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Avoid duplicating compute_lpc_coefs() function in both the RA288 and AAC decoders.

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Originally committed as revision 15193 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Vitor Sessak
2008-09-04 11:03:14 +00:00
parent 287ba997b5
commit 1be0fc2909
4 changed files with 69 additions and 95 deletions
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48
libavcodec/lpc.c
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@@ -21,46 +21,11 @@
#include "libavutil/lls.h"
#include "dsputil.h"
#define LPC_USE_DOUBLE
#include "lpc.h"
/**
* 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;
double err = autoc[0];
double lpc_tmp[MAX_LPC_ORDER];
for(i=0; i<max_order; i++) {
double 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);
lpc_tmp[i] = r;
for(j=0; j < i>>1; j++) {
double 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
*/
@@ -106,7 +71,7 @@ static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
/* output quantized coefficients and level shift */
error=0;
for(i=0; i<order; i++) {
error += lpc_in[i] * (1 << sh);
error -= lpc_in[i] * (1 << sh);
lpc_out[i] = av_clip(lrintf(error), -qmax, qmax);
error -= lpc_out[i];
}
@@ -147,7 +112,10 @@ int ff_lpc_calc_coefs(DSPContext *s,
if(use_lpc == 1){
s->flac_compute_autocorr(samples, blocksize, max_order, autoc);
compute_lpc_coefs(autoc, max_order, lpc, ref);
compute_lpc_coefs(autoc, max_order, &lpc[0][0], MAX_LPC_ORDER, 0, 1);
for(i=0; i<max_order; i++)
ref[i] = fabs(lpc[i][i]);
}else{
LLSModel m[2];
double var[MAX_LPC_ORDER+1], weight;
@@ -179,7 +147,7 @@ int ff_lpc_calc_coefs(DSPContext *s,
for(i=0; i<max_order; i++){
for(j=0; j<max_order; j++)
lpc[i][j]= m[(pass-1)&1].coeff[i][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--)