rice_encode_count(sums[i], cnt, k);
cnt = n >> porder;
}
rc->porder = porder;
return all_bits;
}
static void calc_sums(int pmin, int pmax, uint32_t *data, int n, int pred_order,
uint64_t sums[][MAX_PARTITIONS])
{
int i, j;
int parts;
uint32_t *res, *res_end;
/* sums for highest level */
parts = (1 << pmax);
res = &data[pred_order];
res_end = &data[n >> pmax];
for (i = 0; i < parts; i++) {
uint64_t sum = 0;
while (res < res_end)
sum += *(res++);
sums[pmax][i] = sum;
res_end += n >> pmax;
}
/* sums for lower levels */
for (i = pmax - 1; i >= pmin; i--) {
parts = (1 << i);
for (j = 0; j < parts; j++)
sums[i][j] = sums[i+1][2*j] + sums[i+1][2*j+1];
}
}
static uint64_t calc_rice_params(RiceContext *rc, int pmin, int pmax,
int32_t *data, int n, int pred_order)
{
int i;
uint64_t bits[MAX_PARTITION_ORDER+1];
int opt_porder;
RiceContext tmp_rc;
uint32_t *udata;
uint64_t sums[MAX_PARTITION_ORDER+1][MAX_PARTITIONS];
av_assert1(pmin >= 0 && pmin <= MAX_PARTITION_ORDER);
av_assert1(pmax >= 0 && pmax <= MAX_PARTITION_ORDER);
av_assert1(pmin <= pmax);
tmp_rc.coding_mode = rc->coding_mode;
udata = av_malloc(n * sizeof(uint32_t));
for (i = 0; i < n; i++)
udata[i] = (2*data[i]) ^ (data[i]>>31);
calc_sums(pmin, pmax, udata, n, pred_order, sums);
opt_porder = pmin;
bits[pmin] = UINT32_MAX;
for (i = pmin; i <= pmax; i++) {
bits[i] = calc_optimal_rice_params(&tmp_rc, i, sums[i], n, pred_order);
if (bits[i] <= bits[opt_porder]) {
opt_porder = i;
*rc = tmp_rc;
}
}
av_freep(&udata);
return bits[opt_porder];
}
static int get_max_p_order(int max_porder, int n, int order)
{
int porder = FFMIN(max_porder, av_log2(n^(n-1)));
if (order > 0)
porder = FFMIN(porder, av_log2(n/order));
return porder;
}
static uint64_t find_subframe_rice_params(FlacEncodeContext *s,
FlacSubframe *sub, int pred_order)
{
int pmin = get_max_p_order(s->options.min_partition_order,
s->frame.blocksize, pred_order);
int pmax = get_max_p_order(s->options.max_partition_order,
s->frame.blocksize, pred_order);
uint64_t bits = 8 + pred_order * sub->obits + 2 + sub->rc.coding_mode;
if (sub->type == FLAC_SUBFRAME_LPC)
bits += 4 + 5 + pred_order * s->options.lpc_coeff_precision;
bits += calc_rice_params(&sub->rc, pmin, pmax, sub->residual,
s->frame.blocksize, pred_order);
return bits;
}
static void encode_residual_fixed(int32_t *res, const int32_t *smp, int n,
int order)
{
int i;
for (i = 0; i < order; i++)
res[i] = smp[i];
if (order == 0) {
for (i = order; i < n; i++)
res[i] = smp[i];
} else if (order == 1) {
for (i = order; i < n; i++)
res[i] = smp[i] - smp[i-1];
} else if (order == 2) {
int a = smp[order-1] - smp[order-2];
for (i = order; i < n; i += 2) {
int b = smp[i ] - smp[i-1];
res[i] = b - a;
a = smp[i+1] - smp[i ];
res[i+1] = a - b;
}
} else if (order == 3) {
int a = smp[order-1] - smp[order-2];
int c = smp[order-1] - 2*smp[order-2] + smp[order-3];
for (i = order; i < n; i += 2) {
int b = smp[i ] - smp[i-1];
int d = b - a;
res[i] = d - c;
a = smp[i+1] - smp[i ];
c = a - b;
res[i+1] = c - d;
}
} else {
int a = smp[order-1] - smp[order-2];
int c = smp[order-1] - 2*smp[order-2] + smp[order-3];
int e = smp[order-1] - 3*smp[order-2] + 3*smp[order-3] - smp[order-4];
for (i = order; i < n; i += 2) {
int b = smp[i ] - smp[i-1];
int d = b - a;
int f = d - c;
res[i ] = f - e;
a = smp[i+1] - smp[i ];
c = a - b;
e = c - d;
res[i+1] = e - f;
}
}
}
static int encode_residual_ch(FlacEncodeContext *s, int ch)
{
int i, n;
int min_order, max_order, opt_order, omethod;
FlacFrame *frame;
FlacSubframe *sub;
int32_t coefs[MAX_LPC_ORDER][MAX_LPC_ORDER];
int shift[MAX_LPC_ORDER];
int32_t *res, *smp;
frame = &s->frame;
sub = &frame->subframes[ch];
res = sub->residual;
smp = sub->samples;
n = frame->blocksize;
/* CONSTANT */
for (i = 1; i < n; i++)
if(smp[i] != smp[0])
break;
if (i == n) {
sub->type = sub->type_code = FLAC_SUBFRAME_CONSTANT;
res[0] = smp[0];
return subframe_count_exact(s, sub, 0);
}
/* VERBATIM */
if (frame->verbatim_only || n < 5) {
sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;
memcpy(res, smp, n * sizeof(int32_t));
return subframe_count_exact(s, sub, 0);
}
min_order = s->options.min_prediction_order;
max_order = s->options.max_prediction_order;
omethod = s->options.prediction_order_method;
/* FIXED */
sub->type = FLAC_SUBFRAME_FIXED;
if (s->options.lpc_type == FF_LPC_TYPE_NONE ||
s->options.lpc_type == FF_LPC_TYPE_FIXED || n <= max_order) {
uint64_t bits[MAX_FIXED_ORDER+1];
if (max_order > MAX_FIXED_ORDER)
max_order = MAX_FIXED_ORDER;
opt_order = 0;
bits[0] = UINT32_MAX;
for (i = min_order; i <= max_order; i++) {
encode_residual_fixed(res, smp, n, i);
bits[i] = find_subframe_rice_params(s, sub, i);
if (bits[i] < bits[opt_order])
opt_order = i;
}
sub->order = opt_order;
sub->type_code = sub->type | sub->order;
if (sub->order != max_order) {
encode_residual_fixed(res, smp, n, sub->order);
find_subframe_rice_params(s, sub, sub->order);
}
return subframe_count_exact(s, sub, sub->order);
}
/* LPC */
sub->type = FLAC_SUBFRAME_LPC;
opt_order = ff_lpc_calc_coefs(&s->lpc_ctx, smp, n, min_order, max_order,
s->options.lpc_coeff_precision, coefs, shift, s->options.lpc_type,
s->options.lpc_passes, omethod,
MAX_LPC_SHIFT, 0);
if (omethod == ORDER_METHOD_2LEVEL ||
omethod == ORDER_METHOD_4LEVEL ||
omethod == ORDER_METHOD_8LEVEL) {
int levels = 1 << omethod;
uint64_t bits[1 << ORDER_METHOD_8LEVEL];
int order = -1;
int opt_index = levels-1;
opt_order = max_order-1;
bits[opt_index] = UINT32_MAX;
for (i = levels-1; i >= 0; i--) {
int last_order = order;
order = min_order + (((max_order-min_order+1) * (i+1)) / levels)-1;
order = av_clip(order, min_order - 1, max_order - 1);
if (order == last_order)
continue;
s->flac_dsp.lpc_encode(res, smp, n, order+1, coefs[order],
shift[order]);
bits[i] = find_subframe_rice_params(s, sub, order+1);
if (bits[i] < bits[opt_index]) {
opt_index = i;
opt_order = order;
}
}
opt_order++;
} else if (omethod == ORDER_METHOD_SEARCH) {
// brute-force optimal order search
uint64_t bits[MAX_LPC_ORDER];
opt_order = 0;
bits[0] = UINT32_MAX;
for (i = min_order-1; i < max_order; i++) {
s->flac_dsp.lpc_encode(res, smp, n, i+1, coefs[i], shift[i]);
bits[i] = find_subframe_rice_params(s, sub, i+1);
if (bits[i] < bits[opt_order])
opt_order = i;
}
opt_order++;
} else if (omethod == ORDER_METHOD_LOG) {
uint64_t bits[MAX_LPC_ORDER];
int step;
opt_order = min_order - 1 + (max_order-min_order)/3;
memset(bits, -1, sizeof(bits));
for (step = 16; step; step >>= 1) {
int last = opt_order;
for (i = last-step; i <= last+step; i += step) {
if (i < min_order-1 || i >= max_order || bits[i] < UINT32_MAX)
continue;
s->flac_dsp.lpc_encode(res, smp, n, i+1, coefs[i], shift[i]);
bits[i] = find_subframe_rice_params(s, sub, i+1);
if (bits[i] < bits[opt_order])
opt_order = i;
}
}
opt_order++;
}
sub->order = opt_order;
sub->type_code = sub->type | (sub->order-1);
sub->shift = shift[sub->order-1];
for (i = 0; i < sub->order; i++)
sub->coefs[i] = coefs[sub->order-1][i];
s->flac_dsp.lpc_encode(res, smp, n, sub->order, sub->coefs, sub->shift);
find_subframe_rice_params(s, sub, sub->order);
return subframe_count_exact(s, sub, sub->order);
}
static int count_frame_header(FlacEncodeContext *s)
{
uint8_t av_unused tmp;
int count;
/*
<14> Sync code
<1> Reserved
<1> Blocking strategy
<4> Block size in inter-channel samples
<4> Sample rate
<4> Channel assignment
<3> Sample size in bits
<1> Reserved
*/
count = 32;
/* coded frame number */
PUT_UTF8(s->frame_count, tmp, count += 8;)
/* explicit block size */
if (s->frame.bs_code[0] == 6)
count += 8;
else if (s->frame.bs_code[0] == 7)
count += 16;
/* explicit sample rate */
count += ((s->sr_code[0] == 12) + (s->sr_code[0] > 12)) * 8;
/* frame header CRC-8 */
count += 8;
return count;
}
static int encode_frame(FlacEncodeContext *s)
{
int ch;
uint64_t count;
count = count_frame_header(s);
for (ch = 0; ch < s->channels; ch++)
count += encode_residual_ch(s, ch);
count += (8 - (count & 7)) & 7; // byte alignment
count += 16; // CRC-16
count >>= 3;
if (count > INT_MAX)
return AVERROR_BUG;
return count;
}
static void remove_wasted_bits(FlacEncodeContext *s)
{
int ch, i;
for (ch = 0; ch < s->channels; ch++) {
FlacSubframe *sub = &s->frame.subframes[ch];
int32_t v = 0;
for (i = 0; i < s->frame.blocksize; i++) {
v |= sub->samples[i];
if (v & 1)
break;
}
if (v && !(v & 1)) {
v = av_ctz(v);
for (i = 0; i < s->frame.blocksize; i++)
sub->samples[i] >>= v;
sub->wasted = v;
sub->obits -= v;
/* for 24-bit, check if removing wasted bits makes the range better
suited for using RICE instead of RICE2 for entropy coding */
if (sub->obits <= 17)
sub->rc.coding_mode = CODING_MODE_RICE;
}
}
}
static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n,
int max_rice_param)
{
int i, best;
int32_t lt, rt;
uint64_t sum[4];
uint64_t score[4];
int k;
/* calculate sum of 2nd order residual for each channel */
sum[0] = sum[1] = sum[2] = sum[3] = 0;
for (i = 2; i < n; i++) {
lt = left_ch[i] - 2*left_ch[i-1] + left_ch[i-2];
rt = right_ch[i] - 2*right_ch[i-1] + right_ch[i-2];
sum[2] += FFABS((lt + rt) >> 1);
sum[3] += FFABS(lt - rt);
sum[0] += FFABS(lt);
sum[1] += FFABS(rt);
}
/* estimate bit counts */
for (i = 0; i < 4; i++) {
k = find_optimal_param(2 * sum[i], n, max_rice_param);
sum[i] = rice_encode_count( 2 * sum[i], n, k);
}
/* calculate score for each mode */
score[0] = sum[0] + sum[1];
score[1] = sum[0] + sum[3];
score[2] = sum[1] + sum[3];
score[3] = sum[2] + sum[3];
/* return mode with lowest score */
best = 0;
for (i = 1; i < 4; i++)
if (score[i] < score[best])
best = i;
return best;
}
/**
* Perform stereo channel decorrelation.
*/
static void channel_decorrelation(FlacEncodeContext *s)
{
FlacFrame *frame;
int32_t *left, *right;
int i, n;
frame = &s->frame;
n = frame->blocksize;
left = frame->subframes[0].samples;
right = frame->subframes[1].samples;
if (s->channels != 2) {
frame->ch_mode = FLAC_CHMODE_INDEPENDENT;
return;
}
if (s->options.ch_mode < 0) {
int max_rice_param = (1 << frame->subframes[0].rc.coding_mode) - 2;
frame->ch_mode = estimate_stereo_mode(left, right, n, max_rice_param);
} else
frame->ch_mode = s->options.ch_mode;
/* perform decorrelation and adjust bits-per-sample */
if (frame->ch_mode == FLAC_CHMODE_INDEPENDENT)
return;
if (frame->ch_mode == FLAC_CHMODE_MID_SIDE) {
int32_t tmp;
for (i = 0; i < n; i++) {
tmp = left[i];
left[i] = (tmp + right[i]) >> 1;
right[i] = tmp - right[i];
}
frame->subframes[1].obits++;
} else if (frame->ch_mode == FLAC_CHMODE_LEFT_SIDE) {
for (i = 0; i < n; i++)
right[i] = left[i] - right[i];
frame->subframes[1].obits++;
} else {
for (i = 0; i < n; i++)
left[i] -= right[i];
frame->subframes[0].obits++;
}
}
static void write_utf8(PutBitContext *pb, uint32_t val)
{
uint8_t tmp;
PUT_UTF8(val, tmp, put_bits(pb, 8, tmp);)
}
static void write_frame_header(FlacEncodeContext *s)
{
FlacFrame *frame;
int crc;
frame = &s->frame;
put_bits(&s->pb, 16, 0xFFF8);
put_bits(&s->pb, 4, frame->bs_code[0]);
put_bits(&s->pb, 4, s->sr_code[0]);
if (frame->ch_mode == FLAC_CHMODE_INDEPENDENT)
put_bits(&s->pb, 4, s->channels-1);
else
put_bits(&s->pb, 4, frame->ch_mode + FLAC_MAX_CHANNELS - 1);
put_bits(&s->pb, 3, s->bps_code);
put_bits(&s->pb, 1, 0);
write_utf8(&s->pb, s->frame_count);
if (frame->bs_code[0] == 6)
put_bits(&s->pb, 8, frame->bs_code[1]);
else if (frame->bs_code[0] == 7)
put_bits(&s->pb, 16, frame->bs_code[1]);
if (s->sr_code[0] == 12)
put_bits(&s->pb, 8, s->sr_code[1]);
else if (s->sr_code[0] > 12)
put_bits(&s->pb, 16, s->sr_code[1]);
flush_put_bits(&s->pb);
crc = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, s->pb.buf,
put_bits_count(&s->pb) >> 3);
put_bits(&s->pb, 8, crc);
}
static void write_subframes(FlacEncodeContext *s)
{
int ch;
for (ch = 0; ch < s->channels; ch++) {
FlacSubframe *sub = &s->frame.subframes[ch];
int i, p, porder, psize;
int32_t *part_end;
int32_t *res = sub->residual;
int32_t *frame_end = &sub->residual[s->frame.blocksize];
/* subframe header */
put_bits(&s->pb, 1, 0);
put_bits(&s->pb, 6, sub->type_code);
put_bits(&s->pb, 1, !!sub->wasted);
if (sub->wasted)
put_bits(&s->pb, sub->wasted, 1);
/* subframe */
if (sub->type == FLAC_SUBFRAME_CONSTANT) {
put_sbits(&s->pb, sub->obits, res[0]);
} else if (sub->type == FLAC_SUBFRAME_VERBATIM) {
while (res < frame_end)
put_sbits(&s->pb, sub->obits, *res++);
} else {
/* warm-up samples */
for (i = 0; i < sub->order; i++)
put_sbits(&s->pb, sub->obits, *res++);
/* LPC coefficients */
if (sub->type == FLAC_SUBFRAME_LPC) {
int cbits = s->options.lpc_coeff_precision;
put_bits( &s->pb, 4, cbits-1);
put_sbits(&s->pb, 5, sub->shift);
for (i = 0; i < sub->order; i++)
put_sbits(&s->pb, cbits, sub->coefs[i]);
}
/* rice-encoded block */
put_bits(&s->pb, 2, sub->rc.coding_mode - 4);
/* partition order */
porder = sub->rc.porder;
psize = s->frame.blocksize >> porder;
put_bits(&s->pb, 4, porder);
/* residual */
part_end = &sub->residual[psize];
for (p = 0; p < 1 << porder; p++) {
int k = sub->rc.params[p];
put_bits(&s->pb, sub->rc.coding_mode, k);
while (res < part_end)
set_sr_golomb_flac(&s->pb, *res++, k, INT32_MAX, 0);
part_end = FFMIN(frame_end, part_end + psize);
}
}
}
}
static void write_frame_footer(FlacEncodeContext *s)
{
int crc;
flush_put_bits(&s->pb);
crc = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, s->pb.buf,
put_bits_count(&s->pb)>>3));
put_bits(&s->pb, 16, crc);
flush_put_bits(&s->pb);
}
static int write_frame(FlacEncodeContext *s, AVPacket *avpkt)
{
init_put_bits(&s->pb, avpkt->data, avpkt->size);
write_frame_header(s);
write_subframes(s);
write_frame_footer(s);
return put_bits_count(&s->pb) >> 3;
}
static int update_md5_sum(FlacEncodeContext *s, const void *samples)
{
const uint8_t *buf;
int buf_size = s->frame.blocksize * s->channels *
((s->avctx->bits_per_raw_sample + 7) / 8);
if (s->avctx->bits_per_raw_sample > 16 || HAVE_BIGENDIAN) {
av_fast_malloc(&s->md5_buffer, &s->md5_buffer_size, buf_size);
if (!s->md5_buffer)
return AVERROR(ENOMEM);
}
if (s->avctx->bits_per_raw_sample <= 16) {
buf = (const uint8_t *)samples;
#if HAVE_BIGENDIAN
s->dsp.bswap16_buf((uint16_t *)s->md5_buffer,
(const uint16_t *)samples, buf_size / 2);
buf = s->md5_buffer;
#endif
} else {
int i;
const int32_t *samples0 = samples;
uint8_t *tmp = s->md5_buffer;
for (i = 0; i < s->frame.blocksize * s->channels; i++) {
int32_t v = samples0[i] >> 8;
*tmp++ = (v ) & 0xFF;
*tmp++ = (v >> 8) & 0xFF;
*tmp++ = (v >> 16) & 0xFF;
}
buf = s->md5_buffer;
}
av_md5_update(s->md5ctx, buf, buf_size);
return 0;
}
static int flac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
const AVFrame *frame, int *got_packet_ptr)
{
FlacEncodeContext *s;
int frame_bytes, out_bytes, ret;
s = avctx->priv_data;
/* when the last block is reached, update the header in extradata */
if (!frame) {
s->max_framesize = s->max_encoded_framesize;
av_md5_final(s->md5ctx, s->md5sum);
write_streaminfo(s, avctx->extradata);
return 0;
}
/* change max_framesize for small final frame */
if (frame->nb_samples < s->frame.blocksize) {
s->max_framesize = ff_flac_get_max_frame_size(frame->nb_samples,
s->channels,
avctx->bits_per_raw_sample);
}
init_frame(s, frame->nb_samples);
copy_samples(s, frame->data[0]);
channel_decorrelation(s);
remove_wasted_bits(s);
frame_bytes = encode_frame(s);
/* fallback to verbatim mode if the compressed frame is larger than it
would be if encoded uncompressed. */
if (frame_bytes < 0 || frame_bytes > s->max_framesize) {
s->frame.verbatim_only = 1;
frame_bytes = encode_frame(s);
if (frame_bytes < 0) {
av_log(avctx, AV_LOG_ERROR, "Bad frame count\n");
return frame_bytes;
}
}
if ((ret = ff_alloc_packet2(avctx, avpkt, frame_bytes)))
return ret;
out_bytes = write_frame(s, avpkt);
s->frame_count++;
s->sample_count += frame->nb_samples;
if ((ret = update_md5_sum(s, frame->data[0])) < 0) {
av_log(avctx, AV_LOG_ERROR, "Error updating MD5 checksum\n");
return ret;
}
if (out_bytes > s->max_encoded_framesize)
s->max_encoded_framesize = out_bytes;
if (out_bytes < s->min_framesize)
s->min_framesize = out_bytes;
avpkt->pts = frame->pts;
avpkt->duration = ff_samples_to_time_base(avctx, frame->nb_samples);
avpkt->size = out_bytes;
*got_packet_ptr = 1;
return 0;
}
static av_cold int flac_encode_close(AVCodecContext *avctx)
{
if (avctx->priv_data) {
FlacEncodeContext *s = avctx->priv_data;
av_freep(&s->md5ctx);
av_freep(&s->md5_buffer);
ff_lpc_end(&s->lpc_ctx);
}
av_freep(&avctx->extradata);
avctx->extradata_size = 0;
#if FF_API_OLD_ENCODE_AUDIO
av_freep(&avctx->coded_frame);
#endif
return 0;
}
#define FLAGS AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM
static const AVOption options[] = {
{ "lpc_coeff_precision", "LPC coefficient precision", offsetof(FlacEncodeContext, options.lpc_coeff_precision), AV_OPT_TYPE_INT, {.i64 = 15 }, 0, MAX_LPC_PRECISION, FLAGS },
{ "lpc_type", "LPC algorithm", offsetof(FlacEncodeContext, options.lpc_type), AV_OPT_TYPE_INT, {.i64 = FF_LPC_TYPE_DEFAULT }, FF_LPC_TYPE_DEFAULT, FF_LPC_TYPE_NB-1, FLAGS, "lpc_type" },
{ "none", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_NONE }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
{ "fixed", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_FIXED }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
{ "levinson", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_LEVINSON }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
{ "cholesky", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_LPC_TYPE_CHOLESKY }, INT_MIN, INT_MAX, FLAGS, "lpc_type" },
{ "lpc_passes", "Number of passes to use for Cholesky factorization during LPC analysis", offsetof(FlacEncodeContext, options.lpc_passes), AV_OPT_TYPE_INT, {.i64 = 2 }, 1, INT_MAX, FLAGS },
{ "min_partition_order", NULL, offsetof(FlacEncodeContext, options.min_partition_order), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, MAX_PARTITION_ORDER, FLAGS },
{ "max_partition_order", NULL, offsetof(FlacEncodeContext, options.max_partition_order), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, MAX_PARTITION_ORDER, FLAGS },
{ "prediction_order_method", "Search method for selecting prediction order", offsetof(FlacEncodeContext, options.prediction_order_method), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, ORDER_METHOD_LOG, FLAGS, "predm" },
{ "estimation", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_EST }, INT_MIN, INT_MAX, FLAGS, "predm" },
{ "2level", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_2LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
{ "4level", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_4LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
{ "8level", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_8LEVEL }, INT_MIN, INT_MAX, FLAGS, "predm" },
{ "search", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_SEARCH }, INT_MIN, INT_MAX, FLAGS, "predm" },
{ "log", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = ORDER_METHOD_LOG }, INT_MIN, INT_MAX, FLAGS, "predm" },
{ "ch_mode", "Stereo decorrelation mode", offsetof(FlacEncodeContext, options.ch_mode), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, FLAC_CHMODE_MID_SIDE, FLAGS, "ch_mode" },
{ "auto", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = -1 }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
{ "indep", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_INDEPENDENT }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
{ "left_side", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_LEFT_SIDE }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
{ "right_side", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_RIGHT_SIDE }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
{ "mid_side", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = FLAC_CHMODE_MID_SIDE }, INT_MIN, INT_MAX, FLAGS, "ch_mode" },
{ NULL },
};
static const AVClass flac_encoder_class = {
"FLAC encoder",
av_default_item_name,
options,
LIBAVUTIL_VERSION_INT,
};
AVCodec ff_flac_encoder = {
.name = "flac",
.type = AVMEDIA_TYPE_AUDIO,
.id = AV_CODEC_ID_FLAC,
.priv_data_size = sizeof(FlacEncodeContext),
.init = flac_encode_init,
.encode2 = flac_encode_frame,
.close = flac_encode_close,
.capabilities = CODEC_CAP_SMALL_LAST_FRAME | CODEC_CAP_DELAY | CODEC_CAP_LOSSLESS,
.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
AV_SAMPLE_FMT_S32,
AV_SAMPLE_FMT_NONE },
.long_name = NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
.priv_class = &flac_encoder_class,
};