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authorMichael Niedermayer <michaelni@gmx.at>2006-07-15 23:43:38 +0000
committerMichael Niedermayer <michaelni@gmx.at>2006-07-15 23:43:38 +0000
commit408ec4e2a6c3fb40e14ac4f0fb2fb9e40ff3e6a3 (patch)
tree981867ca181d59ac2849f28241be9185f272c59c
parent6ce704bbedac2745b51bfdb11af2431f05a1dc23 (diff)
downloadffmpeg-408ec4e2a6c3fb40e14ac4f0fb2fb9e40ff3e6a3.tar.gz
calculate all coefficients for several orders during cholesky factorization, the resulting coefficients are not strictly optimal though as there is a small difference in the autocorrelation matrixes which is ignored for the smaller orders
Originally committed as revision 5758 to svn://svn.ffmpeg.org/ffmpeg/trunk
-rw-r--r--libavcodec/flacenc.c24
-rw-r--r--libavutil/lls.c64
-rw-r--r--libavutil/lls.h7
3 files changed, 55 insertions, 40 deletions
diff --git a/libavcodec/flacenc.c b/libavcodec/flacenc.c
index b72da9093f..af36976d77 100644
--- a/libavcodec/flacenc.c
+++ b/libavcodec/flacenc.c
@@ -742,35 +742,41 @@ static int lpc_calc_coefs(const int32_t *samples, int blocksize, int max_order,
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;
+ double var[MAX_LPC_ORDER+1], eval, weight;
for(pass=0; pass<use_lpc-1; pass++){
av_init_lls(&m[pass&1], max_order);
+ weight=0;
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= av_evaluate_lls(&m[(pass-1)&1], var+1, max_order-1);
eval= (512>>pass) + fabs(eval - var[0]);
for(j=0; j<=max_order; j++)
var[j]/= sqrt(eval);
- }
+ weight += 1/eval;
+ }else
+ weight++;
av_update_lls(&m[pass&1], var, 1.0);
}
- av_solve_lls(&m[pass&1], 0.001);
- opt_order= max_order; //FIXME
+ av_solve_lls(&m[pass&1], 0.001, 0);
}
- for(i=0; i<opt_order; i++)
- lpc[opt_order-1][i]= m[(pass-1)&1].coeff[i];
+ for(i=0; i<max_order; i++){
+ for(j=0; j<max_order; j++)
+ lpc[i][j]= m[(pass-1)&1].coeff[i][j];
+ ref[i]= sqrt(m[(pass-1)&1].variance[i] / weight) * (blocksize - max_order) / 4000;
+ }
+ for(i=max_order-1; i>0; i--)
+ ref[i] = ref[i-1] - ref[i];
}
+ opt_order = estimate_best_order(ref, max_order);
i = opt_order-1;
quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i]);
diff --git a/libavutil/lls.c b/libavutil/lls.c
index 0556d8c80f..50a5003763 100644
--- a/libavutil/lls.c
+++ b/libavutil/lls.c
@@ -49,12 +49,11 @@ void av_update_lls(LLSModel *m, double *var, double decay){
}
}
-double av_solve_lls(LLSModel *m, double threshold){
+void av_solve_lls(LLSModel *m, double threshold, int min_order){
int i,j,k;
double (*factor)[MAX_VARS+1]= &m->covariance[1][0];
double (*covar )[MAX_VARS+1]= &m->covariance[1][1];
double *covar_y = m->covariance[0];
- double variance;
int count= m->indep_count;
for(i=0; i<count; i++){
@@ -75,33 +74,34 @@ double av_solve_lls(LLSModel *m, double threshold){
for(i=0; i<count; i++){
double sum= covar_y[i+1];
for(k=i-1; k>=0; k--)
- sum -= factor[i][k]*m->coeff[k];
- m->coeff[i]= sum / factor[i][i];
+ sum -= factor[i][k]*m->coeff[0][k];
+ m->coeff[0][i]= sum / factor[i][i];
}
- for(i=count-1; i>=0; i--){
- double sum= m->coeff[i];
- for(k=i+1; k<count; k++)
- sum -= factor[k][i]*m->coeff[k];
- m->coeff[i]= sum / factor[i][i];
- }
+ for(j=count-1; j>=min_order; j--){
+ for(i=j; i>=0; i--){
+ double sum= m->coeff[0][i];
+ for(k=i+1; k<=j; k++)
+ sum -= factor[k][i]*m->coeff[j][k];
+ m->coeff[j][i]= sum / factor[i][i];
+ }
- variance= covar_y[0];
- for(i=0; i<count; i++){
- double sum= m->coeff[i]*covar[i][i] - 2*covar_y[i+1];
- for(j=0; j<i; j++)
- sum += 2*m->coeff[j]*covar[j][i];
- variance += m->coeff[i]*sum;
+ m->variance[j]= covar_y[0];
+ for(i=0; i<=j; i++){
+ double sum= m->coeff[j][i]*covar[i][i] - 2*covar_y[i+1];
+ for(k=0; k<i; k++)
+ sum += 2*m->coeff[j][k]*covar[k][i];
+ m->variance[j] += m->coeff[j][i]*sum;
+ }
}
- return variance;
}
-double av_evaluate_lls(LLSModel *m, double *param){
+double av_evaluate_lls(LLSModel *m, double *param, int order){
int i;
double out= 0;
- for(i=0; i<m->indep_count; i++)
- out+= param[i]*m->coeff[i];
+ for(i=0; i<=order; i++)
+ out+= param[i]*m->coeff[order][i];
return out;
}
@@ -113,27 +113,35 @@ double av_evaluate_lls(LLSModel *m, double *param){
int main(){
LLSModel m;
- int i;
+ int i, order;
av_init_lls(&m, 3);
for(i=0; i<100; i++){
double var[4];
double eval, variance;
+#if 0
var[1] = rand() / (double)RAND_MAX;
var[2] = rand() / (double)RAND_MAX;
var[3] = rand() / (double)RAND_MAX;
- var[2]= var[1] + var[3];
+ var[2]= var[1] + var[3]/2;
var[0] = var[1] + var[2] + var[3] + var[1]*var[2]/100;
-
- eval= av_evaluate_lls(&m, var+1);
+#else
+ var[0] = (rand() / (double)RAND_MAX - 0.5)*2;
+ var[1] = var[0] + rand() / (double)RAND_MAX - 0.5;
+ var[2] = var[1] + rand() / (double)RAND_MAX - 0.5;
+ var[3] = var[2] + rand() / (double)RAND_MAX - 0.5;
+#endif
av_update_lls(&m, var, 0.99);
- variance= av_solve_lls(&m, 0.001);
- av_log(NULL, AV_LOG_DEBUG, "real:%f pred:%f var:%f coeffs:%f %f %f\n",
- var[0], eval, sqrt(variance / (i+1)),
- m.coeff[0], m.coeff[1], m.coeff[2]);
+ av_solve_lls(&m, 0.001, 0);
+ for(order=0; order<3; order++){
+ eval= av_evaluate_lls(&m, var+1, order);
+ av_log(NULL, AV_LOG_DEBUG, "real:%f order:%d pred:%f var:%f coeffs:%f %f %f\n",
+ var[0], order, eval, sqrt(m.variance[order] / (i+1)),
+ m.coeff[order][0], m.coeff[order][1], m.coeff[order][2]);
+ }
}
return 0;
}
diff --git a/libavutil/lls.h b/libavutil/lls.h
index a75095faf9..5c603e467a 100644
--- a/libavutil/lls.h
+++ b/libavutil/lls.h
@@ -30,13 +30,14 @@
*/
typedef struct LLSModel{
double covariance[MAX_VARS+1][MAX_VARS+1];
- double coeff[MAX_VARS];
+ double coeff[MAX_VARS][MAX_VARS];
+ double variance[MAX_VARS];
int indep_count;
}LLSModel;
void av_init_lls(LLSModel *m, int indep_count);
void av_update_lls(LLSModel *m, double *param, double decay);
-double av_solve_lls(LLSModel *m, double threshold);
-double av_evaluate_lls(LLSModel *m, double *param);
+void av_solve_lls(LLSModel *m, double threshold, int min_order);
+double av_evaluate_lls(LLSModel *m, double *param, int order);
#endif