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Add entropy coding of qext bit allocation
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@jmvalin
jmvalin committed Nov 29, 2024
1 parent debd583 commit d9b1ef8
Showing 1 changed file with 53 additions and 13 deletions.
66 changes: 53 additions & 13 deletions celt/rate.c
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Original file line number Diff line number Diff line change
Expand Up @@ -647,17 +647,58 @@ int clt_compute_allocation(const CELTMode *m, int start, int end, const int *off

#ifdef ENABLE_QEXT

static const unsigned char last_zero[3] = {64, 50, 0};
static const unsigned char last_cap[3] = {110, 60, 0};
static const unsigned char last_other[4] = {120, 112, 70, 0};

static void ec_enc_depth(ec_enc *enc, opus_int32 depth, opus_int32 cap, opus_int32 *last) {
int sym = 3;
if (depth==*last) sym = 2;
if (depth==cap) sym = 1;
if (depth==0) sym = 0;
if (*last == 0) {
ec_enc_icdf(enc, IMIN(sym, 2), last_zero, 7);
} else if (*last == cap) {
ec_enc_icdf(enc, IMIN(sym, 2), last_cap, 7);
} else {
ec_enc_icdf(enc, sym, last_other, 7);
}
/* We accept some redundancy if depth==last (for last different from 0 and cap). */
if (sym == 3) ec_enc_uint(enc, depth-1, cap);
*last = depth;
}

static int ec_dec_depth(ec_dec *dec, opus_int32 cap, opus_int32 *last) {
int depth, sym;
if (*last == 0) {
sym = ec_dec_icdf(dec, last_zero, 7);
if (sym==2) sym=3;
} else if (*last == cap) {
sym = ec_dec_icdf(dec, last_cap, 7);
if (sym==2) sym=3;
} else {
sym = ec_dec_icdf(dec, last_other, 7);
}
if (sym==0) depth=0;
else if (sym==1) depth=cap;
else if (sym==2) depth=*last;
else depth = 1 + ec_dec_uint(dec, cap);
*last = depth;
return depth;
}

void clt_compute_extra_allocation(const CELTMode *m, const CELTMode *qext_mode, int start, int end, const celt_glog *bandLogE, const celt_glog *qext_bandLogE,
opus_int32 total, int *extra_pulses, int *extra_equant, int C, int LM, ec_ctx *ec, int encode)
{
int i;
opus_int32 last=0;
opus_val32 sum;
opus_val32 fill;
int iter;
int tot_bands;
int tot_samples;
VARDECL(int, depth);

VARDECL(opus_int32, cap);
if (qext_mode != NULL) {
celt_assert(start==0);
celt_assert(end==m->nbEBands);
Expand All @@ -667,6 +708,9 @@ void clt_compute_extra_allocation(const CELTMode *m, const CELTMode *qext_mode,
tot_bands = end;
tot_samples = (m->eBands[end]-m->eBands[start])*C<<LM;
}
ALLOC(cap, tot_bands, opus_int32);
for (i=start;i<end;i++) cap[i] = 12;
for (i=0;i<NB_QEXT_BANDS;i++) cap[end+i] = 14;

if (total <= 0) {
for (i=start;i<m->nbEBands+NB_QEXT_BANDS;i++) {
Expand All @@ -678,11 +722,9 @@ void clt_compute_extra_allocation(const CELTMode *m, const CELTMode *qext_mode,
if (encode) {
VARDECL(opus_val16, flatE);
VARDECL(int, Ncoef);
VARDECL(opus_val16, cap);
VARDECL(opus_val16, min);

ALLOC(flatE, tot_bands, opus_val16);
ALLOC(cap, tot_bands, opus_val16);
ALLOC(min, tot_bands, opus_val16);
ALLOC(Ncoef, tot_bands, int);
for (i=start;i<end;i++) {
Expand All @@ -691,7 +733,6 @@ void clt_compute_extra_allocation(const CELTMode *m, const CELTMode *qext_mode,
/* Remove the effect of band width, eMeans and pre-emphasis to compute the real (flat) spectrum. */
for (i=start;i<end;i++) {
flatE[i] = PSHR32(bandLogE[i] - GCONST(0.0625f)*m->logN[i] + SHL32(eMeans[i],DB_SHIFT-4) - GCONST(.0062f)*(i+5)*(i+5), DB_SHIFT-10);
cap[i] = QCONST16(12.f, 10);
min[i] = 0;
}
if (C==2) {
Expand All @@ -707,7 +748,6 @@ void clt_compute_extra_allocation(const CELTMode *m, const CELTMode *qext_mode,
min_depth = QCONST16(1.f, 10);
for (i=0;i<NB_QEXT_BANDS;i++) {
Ncoef[end+i] = (qext_mode->eBands[i+1]-qext_mode->eBands[i])*C<<LM;
cap[end+i] = QCONST16(14.f, 10);
min[end+i] = min_depth;
}
for (i=0;i<NB_QEXT_BANDS;i++) {
Expand All @@ -727,28 +767,28 @@ void clt_compute_extra_allocation(const CELTMode *m, const CELTMode *qext_mode,
}
total >>= BITRES;
fill = (SHL32(total, 10) + sum)/tot_samples;
/* Iteratively refine the fill level considering that we allow between 0 and 12 bits of depth. */
/* Iteratively refine the fill level considering the depth min and cap. */
for (iter=0;iter<10;iter++) {
sum = 0;
for (i=start;i<tot_bands;i++)
sum += Ncoef[i] * MIN32(cap[i], MAX32(min[i], flatE[i]-fill));
sum += Ncoef[i] * MIN32(SHL32(cap[i], 10), MAX32(min[i], flatE[i]-fill));
fill -= (SHL32(total, 10) - sum)/tot_samples;
}
for (i=start;i<tot_bands;i++) {
#ifdef FIXED_POINT
depth[i] = PSHR32(MIN32(cap[i], MAX32(min[i], flatE[i]-fill)), 10-2);
depth[i] = PSHR32(MIN32(SHL32(cap[i], 10), MAX32(min[i], flatE[i]-fill)), 10-2);
#else
depth[i] = (int)floor(.5+4*MIN32(cap[i], MAX32(min[i], flatE[i]-fill)));
depth[i] = (int)floor(.5+4*MIN32(SHL32(cap[i], 10), MAX32(min[i], flatE[i]-fill)));
#endif
if (ec_tell_frac(ec) + 47 < ec->storage*8<<BITRES)
ec_enc_uint(ec, depth[i], 57);
if (ec_tell_frac(ec) + 80 < ec->storage*8<<BITRES)
ec_enc_depth(ec, depth[i], 4*cap[i], &last);
else
depth[i] = 0;
}
} else {
for (i=start;i<tot_bands;i++) {
if (ec_tell_frac(ec) + 47 < ec->storage*8<<BITRES)
depth[i] = ec_dec_uint(ec, 57);
if (ec_tell_frac(ec) + 80 < ec->storage*8<<BITRES)
depth[i] = ec_dec_depth(ec, 4*cap[i], &last);
else
depth[i] = 0;
}
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