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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/crc.h"
#include "libavutil/md5.h"
#include "avcodec.h"
#include "get_bits.h"
#include "dsputil.h"
#include "golomb.h"
#include "lpc.h"
#include "flac.h"
#include "flacdata.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
#define MAX_RICE_PARAM 14
typedef struct CompressionOptions {
int compression_level;
int block_time_ms;
enum AVLPCType 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;
} CompressionOptions;
typedef struct RiceContext {
int porder;
int params[MAX_PARTITIONS];
} RiceContext;
typedef struct FlacSubframe {
int type;
int type_code;
int obits;
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 {
PutBitContext pb;
int channels;
int samplerate;
int sr_code[2];
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;
DSPContext dsp;
struct AVMD5 *md5ctx;
} 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, 15); /* bits per 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;
assert(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 AV_LPC_TYPE_NONE:
av_log(avctx, AV_LOG_DEBUG, " lpc type: None\n");
break;
case AV_LPC_TYPE_FIXED:
av_log(avctx, AV_LOG_DEBUG, " lpc type: Fixed pre-defined coefficients\n");
break;
case AV_LPC_TYPE_LEVINSON:
av_log(avctx, AV_LOG_DEBUG, " lpc type: Levinson-Durbin recursion with Welch window\n");
break;
case AV_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;
uint8_t *streaminfo;
s->avctx = avctx;
dsputil_init(&s->dsp, avctx);
if (avctx->sample_fmt != SAMPLE_FMT_S16)
return -1;
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];
s->options.lpc_type = ((int[]){ AV_LPC_TYPE_FIXED, AV_LPC_TYPE_FIXED, AV_LPC_TYPE_FIXED,
AV_LPC_TYPE_LEVINSON, AV_LPC_TYPE_LEVINSON, AV_LPC_TYPE_LEVINSON,
AV_LPC_TYPE_LEVINSON, AV_LPC_TYPE_LEVINSON, AV_LPC_TYPE_LEVINSON,
AV_LPC_TYPE_LEVINSON, AV_LPC_TYPE_LEVINSON, AV_LPC_TYPE_LEVINSON,
AV_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];
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];
s->options.min_partition_order = ((int[]){ 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})[level];
s->options.max_partition_order = ((int[]){ 2, 2, 3, 3, 3, 8, 8, 8, 8, 8, 8, 8, 8})[level];
/* set compression option overrides from AVCodecContext */
#if FF_API_USE_LPC
/* for compatibility with deprecated AVCodecContext.use_lpc */
if (avctx->use_lpc == 0) {
s->options.lpc_type = AV_LPC_TYPE_FIXED;
} else if (avctx->use_lpc == 1) {
s->options.lpc_type = AV_LPC_TYPE_LEVINSON;
} else if (avctx->use_lpc > 1) {
s->options.lpc_type = AV_LPC_TYPE_CHOLESKY;
s->options.lpc_passes = avctx->use_lpc - 1;
}
#endif
if (avctx->lpc_type > AV_LPC_TYPE_DEFAULT) {
if (avctx->lpc_type > AV_LPC_TYPE_CHOLESKY) {
av_log(avctx, AV_LOG_ERROR, "unknown lpc type: %d\n", avctx->lpc_type);
return -1;
}
s->options.lpc_type = avctx->lpc_type;
if (s->options.lpc_type == AV_LPC_TYPE_CHOLESKY) {
if (avctx->lpc_passes < 0) {
// default number of passes for Cholesky
s->options.lpc_passes = 2;
} else if (avctx->lpc_passes == 0) {
av_log(avctx, AV_LOG_ERROR, "invalid number of lpc passes: %d\n",
avctx->lpc_passes);
return -1;
} else {
s->options.lpc_passes = avctx->lpc_passes;
}
}
}
if (s->options.lpc_type == AV_LPC_TYPE_NONE) {
s->options.min_prediction_order = 0;
} else if (avctx->min_prediction_order >= 0) {
if (s->options.lpc_type == AV_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 == AV_LPC_TYPE_NONE) {
s->options.max_prediction_order = 0;
} else if (avctx->max_prediction_order >= 0) {
if (s->options.lpc_type == AV_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->prediction_order_method >= 0) {
if (avctx->prediction_order_method > ORDER_METHOD_LOG) {
av_log(avctx, AV_LOG_ERROR, "invalid prediction order method: %d\n",
avctx->prediction_order_method);
return -1;
}
s->options.prediction_order_method = avctx->prediction_order_method;
}
if (avctx->min_partition_order >= 0) {
if (avctx->min_partition_order > MAX_PARTITION_ORDER) {
av_log(avctx, AV_LOG_ERROR, "invalid min partition order: %d\n",
avctx->min_partition_order);
return -1;
}
s->options.min_partition_order = avctx->min_partition_order;
}
if (avctx->max_partition_order >= 0) {
if (avctx->max_partition_order > MAX_PARTITION_ORDER) {
av_log(avctx, AV_LOG_ERROR, "invalid max partition order: %d\n",
avctx->max_partition_order);
return -1;
}
s->options.max_partition_order = avctx->max_partition_order;
}
if (s->options.max_partition_order < s->options.min_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 -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 LPC precision */
if (avctx->lpc_coeff_precision > 0) {
if (avctx->lpc_coeff_precision > MAX_LPC_PRECISION) {
av_log(avctx, AV_LOG_ERROR, "invalid lpc coeff precision: %d\n",
avctx->lpc_coeff_precision);
return -1;
}
s->options.lpc_coeff_precision = avctx->lpc_coeff_precision;
} else {
/* default LPC precision */
s->options.lpc_coeff_precision = 15;
}
/* set maximum encoded frame size in verbatim mode */
s->max_framesize = ff_flac_get_max_frame_size(s->avctx->frame_size,
s->channels, 16);
/* initialize MD5 context */
s->md5ctx = av_malloc(av_md5_size);
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;
avctx->coded_frame = avcodec_alloc_frame();
if (!avctx->coded_frame)
return AVERROR(ENOMEM);
dprint_compression_options(s);
return 0;
}
static void init_frame(FlacEncodeContext *s)
{
int i, ch;
FlacFrame *frame;
frame = &s->frame;
for (i = 0; i < 16; i++) {
if (s->avctx->frame_size == 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 = s->avctx->frame_size;
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++)
frame->subframes[ch].obits = 16;
frame->verbatim_only = 0;
}
/**
* Copy channel-interleaved input samples into separate subframes.
*/
static void copy_samples(FlacEncodeContext *s, const int16_t *samples)
{
int i, j, ch;
FlacFrame *frame;
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] = samples[j];
}
static int rice_count_exact(int32_t *res, int n, int k)
{
int i;
int 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 int subframe_count_exact(FlacEncodeContext *s, FlacSubframe *sub,
int pred_order)
{
int p, porder, psize;
int i, part_end;
int 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 += 4;
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(uint32_t sum, int n)
{
int k;
uint32_t sum2;
if (sum <= n >> 1)
return 0;
sum2 = sum - (n >> 1);
k = av_log2(n < 256 ? FASTDIV(sum2, n) : sum2 / n);
return FFMIN(k, MAX_RICE_PARAM);
}
static uint32_t calc_optimal_rice_params(RiceContext *rc, int porder,
uint32_t *sums, int n, int pred_order)
{
int i;
int k, cnt, part;
uint32_t all_bits;
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);
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,
uint32_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++) {
uint32_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 uint32_t calc_rice_params(RiceContext *rc, int pmin, int pmax,
int32_t *data, int n, int pred_order)
{
int i;
uint32_t bits[MAX_PARTITION_ORDER+1];
int opt_porder;
RiceContext tmp_rc;
uint32_t *udata;
uint32_t sums[MAX_PARTITION_ORDER+1][MAX_PARTITIONS];
assert(pmin >= 0 && pmin <= MAX_PARTITION_ORDER);
assert(pmax >= 0 && pmax <= MAX_PARTITION_ORDER);
assert(pmin <= pmax);
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 uint32_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);
uint32_t bits = 8 + pred_order * sub->obits + 2 + 4;
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;
}
}
}
#define LPC1(x) {\
int c = coefs[(x)-1];\
p0 += c * s;\
s = smp[i-(x)+1];\
p1 += c * s;\
}
static av_always_inline void encode_residual_lpc_unrolled(int32_t *res,
const int32_t *smp, int n, int order,
const int32_t *coefs, int shift, int big)
{
int i;
for (i = order; i < n; i += 2) {
int s = smp[i-order];
int p0 = 0, p1 = 0;
if (big) {
switch (order) {
case 32: LPC1(32)
case 31: LPC1(31)
case 30: LPC1(30)
case 29: LPC1(29)
case 28: LPC1(28)
case 27: LPC1(27)
case 26: LPC1(26)
case 25: LPC1(25)
case 24: LPC1(24)
case 23: LPC1(23)
case 22: LPC1(22)
case 21: LPC1(21)
case 20: LPC1(20)
case 19: LPC1(19)
case 18: LPC1(18)
case 17: LPC1(17)
case 16: LPC1(16)
case 15: LPC1(15)
case 14: LPC1(14)
case 13: LPC1(13)
case 12: LPC1(12)
case 11: LPC1(11)
case 10: LPC1(10)
case 9: LPC1( 9)
LPC1( 8)
LPC1( 7)
LPC1( 6)
LPC1( 5)
LPC1( 4)
LPC1( 3)
LPC1( 2)
LPC1( 1)
}
} else {
switch (order) {
case 8: LPC1( 8)
case 7: LPC1( 7)
case 6: LPC1( 6)
case 5: LPC1( 5)
case 4: LPC1( 4)
case 3: LPC1( 3)
case 2: LPC1( 2)
case 1: LPC1( 1)
}
}
res[i ] = smp[i ] - (p0 >> shift);
res[i+1] = smp[i+1] - (p1 >> shift);
}
}
static void encode_residual_lpc(int32_t *res, const int32_t *smp, int n,
int order, const int32_t *coefs, int shift)
{
int i;
for (i = 0; i < order; i++)
res[i] = smp[i];
#if CONFIG_SMALL
for (i = order; i < n; i += 2) {
int j;
int s = smp[i];
int p0 = 0, p1 = 0;
for (j = 0; j < order; j++) {
int c = coefs[j];
p1 += c * s;
s = smp[i-j-1];
p0 += c * s;
}
res[i ] = smp[i ] - (p0 >> shift);
res[i+1] = smp[i+1] - (p1 >> shift);
}
#else
switch (order) {
case 1: encode_residual_lpc_unrolled(res, smp, n, 1, coefs, shift, 0); break;
case 2: encode_residual_lpc_unrolled(res, smp, n, 2, coefs, shift, 0); break;
case 3: encode_residual_lpc_unrolled(res, smp, n, 3, coefs, shift, 0); break;
case 4: encode_residual_lpc_unrolled(res, smp, n, 4, coefs, shift, 0); break;
case 5: encode_residual_lpc_unrolled(res, smp, n, 5, coefs, shift, 0); break;
case 6: encode_residual_lpc_unrolled(res, smp, n, 6, coefs, shift, 0); break;
case 7: encode_residual_lpc_unrolled(res, smp, n, 7, coefs, shift, 0); break;
case 8: encode_residual_lpc_unrolled(res, smp, n, 8, coefs, shift, 0); break;
default: encode_residual_lpc_unrolled(res, smp, n, order, coefs, shift, 1); break;
}
#endif
}
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 == AV_LPC_TYPE_NONE ||
s->options.lpc_type == AV_LPC_TYPE_FIXED || n <= max_order) {
uint32_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->dsp, 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;
uint32_t bits[1 << ORDER_METHOD_8LEVEL];
int order;
int opt_index = levels-1;
opt_order = max_order-1;
bits[opt_index] = UINT32_MAX;
for (i = levels-1; i >= 0; i--) {
order = min_order + (((max_order-min_order+1) * (i+1)) / levels)-1;
if (order < 0)
order = 0;
encode_residual_lpc(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
uint32_t bits[MAX_LPC_ORDER];
opt_order = 0;
bits[0] = UINT32_MAX;
for (i = min_order-1; i < max_order; i++) {
encode_residual_lpc(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) {
uint32_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;
encode_residual_lpc(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];
encode_residual_lpc(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 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, 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
return count >> 3;
}
static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n)
{
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);
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;
if (best == 0) {
return FLAC_CHMODE_INDEPENDENT;
} else if (best == 1) {
return FLAC_CHMODE_LEFT_SIDE;
} else if (best == 2) {
return FLAC_CHMODE_RIGHT_SIDE;
} else {
return FLAC_CHMODE_MID_SIDE;
}
}
/**
* 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;
}
frame->ch_mode = estimate_stereo_mode(left, right, n);
/* 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);
put_bits(&s->pb, 3, 4); /* bits-per-sample 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, 0); /* no wasted bits */
/* 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, 0);
/* 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, 4, 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, uint8_t *frame, int buf_size)
{
init_put_bits(&s->pb, frame, buf_size);
write_frame_header(s);
write_subframes(s);
write_frame_footer(s);
return put_bits_count(&s->pb) >> 3;
}
static void update_md5_sum(FlacEncodeContext *s, const int16_t *samples)
{
#if HAVE_BIGENDIAN
int i;
for (i = 0; i < s->frame.blocksize * s->channels; i++) {
int16_t smp = av_le2ne16(samples[i]);
av_md5_update(s->md5ctx, (uint8_t *)&smp, 2);
}
#else
av_md5_update(s->md5ctx, (const uint8_t *)samples, s->frame.blocksize*s->channels*2);
#endif
}
static int flac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
int buf_size, void *data)
{
FlacEncodeContext *s;
const int16_t *samples = data;
int frame_bytes, out_bytes;
s = avctx->priv_data;
/* when the last block is reached, update the header in extradata */
if (!data) {
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 (avctx->frame_size < s->frame.blocksize) {
s->max_framesize = ff_flac_get_max_frame_size(avctx->frame_size,
s->channels, 16);
}
init_frame(s);
copy_samples(s, samples);
channel_decorrelation(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 > s->max_framesize) {
s->frame.verbatim_only = 1;
frame_bytes = encode_frame(s);
}
if (buf_size < frame_bytes) {
av_log(avctx, AV_LOG_ERROR, "output buffer too small\n");
return 0;
}
out_bytes = write_frame(s, frame, buf_size);
s->frame_count++;
avctx->coded_frame->pts = s->sample_count;
s->sample_count += avctx->frame_size;
update_md5_sum(s, samples);
if (out_bytes > s->max_encoded_framesize)
s->max_encoded_framesize = out_bytes;
if (out_bytes < s->min_framesize)
s->min_framesize = out_bytes;
return out_bytes;
}
static av_cold int flac_encode_close(AVCodecContext *avctx)
{
if (avctx->priv_data) {
FlacEncodeContext *s = avctx->priv_data;
av_freep(&s->md5ctx);
}
av_freep(&avctx->extradata);
avctx->extradata_size = 0;
av_freep(&avctx->coded_frame);
return 0;
}
AVCodec flac_encoder = {
"flac",
AVMEDIA_TYPE_AUDIO,
CODEC_ID_FLAC,
sizeof(FlacEncodeContext),
flac_encode_init,
flac_encode_frame,
flac_encode_close,
NULL,
.capabilities = CODEC_CAP_SMALL_LAST_FRAME | CODEC_CAP_DELAY,
.sample_fmts = (const enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
.long_name = NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
};