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ab01b2b82a
FFmpeg/libavcodec/flacenc.c
Michael Niedermayer ab01b2b82a optionally (use_lpc=2) support Cholesky factorization for finding the lpc coeficients 
this will find the coefficients which minimize the sum of the squared errors,
  levinson-durbin recursion OTOH is only strictly correct if the autocorrelation matrix is a
  toeplitz matrix which it is only if the blocksize is infinite, this is also why applying
  a window (like the welch winodw we currently use) improves the lpc coefficients generated
  by levinson-durbin recursion ...

optionally (use_lpc>2) support iterative linear least abs() solver using cholesky
  factorization with adjusted weights in each iteration

compression gain for both is small, and multiple passes are of course dead slow

Originally committed as revision 5747 to svn://svn.ffmpeg.org/ffmpeg/trunk
2006-07-14 18:48:38 +00:00

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/**
* FLAC audio encoder
* Copyright (c) 2006 Justin Ruggles <jruggle@earthlink.net>
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avcodec.h"
#include "bitstream.h"
#include "crc.h"
#include "golomb.h"
#include "lls.h"
#define FLAC_MAX_CH 8
#define FLAC_MIN_BLOCKSIZE 16
#define FLAC_MAX_BLOCKSIZE 65535
#define FLAC_SUBFRAME_CONSTANT 0
#define FLAC_SUBFRAME_VERBATIM 1
#define FLAC_SUBFRAME_FIXED 8
#define FLAC_SUBFRAME_LPC 32
#define FLAC_CHMODE_NOT_STEREO 0
#define FLAC_CHMODE_LEFT_RIGHT 1
#define FLAC_CHMODE_LEFT_SIDE 8
#define FLAC_CHMODE_RIGHT_SIDE 9
#define FLAC_CHMODE_MID_SIDE 10
#define ORDER_METHOD_EST 0
#define ORDER_METHOD_2LEVEL 1
#define ORDER_METHOD_4LEVEL 2
#define ORDER_METHOD_8LEVEL 3
#define ORDER_METHOD_SEARCH 4
#define FLAC_STREAMINFO_SIZE 34
#define MIN_LPC_ORDER 1
#define MAX_LPC_ORDER 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;
int use_lpc;
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];
} FlacSubframe;
typedef struct FlacFrame {
FlacSubframe subframes[FLAC_MAX_CH];
int blocksize;
int bs_code[2];
uint8_t crc8;
int ch_mode;
} FlacFrame;
typedef struct FlacEncodeContext {
PutBitContext pb;
int channels;
int ch_code;
int samplerate;
int sr_code[2];
int blocksize;
int max_framesize;
uint32_t frame_count;
FlacFrame frame;
CompressionOptions options;
AVCodecContext *avctx;
} FlacEncodeContext;
static const int flac_samplerates[16] = {
0, 0, 0, 0,
8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000,
0, 0, 0, 0
};
static const int flac_blocksizes[16] = {
0,
192,
576, 1152, 2304, 4608,
0, 0,
256, 512, 1024, 2048, 4096, 8192, 16384, 32768
};
/**
* Writes 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->blocksize);
put_bits(&pb, 16, s->blocksize);
put_bits(&pb, 24, 0);
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 */
flush_put_bits(&pb);
/* total samples = 0 */
/* MD5 signature = 0 */
}
/**
* Sets blocksize based on samplerate
* Chooses 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 = flac_blocksizes[1];
target = (samplerate * block_time_ms) / 1000;
for(i=0; i<16; i++) {
if(target >= flac_blocksizes[i] && flac_blocksizes[i] > blocksize) {
blocksize = flac_blocksizes[i];
}
}
return blocksize;
}
static 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;
if(avctx->sample_fmt != SAMPLE_FMT_S16) {
return -1;
}
if(channels < 1 || channels > FLAC_MAX_CH) {
return -1;
}
s->channels = channels;
s->ch_code = s->channels-1;
/* find samplerate in table */
if(freq < 1)
return -1;
for(i=4; i<12; i++) {
if(freq == flac_samplerates[i]) {
s->samplerate = flac_samplerates[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;
}
av_log(avctx, AV_LOG_DEBUG, " compression: %d\n", s->options.compression_level);
level= s->options.compression_level;
if(level > 5) {
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})[level];
s->options.use_lpc = ((int[]){ 0, 0, 0, 1, 1, 1})[level];
s->options.min_prediction_order= ((int[]){ 2, 0, 0, 1, 1, 1})[level];
s->options.max_prediction_order= ((int[]){ 3, 4, 4, 6, 8, 8})[level];
s->options.prediction_order_method = ORDER_METHOD_EST;
s->options.min_partition_order = ((int[]){ 2, 2, 0, 0, 0, 0})[level];
s->options.max_partition_order = ((int[]){ 2, 2, 3, 3, 3, 8})[level];
/* set compression option overrides from AVCodecContext */
if(avctx->use_lpc >= 0) {
s->options.use_lpc = clip(avctx->use_lpc, 0, 11);
}
if(s->options.use_lpc == 1)
av_log(avctx, AV_LOG_DEBUG, " use lpc: Levinson-Durbin recursion with Welch window\n");
else if(s->options.use_lpc > 1)
av_log(avctx, AV_LOG_DEBUG, " use lpc: Cholesky factorization\n");
if(avctx->min_prediction_order >= 0) {
if(s->options.use_lpc) {
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;
}
} else {
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;
}
}
s->options.min_prediction_order = avctx->min_prediction_order;
}
if(avctx->max_prediction_order >= 0) {
if(s->options.use_lpc) {
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;
}
} else {
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;
}
}
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;
}
av_log(avctx, AV_LOG_DEBUG, " prediction order: %d, %d\n",
s->options.min_prediction_order, s->options.max_prediction_order);
if(avctx->prediction_order_method >= 0) {
if(avctx->prediction_order_method > ORDER_METHOD_SEARCH) {
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;
}
switch(avctx->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;
}
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;
}
av_log(avctx, AV_LOG_DEBUG, " partition order: %d, %d\n",
s->options.min_partition_order, s->options.max_partition_order);
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;
}
s->blocksize = avctx->frame_size;
} else {
s->blocksize = select_blocksize(s->samplerate, s->options.block_time_ms);
avctx->frame_size = s->blocksize;
}
av_log(avctx, AV_LOG_DEBUG, " block size: %d\n", s->blocksize);
/* 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 {
/* select LPC precision based on block size */
if( s->blocksize <= 192) s->options.lpc_coeff_precision = 7;
else if(s->blocksize <= 384) s->options.lpc_coeff_precision = 8;
else if(s->blocksize <= 576) s->options.lpc_coeff_precision = 9;
else if(s->blocksize <= 1152) s->options.lpc_coeff_precision = 10;
else if(s->blocksize <= 2304) s->options.lpc_coeff_precision = 11;
else if(s->blocksize <= 4608) s->options.lpc_coeff_precision = 12;
else if(s->blocksize <= 8192) s->options.lpc_coeff_precision = 13;
else if(s->blocksize <= 16384) s->options.lpc_coeff_precision = 14;
else s->options.lpc_coeff_precision = 15;
}
av_log(avctx, AV_LOG_DEBUG, " lpc precision: %d\n",
s->options.lpc_coeff_precision);
/* set maximum encoded frame size in verbatim mode */
if(s->channels == 2) {
s->max_framesize = 14 + ((s->blocksize * 33 + 7) >> 3);
} else {
s->max_framesize = 14 + (s->blocksize * s->channels * 2);
}
streaminfo = av_malloc(FLAC_STREAMINFO_SIZE);
write_streaminfo(s, streaminfo);
avctx->extradata = streaminfo;
avctx->extradata_size = FLAC_STREAMINFO_SIZE;
s->frame_count = 0;
avctx->coded_frame = avcodec_alloc_frame();
avctx->coded_frame->key_frame = 1;
return 0;
}
static void init_frame(FlacEncodeContext *s)
{
int i, ch;
FlacFrame *frame;
frame = &s->frame;
for(i=0; i<16; i++) {
if(s->blocksize == flac_blocksizes[i]) {
frame->blocksize = flac_blocksizes[i];
frame->bs_code[0] = i;
frame->bs_code[1] = 0;
break;
}
}
if(i == 16) {
frame->blocksize = s->blocksize;
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;
}
}
/**
* Copy channel-interleaved input samples into separate subframes
*/
static void copy_samples(FlacEncodeContext *s, 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];
}
}
}
#define rice_encode_count(sum, n, k) (((n)*((k)+1))+((sum-(n>>1))>>(k)))
static int find_optimal_param(uint32_t sum, int n)
{
int k, k_opt;
uint32_t nbits[MAX_RICE_PARAM+1];
k_opt = 0;
nbits[0] = UINT32_MAX;
for(k=0; k<=MAX_RICE_PARAM; k++) {
nbits[k] = rice_encode_count(sum, n, k);
if(nbits[k] < nbits[k_opt]) {
k_opt = k;
}
}
return k_opt;
}
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 = 0;
cnt = (n >> porder) - pred_order;
for(i=0; i<part; i++) {
if(i == 1) cnt = (n >> porder);
k = find_optimal_param(sums[i], cnt);
rc->params[i] = k;
all_bits += rice_encode_count(sums[i], cnt, k);
}
all_bits += (4 * part);
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++) {
sums[pmax][i] = 0;
while(res < res_end){
sums[pmax][i] += *(res++);
}
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 calc_rice_params_fixed(RiceContext *rc, int pmin, int pmax,
int32_t *data, int n, int pred_order,
int bps)
{
uint32_t bits;
pmin = get_max_p_order(pmin, n, pred_order);
pmax = get_max_p_order(pmax, n, pred_order);
bits = pred_order*bps + 6;
bits += calc_rice_params(rc, pmin, pmax, data, n, pred_order);
return bits;
}
static uint32_t calc_rice_params_lpc(RiceContext *rc, int pmin, int pmax,
int32_t *data, int n, int pred_order,
int bps, int precision)
{
uint32_t bits;
pmin = get_max_p_order(pmin, n, pred_order);
pmax = get_max_p_order(pmax, n, pred_order);
bits = pred_order*bps + 4 + 5 + pred_order*precision + 6;
bits += calc_rice_params(rc, pmin, pmax, data, n, pred_order);
return bits;
}
/**
* Apply Welch window function to audio block
*/
static void apply_welch_window(const int32_t *data, int len, double *w_data)
{
int i, n2;
double w;
double c;
n2 = (len >> 1);
c = 2.0 / (len - 1.0);
for(i=0; i<n2; i++) {
w = c - i - 1.0;
w = 1.0 - (w * w);
w_data[i] = data[i] * w;
w_data[len-1-i] = data[len-1-i] * w;
}
}
/**
* Calculates autocorrelation data from audio samples
* A Welch window function is applied before calculation.
*/
static void compute_autocorr(const int32_t *data, int len, int lag,
double *autoc)
{
int i, lag_ptr;
double tmp[len + lag];
double *data1= tmp + lag;
apply_welch_window(data, len, data1);
for(i=0; i<lag; i++){
autoc[i] = 1.0;
data1[i-lag]= 0.0;
}
for(i=0; i<len; i++){
for(lag_ptr= i-lag; lag_ptr<=i; lag_ptr++){
autoc[i-lag_ptr] += data1[i] * data1[lag_ptr];
}
}
}
/**
* Levinson-Durbin recursion.
* Produces LPC coefficients from autocorrelation data.
*/
static void compute_lpc_coefs(const double *autoc, int max_order,
double lpc[][MAX_LPC_ORDER], double *ref)
{
int i, j, i2;
double r, err, tmp;
double lpc_tmp[MAX_LPC_ORDER];
for(i=0; i<max_order; i++) lpc_tmp[i] = 0;
err = autoc[0];
for(i=0; i<max_order; i++) {
r = -autoc[i+1];
for(j=0; j<i; j++) {
r -= lpc_tmp[j] * autoc[i-j];
}
r /= err;
ref[i] = fabs(r);
err *= 1.0 - (r * r);
i2 = (i >> 1);
lpc_tmp[i] = r;
for(j=0; j<i2; j++) {
tmp = lpc_tmp[j];
lpc_tmp[j] += r * lpc_tmp[i-1-j];
lpc_tmp[i-1-j] += r * tmp;
}
if(i & 1) {
lpc_tmp[j] += lpc_tmp[j] * r;
}
for(j=0; j<=i; j++) {
lpc[i][j] = -lpc_tmp[j];
}
}
}
/**
* Quantize LPC coefficients
*/
static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
int32_t *lpc_out, int *shift)
{
int i;
double cmax, error;
int32_t qmax;
int sh;
/* define maximum levels */
qmax = (1 << (precision - 1)) - 1;
/* find maximum coefficient value */
cmax = 0.0;
for(i=0; i<order; i++) {
cmax= FFMAX(cmax, fabs(lpc_in[i]));
}
/* if maximum value quantizes to zero, return all zeros */
if(cmax * (1 << MAX_LPC_SHIFT) < 1.0) {
*shift = 0;
memset(lpc_out, 0, sizeof(int32_t) * order);
return;
}
/* calculate level shift which scales max coeff to available bits */
sh = MAX_LPC_SHIFT;
while((cmax * (1 << sh) > qmax) && (sh > 0)) {
sh--;
}
/* since negative shift values are unsupported in decoder, scale down
coefficients instead */
if(sh == 0 && cmax > qmax) {
double scale = ((double)qmax) / cmax;
for(i=0; i<order; i++) {
lpc_in[i] *= scale;
}
}
/* output quantized coefficients and level shift */
error=0;
for(i=0; i<order; i++) {
error += lpc_in[i] * (1 << sh);
lpc_out[i] = clip(lrintf(error), -qmax, qmax);
error -= lpc_out[i];
}
*shift = sh;
}
static int estimate_best_order(double *ref, int max_order)
{
int i, est;
est = 1;
for(i=max_order-1; i>=0; i--) {
if(ref[i] > 0.10) {
est = i+1;
break;
}
}
return est;
}
/**
* Calculate LPC coefficients for multiple orders
*/
static int lpc_calc_coefs(const int32_t *samples, int blocksize, int max_order,
int precision, int32_t coefs[][MAX_LPC_ORDER],
int *shift, int use_lpc)
{
double autoc[MAX_LPC_ORDER+1];
double ref[MAX_LPC_ORDER];
double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER];
int i, j, pass;
int opt_order;
assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER);
if(use_lpc == 1){
compute_autocorr(samples, blocksize, max_order+1, autoc);
compute_lpc_coefs(autoc, max_order, lpc, ref);
opt_order = estimate_best_order(ref, max_order);
}else{
LLSModel m[2];
double var[MAX_LPC_ORDER+1], eval;
for(pass=0; pass<use_lpc-1; pass++){
av_init_lls(&m[pass&1], max_order/*3*/);
for(i=max_order; i<blocksize; i++){
for(j=0; j<=max_order; j++)
var[j]= samples[i-j];
if(pass){
eval= av_evaluate_lls(&m[(pass-1)&1], var+1);
eval= (512>>pass) + fabs(eval - var[0]);
for(j=0; j<=max_order; j++)
var[j]= samples[i-j] / sqrt(eval);
}
av_update_lls(&m[pass&1], var, 1.0);
}
av_solve_lls(&m[pass&1], 0.001);
opt_order= max_order; //FIXME
}
for(i=0; i<opt_order; i++)
lpc[opt_order-1][i]= m[(pass-1)&1].coeff[i];
}
i = opt_order-1;
quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i]);
return opt_order;
}
static void encode_residual_verbatim(int32_t *res, int32_t *smp, int n)
{
assert(n > 0);
memcpy(res, smp, n * sizeof(int32_t));
}
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){
for(i=order; i<n; i++)
res[i]= smp[i] - 2*smp[i-1] + smp[i-2];
}else if(order==3){
for(i=order; i<n; i++)
res[i]= smp[i] - 3*smp[i-1] + 3*smp[i-2] - smp[i-3];
}else{
for(i=order; i<n; i++)
res[i]= smp[i] - 4*smp[i-1] + 6*smp[i-2] - 4*smp[i-3] + smp[i-4];
}
}
static void encode_residual_lpc(int32_t *res, const int32_t *smp, int n,
int order, const int32_t *coefs, int shift)
{
int i, j;
int32_t pred;
for(i=0; i<order; i++) {
res[i] = smp[i];
}
for(i=order; i<n; i++) {
pred = 0;
for(j=0; j<order; j++) {
pred += coefs[j] * smp[i-j-1];
}
res[i] = smp[i] - (pred >> shift);
}
}
static int encode_residual(FlacEncodeContext *ctx, int ch)
{
int i, n;
int min_order, max_order, opt_order, precision;
int min_porder, max_porder;
FlacFrame *frame;
FlacSubframe *sub;
int32_t coefs[MAX_LPC_ORDER][MAX_LPC_ORDER];
int shift[MAX_LPC_ORDER];
int32_t *res, *smp;
frame = &ctx->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 sub->obits;
}
/* VERBATIM */
if(n < 5) {
sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;
encode_residual_verbatim(res, smp, n);
return sub->obits * n;
}
min_order = ctx->options.min_prediction_order;
max_order = ctx->options.max_prediction_order;
min_porder = ctx->options.min_partition_order;
max_porder = ctx->options.max_partition_order;
precision = ctx->options.lpc_coeff_precision;
/* FIXED */
if(!ctx->options.use_lpc || max_order == 0 || (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] = calc_rice_params_fixed(&sub->rc, min_porder, max_porder, res,
n, i, sub->obits);
if(bits[i] < bits[opt_order]) {
opt_order = i;
}
}
sub->order = opt_order;
sub->type = FLAC_SUBFRAME_FIXED;
sub->type_code = sub->type | sub->order;
if(sub->order != max_order) {
encode_residual_fixed(res, smp, n, sub->order);
return calc_rice_params_fixed(&sub->rc, min_porder, max_porder, res, n,
sub->order, sub->obits);
}
return bits[sub->order];
}
/* LPC */
sub->order = lpc_calc_coefs(smp, n, max_order, precision, coefs, shift, ctx->options.use_lpc);
sub->type = FLAC_SUBFRAME_LPC;
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);
return calc_rice_params_lpc(&sub->rc, min_porder, max_porder, res, n, sub->order,
sub->obits, precision);
}
static int encode_residual_v(FlacEncodeContext *ctx, int ch)
{
int i, n;
FlacFrame *frame;
FlacSubframe *sub;
int32_t *res, *smp;
frame = &ctx->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 sub->obits;
}
/* VERBATIM */
sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;
encode_residual_verbatim(res, smp, n);
return sub->obits * n;
}
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] += ABS((lt + rt) >> 1);
sum[3] += ABS(lt - rt);
sum[0] += ABS(lt);
sum[1] += ABS(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_LEFT_RIGHT;
} 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 *ctx)
{
FlacFrame *frame;
int32_t *left, *right;
int i, n;
frame = &ctx->frame;
n = frame->blocksize;
left = frame->subframes[0].samples;
right = frame->subframes[1].samples;
if(ctx->channels != 2) {
frame->ch_mode = FLAC_CHMODE_NOT_STEREO;
return;
}
frame->ch_mode = estimate_stereo_mode(left, right, n);
/* perform decorrelation and adjust bits-per-sample */
if(frame->ch_mode == FLAC_CHMODE_LEFT_RIGHT) {
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 put_sbits(PutBitContext *pb, int bits, int32_t val)
{
assert(bits >= 0 && bits <= 31);
put_bits(pb, bits, val & ((1<<bits)-1));
}
static void write_utf8(PutBitContext *pb, uint32_t val)
{
int bytes, shift;
if(val < 0x80){
put_bits(pb, 8, val);
return;
}
bytes= (av_log2(val)+4) / 5;
shift = (bytes - 1) * 6;
put_bits(pb, 8, (256 - (256>>bytes)) | (val >> shift));
while(shift >= 6){
shift -= 6;
put_bits(pb, 8, 0x80 | ((val >> shift) & 0x3F));
}
}
static void output_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_NOT_STEREO) {
put_bits(&s->pb, 4, s->ch_code);
} 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_crc07, 0, s->pb.buf, put_bits_count(&s->pb)>>3);
put_bits(&s->pb, 8, crc);
}
static void output_subframe_constant(FlacEncodeContext *s, int ch)
{
FlacSubframe *sub;
int32_t res;
sub = &s->frame.subframes[ch];
res = sub->residual[0];
put_sbits(&s->pb, sub->obits, res);
}
static void output_subframe_verbatim(FlacEncodeContext *s, int ch)
{
int i;
FlacFrame *frame;
FlacSubframe *sub;
int32_t res;
frame = &s->frame;
sub = &frame->subframes[ch];
for(i=0; i<frame->blocksize; i++) {
res = sub->residual[i];
put_sbits(&s->pb, sub->obits, res);
}
}
static void output_residual(FlacEncodeContext *ctx, int ch)
{
int i, j, p, n, parts;
int k, porder, psize, res_cnt;
FlacFrame *frame;
FlacSubframe *sub;
int32_t *res;
frame = &ctx->frame;
sub = &frame->subframes[ch];
res = sub->residual;
n = frame->blocksize;
/* rice-encoded block */
put_bits(&ctx->pb, 2, 0);
/* partition order */
porder = sub->rc.porder;
psize = n >> porder;
parts = (1 << porder);
put_bits(&ctx->pb, 4, porder);
res_cnt = psize - sub->order;
/* residual */
j = sub->order;
for(p=0; p<parts; p++) {
k = sub->rc.params[p];
put_bits(&ctx->pb, 4, k);
if(p == 1) res_cnt = psize;
for(i=0; i<res_cnt && j<n; i++, j++) {
set_sr_golomb_flac(&ctx->pb, res[j], k, INT32_MAX, 0);
}
}
}
static void output_subframe_fixed(FlacEncodeContext *ctx, int ch)
{
int i;
FlacFrame *frame;
FlacSubframe *sub;
frame = &ctx->frame;
sub = &frame->subframes[ch];
/* warm-up samples */
for(i=0; i<sub->order; i++) {
put_sbits(&ctx->pb, sub->obits, sub->residual[i]);
}
/* residual */
output_residual(ctx, ch);
}
static void output_subframe_lpc(FlacEncodeContext *ctx, int ch)
{
int i, cbits;
FlacFrame *frame;
FlacSubframe *sub;
frame = &ctx->frame;
sub = &frame->subframes[ch];
/* warm-up samples */
for(i=0; i<sub->order; i++) {
put_sbits(&ctx->pb, sub->obits, sub->residual[i]);
}
/* LPC coefficients */
cbits = ctx->options.lpc_coeff_precision;
put_bits(&ctx->pb, 4, cbits-1);
put_sbits(&ctx->pb, 5, sub->shift);
for(i=0; i<sub->order; i++) {
put_sbits(&ctx->pb, cbits, sub->coefs[i]);
}
/* residual */
output_residual(ctx, ch);
}
static void output_subframes(FlacEncodeContext *s)
{
FlacFrame *frame;
FlacSubframe *sub;
int ch;
frame = &s->frame;
for(ch=0; ch<s->channels; ch++) {
sub = &frame->subframes[ch];
/* 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) {
output_subframe_constant(s, ch);
} else if(sub->type == FLAC_SUBFRAME_VERBATIM) {
output_subframe_verbatim(s, ch);
} else if(sub->type == FLAC_SUBFRAME_FIXED) {
output_subframe_fixed(s, ch);
} else if(sub->type == FLAC_SUBFRAME_LPC) {
output_subframe_lpc(s, ch);
}
}
}
static void output_frame_footer(FlacEncodeContext *s)
{
int crc;
flush_put_bits(&s->pb);
crc = bswap_16(av_crc(av_crc8005, 0, s->pb.buf, put_bits_count(&s->pb)>>3));
put_bits(&s->pb, 16, crc);
flush_put_bits(&s->pb);
}
static int flac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
int buf_size, void *data)
{
int ch;
FlacEncodeContext *s;
int16_t *samples = data;
int out_bytes;
s = avctx->priv_data;
s->blocksize = avctx->frame_size;
init_frame(s);
copy_samples(s, samples);
channel_decorrelation(s);
for(ch=0; ch<s->channels; ch++) {
encode_residual(s, ch);
}
init_put_bits(&s->pb, frame, buf_size);
output_frame_header(s);
output_subframes(s);
output_frame_footer(s);
out_bytes = put_bits_count(&s->pb) >> 3;
if(out_bytes > s->max_framesize || out_bytes >= buf_size) {
/* frame too large. use verbatim mode */
for(ch=0; ch<s->channels; ch++) {
encode_residual_v(s, ch);
}
init_put_bits(&s->pb, frame, buf_size);
output_frame_header(s);
output_subframes(s);
output_frame_footer(s);
out_bytes = put_bits_count(&s->pb) >> 3;
if(out_bytes > s->max_framesize || out_bytes >= buf_size) {
/* still too large. must be an error. */
av_log(avctx, AV_LOG_ERROR, "error encoding frame\n");
return -1;
}
}
s->frame_count++;
return out_bytes;
}
static int flac_encode_close(AVCodecContext *avctx)
{
av_freep(&avctx->extradata);
avctx->extradata_size = 0;
av_freep(&avctx->coded_frame);
return 0;
}
AVCodec flac_encoder = {
"flac",
CODEC_TYPE_AUDIO,
CODEC_ID_FLAC,
sizeof(FlacEncodeContext),
flac_encode_init,
flac_encode_frame,
flac_encode_close,
NULL,
.capabilities = CODEC_CAP_SMALL_LAST_FRAME,
};
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