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Code Issues Releases Activity

flacenc: Allow more flexible shift calculation in LPC.

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Originally committed as revision 14789 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Ramiro Polla 2008-08-16 17:03:57 +00:00
parent 3cffbe090a
commit 51c796d012
1 changed files with 11 additions and 10 deletions
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21
libavcodec/flacenc.c
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@ -680,7 +680,7 @@ static void compute_lpc_coefs(const double *autoc, int max_order,
* Quantize LPC coefficients
*/
static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
int32_t *lpc_out, int *shift)
int32_t *lpc_out, int *shift, int max_shift, int zero_shift)
{
int i;
double cmax, error;
@ -697,14 +697,14 @@ static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
}
/* if maximum value quantizes to zero, return all zeros */
if(cmax * (1 << MAX_LPC_SHIFT) < 1.0) {
*shift = 0;
if(cmax * (1 << max_shift) < 1.0) {
*shift = zero_shift;
memset(lpc_out, 0, sizeof(int32_t) * order);
return;
}
/* calculate level shift which scales max coeff to available bits */
sh = MAX_LPC_SHIFT;
sh = max_shift;
while((cmax * (1 << sh) > qmax) && (sh > 0)) {
sh--;
}
@ -745,10 +745,10 @@ static int estimate_best_order(double *ref, int max_order)
/**
* Calculate LPC coefficients for multiple orders
*/
static int lpc_calc_coefs(FlacEncodeContext *s,
static int lpc_calc_coefs(DSPContext *s,
const int32_t *samples, int blocksize, int max_order,
int precision, int32_t coefs[][MAX_LPC_ORDER],
int *shift, int use_lpc, int omethod)
int *shift, int use_lpc, int omethod, int max_shift, int zero_shift)
{
double autoc[MAX_LPC_ORDER+1];
double ref[MAX_LPC_ORDER];
@ -759,7 +759,7 @@ static int lpc_calc_coefs(FlacEncodeContext *s,
assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER);
if(use_lpc == 1){
s->dsp.flac_compute_autocorr(samples, blocksize, max_order, autoc);
s->flac_compute_autocorr(samples, blocksize, max_order, autoc);
compute_lpc_coefs(autoc, max_order, lpc, ref);
}else{
@ -804,10 +804,10 @@ static int lpc_calc_coefs(FlacEncodeContext *s,
if(omethod == ORDER_METHOD_EST) {
opt_order = estimate_best_order(ref, max_order);
i = opt_order-1;
quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i]);
quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
} else {
for(i=0; i<max_order; i++) {
quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i]);
quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
}
}
@ -1042,7 +1042,8 @@ static int encode_residual(FlacEncodeContext *ctx, int ch)
}
/* LPC */
opt_order = lpc_calc_coefs(ctx, smp, n, max_order, precision, coefs, shift, ctx->options.use_lpc, omethod);
opt_order = lpc_calc_coefs(&ctx->dsp, smp, n, max_order, precision, coefs,
shift, ctx->options.use_lpc, omethod, MAX_LPC_SHIFT, 0);
if(omethod == ORDER_METHOD_2LEVEL ||
omethod == ORDER_METHOD_4LEVEL ||