From 306d7f5a308e30ce10ba1a1dcdbeeb81de3b2872 Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jmvalin@jmvalin.ca>
Date: Mon, 16 Dec 2013 01:08:21 -0500
Subject: [PATCH] fixed-point: slight (but free) accuracy improvement in
compute_band_energies()
Also moves the VSHR32() condition outside the loop just in case some compilers
don't optimize that properly.
---
celt/bands.c | 35 ++++++++++++++++++++---------------
celt/bands.h | 2 +-
celt/celt_encoder.c | 6 +++---
3 files changed, 24 insertions(+), 19 deletions(-)
diff --git a/celt/bands.c b/celt/bands.c
index 73346445c..ee2309123 100644
--- a/celt/bands.c
+++ b/celt/bands.c
@@ -92,11 +92,11 @@ static int bitexact_log2tan(int isin,int icos)
#ifdef FIXED_POINT
/* Compute the amplitude (sqrt energy) in each of the bands */
-void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *bandE, int end, int C, int M)
+void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *bandE, int end, int C, int LM)
{
int i, c, N;
const opus_int16 *eBands = m->eBands;
- N = M*m->shortMdctSize;
+ N = m->shortMdctSize<<LM;
c=0; do {
for (i=0;i<end;i++)
{
@@ -104,18 +104,23 @@ void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *band
opus_val32 maxval=0;
opus_val32 sum = 0;
- j=M*eBands[i]; do {
- maxval = MAX32(maxval, X[j+c*N]);
- maxval = MAX32(maxval, -X[j+c*N]);
- } while (++j<M*eBands[i+1]);
-
+ maxval = celt_maxabs32(&X[c*N+(eBands[i]<<LM)], (eBands[i+1]-eBands[i])<<LM);
if (maxval > 0)
{
- int shift = celt_ilog2(maxval)-10;
- j=M*eBands[i]; do {
- sum = MAC16_16(sum, EXTRACT16(VSHR32(X[j+c*N],shift)),
- EXTRACT16(VSHR32(X[j+c*N],shift)));
- } while (++j<M*eBands[i+1]);
+ int shift = celt_ilog2(maxval) - 14 + (((m->logN[i]>>BITRES)+LM+1)>>1);
+ j=eBands[i]<<LM;
+ if (shift>0)
+ {
+ do {
+ sum = MAC16_16(sum, EXTRACT16(SHR32(X[j+c*N],shift)),
+ EXTRACT16(SHR32(X[j+c*N],shift)));
+ } while (++j<eBands[i+1]<<LM);
+ } else {
+ do {
+ sum = MAC16_16(sum, EXTRACT16(SHL32(X[j+c*N],-shift)),
+ EXTRACT16(SHL32(X[j+c*N],-shift)));
+ } while (++j<eBands[i+1]<<LM);
+ }
/* We're adding one here to ensure the normalized band isn't larger than unity norm */
bandE[i+c*m->nbEBands] = EPSILON+VSHR32(EXTEND32(celt_sqrt(sum)),-shift);
} else {
@@ -150,16 +155,16 @@ void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, cel
#else /* FIXED_POINT */
/* Compute the amplitude (sqrt energy) in each of the bands */
-void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *bandE, int end, int C, int M)
+void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *bandE, int end, int C, int LM)
{
int i, c, N;
const opus_int16 *eBands = m->eBands;
- N = M*m->shortMdctSize;
+ N = m->shortMdctSize<<LM;
c=0; do {
for (i=0;i<end;i++)
{
opus_val32 sum;
- sum = 1e-27f + celt_inner_prod(&X[c*N+M*eBands[i]], &X[c*N+M*eBands[i]], M*(eBands[i+1]-eBands[i]));
+ sum = 1e-27f + celt_inner_prod(&X[c*N+(eBands[i]<<LM)], &X[c*N+(eBands[i]<<LM)], (eBands[i+1]-eBands[i])<<LM);
bandE[i+c*m->nbEBands] = celt_sqrt(sum);
/*printf ("%f ", bandE[i+c*m->nbEBands]);*/
}
diff --git a/celt/bands.h b/celt/bands.h
index 053ac8a11..e6ad9c524 100644
--- a/celt/bands.h
+++ b/celt/bands.h
@@ -41,7 +41,7 @@
* @param X Spectrum
* @param bandE Square root of the energy for each band (returned)
*/
-void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *bandE, int end, int C, int M);
+void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *bandE, int end, int C, int LM);
/*void compute_noise_energies(const CELTMode *m, const celt_sig *X, const opus_val16 *tonality, celt_ener *bandE);*/
diff --git a/celt/celt_encoder.c b/celt/celt_encoder.c
index 1ac00581a..8a1c7483e 100644
--- a/celt/celt_encoder.c
+++ b/celt/celt_encoder.c
@@ -1519,7 +1519,7 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_val16 * pcm,
if (secondMdct)
{
compute_mdcts(mode, 0, in, freq, C, CC, LM, st->upsample);
- compute_band_energies(mode, freq, bandE, effEnd, C, M);
+ compute_band_energies(mode, freq, bandE, effEnd, C, LM);
amp2Log2(mode, effEnd, end, bandE, bandLogE2, C);
for (i=0;i<C*nbEBands;i++)
bandLogE2[i] += HALF16(SHL16(LM, DB_SHIFT));
@@ -1528,7 +1528,7 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_val16 * pcm,
compute_mdcts(mode, shortBlocks, in, freq, C, CC, LM, st->upsample);
if (CC==2&&C==1)
tf_chan = 0;
- compute_band_energies(mode, freq, bandE, effEnd, C, M);
+ compute_band_energies(mode, freq, bandE, effEnd, C, LM);
if (st->lfe)
{
@@ -1651,7 +1651,7 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_val16 * pcm,
isTransient = 1;
shortBlocks = M;
compute_mdcts(mode, shortBlocks, in, freq, C, CC, LM, st->upsample);
- compute_band_energies(mode, freq, bandE, effEnd, C, M);
+ compute_band_energies(mode, freq, bandE, effEnd, C, LM);
amp2Log2(mode, effEnd, end, bandE, bandLogE, C);
/* Compensate for the scaling of short vs long mdcts */
for (i=0;i<C*nbEBands;i++)
--
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