comparison src/opus-1.3/celt/bands.c @ 154:4664ac0c1032

Add Opus sources and macOS builds

+/* Copyright (c) 2007-2008 CSIRO
+   Copyright (c) 2007-2009 Xiph.Org Foundation
+   Copyright (c) 2008-2009 Gregory Maxwell
+   Written by Jean-Marc Valin and Gregory Maxwell */
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <math.h>
+#include "bands.h"
+#include "modes.h"
+#include "vq.h"
+#include "cwrs.h"
+#include "stack_alloc.h"
+#include "os_support.h"
+#include "mathops.h"
+#include "rate.h"
+#include "quant_bands.h"
+#include "pitch.h"
+
+int hysteresis_decision(opus_val16 val, const opus_val16 *thresholds, const opus_val16 *hysteresis, int N, int prev)
+{
+   int i;
+   for (i=0;i<N;i++)
+   {
+      if (val < thresholds[i])
+         break;
+   }
+   if (i>prev && val < thresholds[prev]+hysteresis[prev])
+      i=prev;
+   if (i<prev && val > thresholds[prev-1]-hysteresis[prev-1])
+      i=prev;
+   return i;
+}
+
+opus_uint32 celt_lcg_rand(opus_uint32 seed)
+{
+   return 1664525 * seed + 1013904223;
+}
+
+/* This is a cos() approximation designed to be bit-exact on any platform. Bit exactness
+   with this approximation is important because it has an impact on the bit allocation */
+opus_int16 bitexact_cos(opus_int16 x)
+{
+   opus_int32 tmp;
+   opus_int16 x2;
+   tmp = (4096+((opus_int32)(x)*(x)))>>13;
+   celt_sig_assert(tmp<=32767);
+   x2 = tmp;
+   x2 = (32767-x2) + FRAC_MUL16(x2, (-7651 + FRAC_MUL16(x2, (8277 + FRAC_MUL16(-626, x2)))));
+   celt_sig_assert(x2<=32766);
+   return 1+x2;
+}
+
+int bitexact_log2tan(int isin,int icos)
+{
+   int lc;
+   int ls;
+   lc=EC_ILOG(icos);
+   ls=EC_ILOG(isin);
+   icos<<=15-lc;
+   isin<<=15-ls;
+   return (ls-lc)*(1<<11)
+         +FRAC_MUL16(isin, FRAC_MUL16(isin, -2597) + 7932)
+         -FRAC_MUL16(icos, FRAC_MUL16(icos, -2597) + 7932);
+}
+
+#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 LM, int arch)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   (void)arch;
+   N = m->shortMdctSize<<LM;
+   c=0; do {
+      for (i=0;i<end;i++)
+      {
+         int j;
+         opus_val32 maxval=0;
+         opus_val32 sum = 0;
+
+         maxval = celt_maxabs32(&X[c*N+(eBands[i]<<LM)], (eBands[i+1]-eBands[i])<<LM);
+         if (maxval > 0)
+         {
+            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 {
+            bandE[i+c*m->nbEBands] = EPSILON;
+         }
+         /*printf ("%f ", bandE[i+c*m->nbEBands]);*/
+      }
+   } while (++c<C);
+   /*printf ("\n");*/
+}
+
+/* Normalise each band such that the energy is one. */
+void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, celt_norm * OPUS_RESTRICT X, const celt_ener *bandE, int end, int C, int M)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   N = M*m->shortMdctSize;
+   c=0; do {
+      i=0; do {
+         opus_val16 g;
+         int j,shift;
+         opus_val16 E;
+         shift = celt_zlog2(bandE[i+c*m->nbEBands])-13;
+         E = VSHR32(bandE[i+c*m->nbEBands], shift);
+         g = EXTRACT16(celt_rcp(SHL32(E,3)));
+         j=M*eBands[i]; do {
+            X[j+c*N] = MULT16_16_Q15(VSHR32(freq[j+c*N],shift-1),g);
+         } while (++j<M*eBands[i+1]);
+      } while (++i<end);
+   } while (++c<C);
+}
+
+#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 LM, int arch)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   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+(eBands[i]<<LM)], &X[c*N+(eBands[i]<<LM)], (eBands[i+1]-eBands[i])<<LM, arch);
+         bandE[i+c*m->nbEBands] = celt_sqrt(sum);
+         /*printf ("%f ", bandE[i+c*m->nbEBands]);*/
+      }
+   } while (++c<C);
+   /*printf ("\n");*/
+}
+
+/* Normalise each band such that the energy is one. */
+void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, celt_norm * OPUS_RESTRICT X, const celt_ener *bandE, int end, int C, int M)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   N = M*m->shortMdctSize;
+   c=0; do {
+      for (i=0;i<end;i++)
+      {
+         int j;
+         opus_val16 g = 1.f/(1e-27f+bandE[i+c*m->nbEBands]);
+         for (j=M*eBands[i];j<M*eBands[i+1];j++)
+            X[j+c*N] = freq[j+c*N]*g;
+      }
+   } while (++c<C);
+}
+
+#endif /* FIXED_POINT */
+
+/* De-normalise the energy to produce the synthesis from the unit-energy bands */
+void denormalise_bands(const CELTMode *m, const celt_norm * OPUS_RESTRICT X,
+      celt_sig * OPUS_RESTRICT freq, const opus_val16 *bandLogE, int start,
+      int end, int M, int downsample, int silence)
+{
+   int i, N;
+   int bound;
+   celt_sig * OPUS_RESTRICT f;
+   const celt_norm * OPUS_RESTRICT x;
+   const opus_int16 *eBands = m->eBands;
+   N = M*m->shortMdctSize;
+   bound = M*eBands[end];
+   if (downsample!=1)
+      bound = IMIN(bound, N/downsample);
+   if (silence)
+   {
+      bound = 0;
+      start = end = 0;
+   }
+   f = freq;
+   x = X+M*eBands[start];
+   for (i=0;i<M*eBands[start];i++)
+      *f++ = 0;
+   for (i=start;i<end;i++)
+   {
+      int j, band_end;
+      opus_val16 g;
+      opus_val16 lg;
+#ifdef FIXED_POINT
+      int shift;
+#endif
+      j=M*eBands[i];
+      band_end = M*eBands[i+1];
+      lg = SATURATE16(ADD32(bandLogE[i], SHL32((opus_val32)eMeans[i],6)));
+#ifndef FIXED_POINT
+      g = celt_exp2(MIN32(32.f, lg));
+#else
+      /* Handle the integer part of the log energy */
+      shift = 16-(lg>>DB_SHIFT);
+      if (shift>31)
+      {
+         shift=0;
+         g=0;
+      } else {
+         /* Handle the fractional part. */
+         g = celt_exp2_frac(lg&((1<<DB_SHIFT)-1));
+      }
+      /* Handle extreme gains with negative shift. */
+      if (shift<0)
+      {
+         /* For shift <= -2 and g > 16384 we'd be likely to overflow, so we're
+            capping the gain here, which is equivalent to a cap of 18 on lg.
+            This shouldn't trigger unless the bitstream is already corrupted. */
+         if (shift <= -2)
+         {
+            g = 16384;
+            shift = -2;
+         }
+         do {
+            *f++ = SHL32(MULT16_16(*x++, g), -shift);
+         } while (++j<band_end);
+      } else
+#endif
+         /* Be careful of the fixed-point "else" just above when changing this code */
+         do {
+            *f++ = SHR32(MULT16_16(*x++, g), shift);
+         } while (++j<band_end);
+   }
+   celt_assert(start <= end);
+   OPUS_CLEAR(&freq[bound], N-bound);
+}
+
+/* This prevents energy collapse for transients with multiple short MDCTs */
+void anti_collapse(const CELTMode *m, celt_norm *X_, unsigned char *collapse_masks, int LM, int C, int size,
+      int start, int end, const opus_val16 *logE, const opus_val16 *prev1logE,
+      const opus_val16 *prev2logE, const int *pulses, opus_uint32 seed, int arch)
+{
+   int c, i, j, k;
+   for (i=start;i<end;i++)
+   {
+      int N0;
+      opus_val16 thresh, sqrt_1;
+      int depth;
+#ifdef FIXED_POINT
+      int shift;
+      opus_val32 thresh32;
+#endif
+
+      N0 = m->eBands[i+1]-m->eBands[i];
+      /* depth in 1/8 bits */
+      celt_sig_assert(pulses[i]>=0);
+      depth = celt_udiv(1+pulses[i], (m->eBands[i+1]-m->eBands[i]))>>LM;
+
+#ifdef FIXED_POINT
+      thresh32 = SHR32(celt_exp2(-SHL16(depth, 10-BITRES)),1);
+      thresh = MULT16_32_Q15(QCONST16(0.5f, 15), MIN32(32767,thresh32));
+      {
+         opus_val32 t;
+         t = N0<<LM;
+         shift = celt_ilog2(t)>>1;
+         t = SHL32(t, (7-shift)<<1);
+         sqrt_1 = celt_rsqrt_norm(t);
+      }
+#else
+      thresh = .5f*celt_exp2(-.125f*depth);
+      sqrt_1 = celt_rsqrt(N0<<LM);
+#endif
+
+      c=0; do
+      {
+         celt_norm *X;
+         opus_val16 prev1;
+         opus_val16 prev2;
+         opus_val32 Ediff;
+         opus_val16 r;
+         int renormalize=0;
+         prev1 = prev1logE[c*m->nbEBands+i];
+         prev2 = prev2logE[c*m->nbEBands+i];
+         if (C==1)
+         {
+            prev1 = MAX16(prev1,prev1logE[m->nbEBands+i]);
+            prev2 = MAX16(prev2,prev2logE[m->nbEBands+i]);
+         }
+         Ediff = EXTEND32(logE[c*m->nbEBands+i])-EXTEND32(MIN16(prev1,prev2));
+         Ediff = MAX32(0, Ediff);
+
+#ifdef FIXED_POINT
+         if (Ediff < 16384)
+         {
+            opus_val32 r32 = SHR32(celt_exp2(-EXTRACT16(Ediff)),1);
+            r = 2*MIN16(16383,r32);
+         } else {
+            r = 0;
+         }
+         if (LM==3)
+            r = MULT16_16_Q14(23170, MIN32(23169, r));
+         r = SHR16(MIN16(thresh, r),1);
+         r = SHR32(MULT16_16_Q15(sqrt_1, r),shift);
+#else
+         /* r needs to be multiplied by 2 or 2*sqrt(2) depending on LM because
+            short blocks don't have the same energy as long */
+         r = 2.f*celt_exp2(-Ediff);
+         if (LM==3)
+            r *= 1.41421356f;
+         r = MIN16(thresh, r);
+         r = r*sqrt_1;
+#endif
+         X = X_+c*size+(m->eBands[i]<<LM);
+         for (k=0;k<1<<LM;k++)
+         {
+            /* Detect collapse */
+            if (!(collapse_masks[i*C+c]&1<<k))
+            {
+               /* Fill with noise */
+               for (j=0;j<N0;j++)
+               {
+                  seed = celt_lcg_rand(seed);
+                  X[(j<<LM)+k] = (seed&0x8000 ? r : -r);
+               }
+               renormalize = 1;
+            }
+         }
+         /* We just added some energy, so we need to renormalise */
+         if (renormalize)
+            renormalise_vector(X, N0<<LM, Q15ONE, arch);
+      } while (++c<C);
+   }
+}
+
+/* Compute the weights to use for optimizing normalized distortion across
+   channels. We use the amplitude to weight square distortion, which means
+   that we use the square root of the value we would have been using if we
+   wanted to minimize the MSE in the non-normalized domain. This roughly
+   corresponds to some quick-and-dirty perceptual experiments I ran to
+   measure inter-aural masking (there doesn't seem to be any published data
+   on the topic). */
+static void compute_channel_weights(celt_ener Ex, celt_ener Ey, opus_val16 w[2])
+{
+   celt_ener minE;
+#if FIXED_POINT
+   int shift;
+#endif
+   minE = MIN32(Ex, Ey);
+   /* Adjustment to make the weights a bit more conservative. */
+   Ex = ADD32(Ex, minE/3);
+   Ey = ADD32(Ey, minE/3);
+#if FIXED_POINT
+   shift = celt_ilog2(EPSILON+MAX32(Ex, Ey))-14;
+#endif
+   w[0] = VSHR32(Ex, shift);
+   w[1] = VSHR32(Ey, shift);
+}
+
+static void intensity_stereo(const CELTMode *m, celt_norm * OPUS_RESTRICT X, const celt_norm * OPUS_RESTRICT Y, const celt_ener *bandE, int bandID, int N)
+{
+   int i = bandID;
+   int j;
+   opus_val16 a1, a2;
+   opus_val16 left, right;
+   opus_val16 norm;
+#ifdef FIXED_POINT
+   int shift = celt_zlog2(MAX32(bandE[i], bandE[i+m->nbEBands]))-13;
+#endif
+   left = VSHR32(bandE[i],shift);
+   right = VSHR32(bandE[i+m->nbEBands],shift);
+   norm = EPSILON + celt_sqrt(EPSILON+MULT16_16(left,left)+MULT16_16(right,right));
+   a1 = DIV32_16(SHL32(EXTEND32(left),14),norm);
+   a2 = DIV32_16(SHL32(EXTEND32(right),14),norm);
+   for (j=0;j<N;j++)
+   {
+      celt_norm r, l;
+      l = X[j];
+      r = Y[j];
+      X[j] = EXTRACT16(SHR32(MAC16_16(MULT16_16(a1, l), a2, r), 14));
+      /* Side is not encoded, no need to calculate */
+   }
+}
+
+static void stereo_split(celt_norm * OPUS_RESTRICT X, celt_norm * OPUS_RESTRICT Y, int N)
+{
+   int j;
+   for (j=0;j<N;j++)
+   {
+      opus_val32 r, l;
+      l = MULT16_16(QCONST16(.70710678f, 15), X[j]);
+      r = MULT16_16(QCONST16(.70710678f, 15), Y[j]);
+      X[j] = EXTRACT16(SHR32(ADD32(l, r), 15));
+      Y[j] = EXTRACT16(SHR32(SUB32(r, l), 15));
+   }
+}
+
+static void stereo_merge(celt_norm * OPUS_RESTRICT X, celt_norm * OPUS_RESTRICT Y, opus_val16 mid, int N, int arch)
+{
+   int j;
+   opus_val32 xp=0, side=0;
+   opus_val32 El, Er;
+   opus_val16 mid2;
+#ifdef FIXED_POINT
+   int kl, kr;
+#endif
+   opus_val32 t, lgain, rgain;
+
+   /* Compute the norm of X+Y and X-Y as |X|^2 + |Y|^2 +/- sum(xy) */
+   dual_inner_prod(Y, X, Y, N, &xp, &side, arch);
+   /* Compensating for the mid normalization */
+   xp = MULT16_32_Q15(mid, xp);
+   /* mid and side are in Q15, not Q14 like X and Y */
+   mid2 = SHR16(mid, 1);
+   El = MULT16_16(mid2, mid2) + side - 2*xp;
+   Er = MULT16_16(mid2, mid2) + side + 2*xp;
+   if (Er < QCONST32(6e-4f, 28) || El < QCONST32(6e-4f, 28))
+   {
+      OPUS_COPY(Y, X, N);
+      return;
+   }
+
+#ifdef FIXED_POINT
+   kl = celt_ilog2(El)>>1;
+   kr = celt_ilog2(Er)>>1;
+#endif
+   t = VSHR32(El, (kl-7)<<1);
+   lgain = celt_rsqrt_norm(t);
+   t = VSHR32(Er, (kr-7)<<1);
+   rgain = celt_rsqrt_norm(t);
+
+#ifdef FIXED_POINT
+   if (kl < 7)
+      kl = 7;
+   if (kr < 7)
+      kr = 7;
+#endif
+
+   for (j=0;j<N;j++)
+   {
+      celt_norm r, l;
+      /* Apply mid scaling (side is already scaled) */
+      l = MULT16_16_P15(mid, X[j]);
+      r = Y[j];
+      X[j] = EXTRACT16(PSHR32(MULT16_16(lgain, SUB16(l,r)), kl+1));
+      Y[j] = EXTRACT16(PSHR32(MULT16_16(rgain, ADD16(l,r)), kr+1));
+   }
+}
+
+/* Decide whether we should spread the pulses in the current frame */
+int spreading_decision(const CELTMode *m, const celt_norm *X, int *average,
+      int last_decision, int *hf_average, int *tapset_decision, int update_hf,
+      int end, int C, int M, const int *spread_weight)
+{
+   int i, c, N0;
+   int sum = 0, nbBands=0;
+   const opus_int16 * OPUS_RESTRICT eBands = m->eBands;
+   int decision;
+   int hf_sum=0;
+
+   celt_assert(end>0);
+
+   N0 = M*m->shortMdctSize;
+
+   if (M*(eBands[end]-eBands[end-1]) <= 8)
+      return SPREAD_NONE;
+   c=0; do {
+      for (i=0;i<end;i++)
+      {
+         int j, N, tmp=0;
+         int tcount[3] = {0,0,0};
+         const celt_norm * OPUS_RESTRICT x = X+M*eBands[i]+c*N0;
+         N = M*(eBands[i+1]-eBands[i]);
+         if (N<=8)
+            continue;
+         /* Compute rough CDF of |x[j]| */
+         for (j=0;j<N;j++)
+         {
+            opus_val32 x2N; /* Q13 */
+
+            x2N = MULT16_16(MULT16_16_Q15(x[j], x[j]), N);
+            if (x2N < QCONST16(0.25f,13))
+               tcount[0]++;
+            if (x2N < QCONST16(0.0625f,13))
+               tcount[1]++;
+            if (x2N < QCONST16(0.015625f,13))
+               tcount[2]++;
+         }
+
+         /* Only include four last bands (8 kHz and up) */
+         if (i>m->nbEBands-4)
+            hf_sum += celt_udiv(32*(tcount[1]+tcount[0]), N);
+         tmp = (2*tcount[2] >= N) + (2*tcount[1] >= N) + (2*tcount[0] >= N);
+         sum += tmp*spread_weight[i];
+         nbBands+=spread_weight[i];
+      }
+   } while (++c<C);
+
+   if (update_hf)
+   {
+      if (hf_sum)
+         hf_sum = celt_udiv(hf_sum, C*(4-m->nbEBands+end));
+      *hf_average = (*hf_average+hf_sum)>>1;
+      hf_sum = *hf_average;
+      if (*tapset_decision==2)
+         hf_sum += 4;
+      else if (*tapset_decision==0)
+         hf_sum -= 4;
+      if (hf_sum > 22)
+         *tapset_decision=2;
+      else if (hf_sum > 18)
+         *tapset_decision=1;
+      else
+         *tapset_decision=0;
+   }
+   /*printf("%d %d %d\n", hf_sum, *hf_average, *tapset_decision);*/
+   celt_assert(nbBands>0); /* end has to be non-zero */
+   celt_assert(sum>=0);
+   sum = celt_udiv((opus_int32)sum<<8, nbBands);
+   /* Recursive averaging */
+   sum = (sum+*average)>>1;
+   *average = sum;
+   /* Hysteresis */
+   sum = (3*sum + (((3-last_decision)<<7) + 64) + 2)>>2;
+   if (sum < 80)
+   {
+      decision = SPREAD_AGGRESSIVE;
+   } else if (sum < 256)
+   {
+      decision = SPREAD_NORMAL;
+   } else if (sum < 384)
+   {
+      decision = SPREAD_LIGHT;
+   } else {
+      decision = SPREAD_NONE;
+   }
+#ifdef FUZZING
+   decision = rand()&0x3;
+   *tapset_decision=rand()%3;
+#endif
+   return decision;
+}
+
+/* Indexing table for converting from natural Hadamard to ordery Hadamard
+   This is essentially a bit-reversed Gray, on top of which we've added
+   an inversion of the order because we want the DC at the end rather than
+   the beginning. The lines are for N=2, 4, 8, 16 */
+static const int ordery_table[] = {
+       1,  0,
+       3,  0,  2,  1,
+       7,  0,  4,  3,  6,  1,  5,  2,
+      15,  0,  8,  7, 12,  3, 11,  4, 14,  1,  9,  6, 13,  2, 10,  5,
+};
+
+static void deinterleave_hadamard(celt_norm *X, int N0, int stride, int hadamard)
+{
+   int i,j;
+   VARDECL(celt_norm, tmp);
+   int N;
+   SAVE_STACK;
+   N = N0*stride;
+   ALLOC(tmp, N, celt_norm);
+   celt_assert(stride>0);
+   if (hadamard)
+   {
+      const int *ordery = ordery_table+stride-2;
+      for (i=0;i<stride;i++)
+      {
+         for (j=0;j<N0;j++)
+            tmp[ordery[i]*N0+j] = X[j*stride+i];
+      }
+   } else {
+      for (i=0;i<stride;i++)
+         for (j=0;j<N0;j++)
+            tmp[i*N0+j] = X[j*stride+i];
+   }
+   OPUS_COPY(X, tmp, N);
+   RESTORE_STACK;
+}
+
+static void interleave_hadamard(celt_norm *X, int N0, int stride, int hadamard)
+{
+   int i,j;
+   VARDECL(celt_norm, tmp);
+   int N;
+   SAVE_STACK;
+   N = N0*stride;
+   ALLOC(tmp, N, celt_norm);
+   if (hadamard)
+   {
+      const int *ordery = ordery_table+stride-2;
+      for (i=0;i<stride;i++)
+         for (j=0;j<N0;j++)
+            tmp[j*stride+i] = X[ordery[i]*N0+j];
+   } else {
+      for (i=0;i<stride;i++)
+         for (j=0;j<N0;j++)
+            tmp[j*stride+i] = X[i*N0+j];
+   }
+   OPUS_COPY(X, tmp, N);
+   RESTORE_STACK;
+}
+
+void haar1(celt_norm *X, int N0, int stride)
+{
+   int i, j;
+   N0 >>= 1;
+   for (i=0;i<stride;i++)
+      for (j=0;j<N0;j++)
+      {
+         opus_val32 tmp1, tmp2;
+         tmp1 = MULT16_16(QCONST16(.70710678f,15), X[stride*2*j+i]);
+         tmp2 = MULT16_16(QCONST16(.70710678f,15), X[stride*(2*j+1)+i]);
+         X[stride*2*j+i] = EXTRACT16(PSHR32(ADD32(tmp1, tmp2), 15));
+         X[stride*(2*j+1)+i] = EXTRACT16(PSHR32(SUB32(tmp1, tmp2), 15));
+      }
+}
+
+static int compute_qn(int N, int b, int offset, int pulse_cap, int stereo)
+{
+   static const opus_int16 exp2_table8[8] =
+      {16384, 17866, 19483, 21247, 23170, 25267, 27554, 30048};
+   int qn, qb;
+   int N2 = 2*N-1;
+   if (stereo && N==2)
+      N2--;
+   /* The upper limit ensures that in a stereo split with itheta==16384, we'll
+       always have enough bits left over to code at least one pulse in the
+       side; otherwise it would collapse, since it doesn't get folded. */
+   qb = celt_sudiv(b+N2*offset, N2);
+   qb = IMIN(b-pulse_cap-(4<<BITRES), qb);
+
+   qb = IMIN(8<<BITRES, qb);
+
+   if (qb<(1<<BITRES>>1)) {
+      qn = 1;
+   } else {
+      qn = exp2_table8[qb&0x7]>>(14-(qb>>BITRES));
+      qn = (qn+1)>>1<<1;
+   }
+   celt_assert(qn <= 256);
+   return qn;
+}
+
+struct band_ctx {
+   int encode;
+   int resynth;
+   const CELTMode *m;
+   int i;
+   int intensity;
+   int spread;
+   int tf_change;
+   ec_ctx *ec;
+   opus_int32 remaining_bits;
+   const celt_ener *bandE;
+   opus_uint32 seed;
+   int arch;
+   int theta_round;
+   int disable_inv;
+   int avoid_split_noise;
+};
+
+struct split_ctx {
+   int inv;
+   int imid;
+   int iside;
+   int delta;
+   int itheta;
+   int qalloc;
+};
+
+static void compute_theta(struct band_ctx *ctx, struct split_ctx *sctx,
+      celt_norm *X, celt_norm *Y, int N, int *b, int B, int B0,
+      int LM,
+      int stereo, int *fill)
+{
+   int qn;
+   int itheta=0;
+   int delta;
+   int imid, iside;
+   int qalloc;
+   int pulse_cap;
+   int offset;
+   opus_int32 tell;
+   int inv=0;
+   int encode;
+   const CELTMode *m;
+   int i;
+   int intensity;
+   ec_ctx *ec;
+   const celt_ener *bandE;
+
+   encode = ctx->encode;
+   m = ctx->m;
+   i = ctx->i;
+   intensity = ctx->intensity;
+   ec = ctx->ec;
+   bandE = ctx->bandE;
+
+   /* Decide on the resolution to give to the split parameter theta */
+   pulse_cap = m->logN[i]+LM*(1<<BITRES);
+   offset = (pulse_cap>>1) - (stereo&&N==2 ? QTHETA_OFFSET_TWOPHASE : QTHETA_OFFSET);
+   qn = compute_qn(N, *b, offset, pulse_cap, stereo);
+   if (stereo && i>=intensity)
+      qn = 1;
+   if (encode)
+   {
+      /* theta is the atan() of the ratio between the (normalized)
+         side and mid. With just that parameter, we can re-scale both
+         mid and side because we know that 1) they have unit norm and
+         2) they are orthogonal. */
+      itheta = stereo_itheta(X, Y, stereo, N, ctx->arch);
+   }
+   tell = ec_tell_frac(ec);
+   if (qn!=1)
+   {
+      if (encode)
+      {
+         if (!stereo || ctx->theta_round == 0)
+         {
+            itheta = (itheta*(opus_int32)qn+8192)>>14;
+            if (!stereo && ctx->avoid_split_noise && itheta > 0 && itheta < qn)
+            {
+               /* Check if the selected value of theta will cause the bit allocation
+                  to inject noise on one side. If so, make sure the energy of that side
+                  is zero. */
+               int unquantized = celt_udiv((opus_int32)itheta*16384, qn);
+               imid = bitexact_cos((opus_int16)unquantized);
+               iside = bitexact_cos((opus_int16)(16384-unquantized));
+               delta = FRAC_MUL16((N-1)<<7,bitexact_log2tan(iside,imid));
+               if (delta > *b)
+                  itheta = qn;
+               else if (delta < -*b)
+                  itheta = 0;
+            }
+         } else {
+            int down;
+            /* Bias quantization towards itheta=0 and itheta=16384. */
+            int bias = itheta > 8192 ? 32767/qn : -32767/qn;
+            down = IMIN(qn-1, IMAX(0, (itheta*(opus_int32)qn + bias)>>14));
+            if (ctx->theta_round < 0)
+               itheta = down;
+            else
+               itheta = down+1;
+         }
+      }
+      /* Entropy coding of the angle. We use a uniform pdf for the
+         time split, a step for stereo, and a triangular one for the rest. */
+      if (stereo && N>2)
+      {
+         int p0 = 3;
+         int x = itheta;
+         int x0 = qn/2;
+         int ft = p0*(x0+1) + x0;
+         /* Use a probability of p0 up to itheta=8192 and then use 1 after */
+         if (encode)
+         {
+            ec_encode(ec,x<=x0?p0*x:(x-1-x0)+(x0+1)*p0,x<=x0?p0*(x+1):(x-x0)+(x0+1)*p0,ft);
+         } else {
+            int fs;
+            fs=ec_decode(ec,ft);
+            if (fs<(x0+1)*p0)
+               x=fs/p0;
+            else
+               x=x0+1+(fs-(x0+1)*p0);
+            ec_dec_update(ec,x<=x0?p0*x:(x-1-x0)+(x0+1)*p0,x<=x0?p0*(x+1):(x-x0)+(x0+1)*p0,ft);
+            itheta = x;
+         }
+      } else if (B0>1 || stereo) {
+         /* Uniform pdf */
+         if (encode)
+            ec_enc_uint(ec, itheta, qn+1);
+         else
+            itheta = ec_dec_uint(ec, qn+1);
+      } else {
+         int fs=1, ft;
+         ft = ((qn>>1)+1)*((qn>>1)+1);
+         if (encode)
+         {
+            int fl;
+
+            fs = itheta <= (qn>>1) ? itheta + 1 : qn + 1 - itheta;
+            fl = itheta <= (qn>>1) ? itheta*(itheta + 1)>>1 :
+             ft - ((qn + 1 - itheta)*(qn + 2 - itheta)>>1);
+
+            ec_encode(ec, fl, fl+fs, ft);
+         } else {
+            /* Triangular pdf */
+            int fl=0;
+            int fm;
+            fm = ec_decode(ec, ft);
+
+            if (fm < ((qn>>1)*((qn>>1) + 1)>>1))
+            {
+               itheta = (isqrt32(8*(opus_uint32)fm + 1) - 1)>>1;
+               fs = itheta + 1;
+               fl = itheta*(itheta + 1)>>1;
+            }
+            else
+            {
+               itheta = (2*(qn + 1)
+                - isqrt32(8*(opus_uint32)(ft - fm - 1) + 1))>>1;
+               fs = qn + 1 - itheta;
+               fl = ft - ((qn + 1 - itheta)*(qn + 2 - itheta)>>1);
+            }
+
+            ec_dec_update(ec, fl, fl+fs, ft);
+         }
+      }
+      celt_assert(itheta>=0);
+      itheta = celt_udiv((opus_int32)itheta*16384, qn);
+      if (encode && stereo)
+      {
+         if (itheta==0)
+            intensity_stereo(m, X, Y, bandE, i, N);
+         else
+            stereo_split(X, Y, N);
+      }
+      /* NOTE: Renormalising X and Y *may* help fixed-point a bit at very high rate.
+               Let's do that at higher complexity */
+   } else if (stereo) {
+      if (encode)
+      {
+         inv = itheta > 8192 && !ctx->disable_inv;
+         if (inv)
+         {
+            int j;
+            for (j=0;j<N;j++)
+               Y[j] = -Y[j];
+         }
+         intensity_stereo(m, X, Y, bandE, i, N);
+      }
+      if (*b>2<<BITRES && ctx->remaining_bits > 2<<BITRES)
+      {
+         if (encode)
+            ec_enc_bit_logp(ec, inv, 2);
+         else
+            inv = ec_dec_bit_logp(ec, 2);
+      } else
+         inv = 0;
+      /* inv flag override to avoid problems with downmixing. */
+      if (ctx->disable_inv)
+         inv = 0;
+      itheta = 0;
+   }
+   qalloc = ec_tell_frac(ec) - tell;
+   *b -= qalloc;
+
+   if (itheta == 0)
+   {
+      imid = 32767;
+      iside = 0;
+      *fill &= (1<<B)-1;
+      delta = -16384;
+   } else if (itheta == 16384)
+   {
+      imid = 0;
+      iside = 32767;
+      *fill &= ((1<<B)-1)<<B;
+      delta = 16384;
+   } else {
+      imid = bitexact_cos((opus_int16)itheta);
+      iside = bitexact_cos((opus_int16)(16384-itheta));
+      /* This is the mid vs side allocation that minimizes squared error
+         in that band. */
+      delta = FRAC_MUL16((N-1)<<7,bitexact_log2tan(iside,imid));
+   }
+
+   sctx->inv = inv;
+   sctx->imid = imid;
+   sctx->iside = iside;
+   sctx->delta = delta;
+   sctx->itheta = itheta;
+   sctx->qalloc = qalloc;
+}
+static unsigned quant_band_n1(struct band_ctx *ctx, celt_norm *X, celt_norm *Y, int b,
+      celt_norm *lowband_out)
+{
+   int c;
+   int stereo;
+   celt_norm *x = X;
+   int encode;
+   ec_ctx *ec;
+
+   encode = ctx->encode;
+   ec = ctx->ec;
+
+   stereo = Y != NULL;
+   c=0; do {
+      int sign=0;
+      if (ctx->remaining_bits>=1<<BITRES)
+      {
+         if (encode)
+         {
+            sign = x[0]<0;
+            ec_enc_bits(ec, sign, 1);
+         } else {
+            sign = ec_dec_bits(ec, 1);
+         }
+         ctx->remaining_bits -= 1<<BITRES;
+         b-=1<<BITRES;
+      }
+      if (ctx->resynth)
+         x[0] = sign ? -NORM_SCALING : NORM_SCALING;
+      x = Y;
+   } while (++c<1+stereo);
+   if (lowband_out)
+      lowband_out[0] = SHR16(X[0],4);
+   return 1;
+}
+
+/* This function is responsible for encoding and decoding a mono partition.
+   It can split the band in two and transmit the energy difference with
+   the two half-bands. It can be called recursively so bands can end up being
+   split in 8 parts. */
+static unsigned quant_partition(struct band_ctx *ctx, celt_norm *X,
+      int N, int b, int B, celt_norm *lowband,
+      int LM,
+      opus_val16 gain, int fill)
+{
+   const unsigned char *cache;
+   int q;
+   int curr_bits;
+   int imid=0, iside=0;
+   int B0=B;
+   opus_val16 mid=0, side=0;
+   unsigned cm=0;
+   celt_norm *Y=NULL;
+   int encode;
+   const CELTMode *m;
+   int i;
+   int spread;
+   ec_ctx *ec;
+
+   encode = ctx->encode;
+   m = ctx->m;
+   i = ctx->i;
+   spread = ctx->spread;
+   ec = ctx->ec;
+
+   /* If we need 1.5 more bit than we can produce, split the band in two. */
+   cache = m->cache.bits + m->cache.index[(LM+1)*m->nbEBands+i];
+   if (LM != -1 && b > cache[cache[0]]+12 && N>2)
+   {
+      int mbits, sbits, delta;
+      int itheta;
+      int qalloc;
+      struct split_ctx sctx;
+      celt_norm *next_lowband2=NULL;
+      opus_int32 rebalance;
+
+      N >>= 1;
+      Y = X+N;
+      LM -= 1;
+      if (B==1)
+         fill = (fill&1)|(fill<<1);
+      B = (B+1)>>1;
+
+      compute_theta(ctx, &sctx, X, Y, N, &b, B, B0, LM, 0, &fill);
+      imid = sctx.imid;
+      iside = sctx.iside;
+      delta = sctx.delta;
+      itheta = sctx.itheta;
+      qalloc = sctx.qalloc;
+#ifdef FIXED_POINT
+      mid = imid;
+      side = iside;
+#else
+      mid = (1.f/32768)*imid;
+      side = (1.f/32768)*iside;
+#endif
+
+      /* Give more bits to low-energy MDCTs than they would otherwise deserve */
+      if (B0>1 && (itheta&0x3fff))
+      {
+         if (itheta > 8192)
+            /* Rough approximation for pre-echo masking */
+            delta -= delta>>(4-LM);
+         else
+            /* Corresponds to a forward-masking slope of 1.5 dB per 10 ms */
+            delta = IMIN(0, delta + (N<<BITRES>>(5-LM)));
+      }
+      mbits = IMAX(0, IMIN(b, (b-delta)/2));
+      sbits = b-mbits;
+      ctx->remaining_bits -= qalloc;
+
+      if (lowband)
+         next_lowband2 = lowband+N; /* >32-bit split case */
+
+      rebalance = ctx->remaining_bits;
+      if (mbits >= sbits)
+      {
+         cm = quant_partition(ctx, X, N, mbits, B, lowband, LM,
+               MULT16_16_P15(gain,mid), fill);
+         rebalance = mbits - (rebalance-ctx->remaining_bits);
+         if (rebalance > 3<<BITRES && itheta!=0)
+            sbits += rebalance - (3<<BITRES);
+         cm |= quant_partition(ctx, Y, N, sbits, B, next_lowband2, LM,
+               MULT16_16_P15(gain,side), fill>>B)<<(B0>>1);
+      } else {
+         cm = quant_partition(ctx, Y, N, sbits, B, next_lowband2, LM,
+               MULT16_16_P15(gain,side), fill>>B)<<(B0>>1);
+         rebalance = sbits - (rebalance-ctx->remaining_bits);
+         if (rebalance > 3<<BITRES && itheta!=16384)
+            mbits += rebalance - (3<<BITRES);
+         cm |= quant_partition(ctx, X, N, mbits, B, lowband, LM,
+               MULT16_16_P15(gain,mid), fill);
+      }
+   } else {
+      /* This is the basic no-split case */
+      q = bits2pulses(m, i, LM, b);
+      curr_bits = pulses2bits(m, i, LM, q);
+      ctx->remaining_bits -= curr_bits;
+
+      /* Ensures we can never bust the budget */
+      while (ctx->remaining_bits < 0 && q > 0)
+      {
+         ctx->remaining_bits += curr_bits;
+         q--;
+         curr_bits = pulses2bits(m, i, LM, q);
+         ctx->remaining_bits -= curr_bits;
+      }
+
+      if (q!=0)
+      {
+         int K = get_pulses(q);
+
+         /* Finally do the actual quantization */
+         if (encode)
+         {
+            cm = alg_quant(X, N, K, spread, B, ec, gain, ctx->resynth, ctx->arch);
+         } else {
+            cm = alg_unquant(X, N, K, spread, B, ec, gain);
+         }
+      } else {
+         /* If there's no pulse, fill the band anyway */
+         int j;
+         if (ctx->resynth)
+         {
+            unsigned cm_mask;
+            /* B can be as large as 16, so this shift might overflow an int on a
+               16-bit platform; use a long to get defined behavior.*/
+            cm_mask = (unsigned)(1UL<<B)-1;
+            fill &= cm_mask;
+            if (!fill)
+            {
+               OPUS_CLEAR(X, N);
+            } else {
+               if (lowband == NULL)
+               {
+                  /* Noise */
+                  for (j=0;j<N;j++)
+                  {
+                     ctx->seed = celt_lcg_rand(ctx->seed);
+                     X[j] = (celt_norm)((opus_int32)ctx->seed>>20);
+                  }
+                  cm = cm_mask;
+               } else {
+                  /* Folded spectrum */
+                  for (j=0;j<N;j++)
+                  {
+                     opus_val16 tmp;
+                     ctx->seed = celt_lcg_rand(ctx->seed);
+                     /* About 48 dB below the "normal" folding level */
+                     tmp = QCONST16(1.0f/256, 10);
+                     tmp = (ctx->seed)&0x8000 ? tmp : -tmp;
+                     X[j] = lowband[j]+tmp;
+                  }
+                  cm = fill;
+               }
+               renormalise_vector(X, N, gain, ctx->arch);
+            }
+         }
+      }
+   }
+
+   return cm;
+}
+
+
+/* This function is responsible for encoding and decoding a band for the mono case. */
+static unsigned quant_band(struct band_ctx *ctx, celt_norm *X,
+      int N, int b, int B, celt_norm *lowband,
+      int LM, celt_norm *lowband_out,
+      opus_val16 gain, celt_norm *lowband_scratch, int fill)
+{
+   int N0=N;
+   int N_B=N;
+   int N_B0;
+   int B0=B;
+   int time_divide=0;
+   int recombine=0;
+   int longBlocks;
+   unsigned cm=0;
+   int k;
+   int encode;
+   int tf_change;
+
+   encode = ctx->encode;
+   tf_change = ctx->tf_change;
+
+   longBlocks = B0==1;
+
+   N_B = celt_udiv(N_B, B);
+
+   /* Special case for one sample */
+   if (N==1)
+   {
+      return quant_band_n1(ctx, X, NULL, b, lowband_out);
+   }
+
+   if (tf_change>0)
+      recombine = tf_change;
+   /* Band recombining to increase frequency resolution */
+
+   if (lowband_scratch && lowband && (recombine || ((N_B&1) == 0 && tf_change<0) || B0>1))
+   {
+      OPUS_COPY(lowband_scratch, lowband, N);
+      lowband = lowband_scratch;
+   }
+
+   for (k=0;k<recombine;k++)
+   {
+      static const unsigned char bit_interleave_table[16]={
+            0,1,1,1,2,3,3,3,2,3,3,3,2,3,3,3
+      };
+      if (encode)
+         haar1(X, N>>k, 1<<k);
+      if (lowband)
+         haar1(lowband, N>>k, 1<<k);
+      fill = bit_interleave_table[fill&0xF]|bit_interleave_table[fill>>4]<<2;
+   }
+   B>>=recombine;
+   N_B<<=recombine;
+
+   /* Increasing the time resolution */
+   while ((N_B&1) == 0 && tf_change<0)
+   {
+      if (encode)
+         haar1(X, N_B, B);
+      if (lowband)
+         haar1(lowband, N_B, B);
+      fill |= fill<<B;
+      B <<= 1;
+      N_B >>= 1;
+      time_divide++;
+      tf_change++;
+   }
+   B0=B;
+   N_B0 = N_B;
+
+   /* Reorganize the samples in time order instead of frequency order */
+   if (B0>1)
+   {
+      if (encode)
+         deinterleave_hadamard(X, N_B>>recombine, B0<<recombine, longBlocks);
+      if (lowband)
+         deinterleave_hadamard(lowband, N_B>>recombine, B0<<recombine, longBlocks);
+   }
+
+   cm = quant_partition(ctx, X, N, b, B, lowband, LM, gain, fill);
+
+   /* This code is used by the decoder and by the resynthesis-enabled encoder */
+   if (ctx->resynth)
+   {
+      /* Undo the sample reorganization going from time order to frequency order */
+      if (B0>1)
+         interleave_hadamard(X, N_B>>recombine, B0<<recombine, longBlocks);
+
+      /* Undo time-freq changes that we did earlier */
+      N_B = N_B0;
+      B = B0;
+      for (k=0;k<time_divide;k++)
+      {
+         B >>= 1;
+         N_B <<= 1;
+         cm |= cm>>B;
+         haar1(X, N_B, B);
+      }
+
+      for (k=0;k<recombine;k++)
+      {
+         static const unsigned char bit_deinterleave_table[16]={
+               0x00,0x03,0x0C,0x0F,0x30,0x33,0x3C,0x3F,
+               0xC0,0xC3,0xCC,0xCF,0xF0,0xF3,0xFC,0xFF
+         };
+         cm = bit_deinterleave_table[cm];
+         haar1(X, N0>>k, 1<<k);
+      }
+      B<<=recombine;
+
+      /* Scale output for later folding */
+      if (lowband_out)
+      {
+         int j;
+         opus_val16 n;
+         n = celt_sqrt(SHL32(EXTEND32(N0),22));
+         for (j=0;j<N0;j++)
+            lowband_out[j] = MULT16_16_Q15(n,X[j]);
+      }
+      cm &= (1<<B)-1;
+   }
+   return cm;
+}
+
+
+/* This function is responsible for encoding and decoding a band for the stereo case. */
+static unsigned quant_band_stereo(struct band_ctx *ctx, celt_norm *X, celt_norm *Y,
+      int N, int b, int B, celt_norm *lowband,
+      int LM, celt_norm *lowband_out,
+      celt_norm *lowband_scratch, int fill)
+{
+   int imid=0, iside=0;
+   int inv = 0;
+   opus_val16 mid=0, side=0;
+   unsigned cm=0;
+   int mbits, sbits, delta;
+   int itheta;
+   int qalloc;
+   struct split_ctx sctx;
+   int orig_fill;
+   int encode;
+   ec_ctx *ec;
+
+   encode = ctx->encode;
+   ec = ctx->ec;
+
+   /* Special case for one sample */
+   if (N==1)
+   {
+      return quant_band_n1(ctx, X, Y, b, lowband_out);
+   }
+
+   orig_fill = fill;
+
+   compute_theta(ctx, &sctx, X, Y, N, &b, B, B, LM, 1, &fill);
+   inv = sctx.inv;
+   imid = sctx.imid;
+   iside = sctx.iside;
+   delta = sctx.delta;
+   itheta = sctx.itheta;
+   qalloc = sctx.qalloc;
+#ifdef FIXED_POINT
+   mid = imid;
+   side = iside;
+#else
+   mid = (1.f/32768)*imid;
+   side = (1.f/32768)*iside;
+#endif
+
+   /* This is a special case for N=2 that only works for stereo and takes
+      advantage of the fact that mid and side are orthogonal to encode
+      the side with just one bit. */
+   if (N==2)
+   {
+      int c;
+      int sign=0;
+      celt_norm *x2, *y2;
+      mbits = b;
+      sbits = 0;
+      /* Only need one bit for the side. */
+      if (itheta != 0 && itheta != 16384)
+         sbits = 1<<BITRES;
+      mbits -= sbits;
+      c = itheta > 8192;
+      ctx->remaining_bits -= qalloc+sbits;
+
+      x2 = c ? Y : X;
+      y2 = c ? X : Y;
+      if (sbits)
+      {
+         if (encode)
+         {
+            /* Here we only need to encode a sign for the side. */
+            sign = x2[0]*y2[1] - x2[1]*y2[0] < 0;
+            ec_enc_bits(ec, sign, 1);
+         } else {
+            sign = ec_dec_bits(ec, 1);
+         }
+      }
+      sign = 1-2*sign;
+      /* We use orig_fill here because we want to fold the side, but if
+         itheta==16384, we'll have cleared the low bits of fill. */
+      cm = quant_band(ctx, x2, N, mbits, B, lowband, LM, lowband_out, Q15ONE,
+            lowband_scratch, orig_fill);
+      /* We don't split N=2 bands, so cm is either 1 or 0 (for a fold-collapse),
+         and there's no need to worry about mixing with the other channel. */
+      y2[0] = -sign*x2[1];
+      y2[1] = sign*x2[0];
+      if (ctx->resynth)
+      {
+         celt_norm tmp;
+         X[0] = MULT16_16_Q15(mid, X[0]);
+         X[1] = MULT16_16_Q15(mid, X[1]);
+         Y[0] = MULT16_16_Q15(side, Y[0]);
+         Y[1] = MULT16_16_Q15(side, Y[1]);
+         tmp = X[0];
+         X[0] = SUB16(tmp,Y[0]);
+         Y[0] = ADD16(tmp,Y[0]);
+         tmp = X[1];
+         X[1] = SUB16(tmp,Y[1]);
+         Y[1] = ADD16(tmp,Y[1]);
+      }
+   } else {
+      /* "Normal" split code */
+      opus_int32 rebalance;
+
+      mbits = IMAX(0, IMIN(b, (b-delta)/2));
+      sbits = b-mbits;
+      ctx->remaining_bits -= qalloc;
+
+      rebalance = ctx->remaining_bits;
+      if (mbits >= sbits)
+      {
+         /* In stereo mode, we do not apply a scaling to the mid because we need the normalized
+            mid for folding later. */
+         cm = quant_band(ctx, X, N, mbits, B, lowband, LM, lowband_out, Q15ONE,
+               lowband_scratch, fill);
+         rebalance = mbits - (rebalance-ctx->remaining_bits);
+         if (rebalance > 3<<BITRES && itheta!=0)
+            sbits += rebalance - (3<<BITRES);
+
+         /* For a stereo split, the high bits of fill are always zero, so no
+            folding will be done to the side. */
+         cm |= quant_band(ctx, Y, N, sbits, B, NULL, LM, NULL, side, NULL, fill>>B);
+      } else {
+         /* For a stereo split, the high bits of fill are always zero, so no
+            folding will be done to the side. */
+         cm = quant_band(ctx, Y, N, sbits, B, NULL, LM, NULL, side, NULL, fill>>B);
+         rebalance = sbits - (rebalance-ctx->remaining_bits);
+         if (rebalance > 3<<BITRES && itheta!=16384)
+            mbits += rebalance - (3<<BITRES);
+         /* In stereo mode, we do not apply a scaling to the mid because we need the normalized
+            mid for folding later. */
+         cm |= quant_band(ctx, X, N, mbits, B, lowband, LM, lowband_out, Q15ONE,
+               lowband_scratch, fill);
+      }
+   }
+
+
+   /* This code is used by the decoder and by the resynthesis-enabled encoder */
+   if (ctx->resynth)
+   {
+      if (N!=2)
+         stereo_merge(X, Y, mid, N, ctx->arch);
+      if (inv)
+      {
+         int j;
+         for (j=0;j<N;j++)
+            Y[j] = -Y[j];
+      }
+   }
+   return cm;
+}
+
+static void special_hybrid_folding(const CELTMode *m, celt_norm *norm, celt_norm *norm2, int start, int M, int dual_stereo)
+{
+   int n1, n2;
+   const opus_int16 * OPUS_RESTRICT eBands = m->eBands;
+   n1 = M*(eBands[start+1]-eBands[start]);
+   n2 = M*(eBands[start+2]-eBands[start+1]);
+   /* Duplicate enough of the first band folding data to be able to fold the second band.
+      Copies no data for CELT-only mode. */
+   OPUS_COPY(&norm[n1], &norm[2*n1 - n2], n2-n1);
+   if (dual_stereo)
+      OPUS_COPY(&norm2[n1], &norm2[2*n1 - n2], n2-n1);
+}
+
+void quant_all_bands(int encode, const CELTMode *m, int start, int end,
+      celt_norm *X_, celt_norm *Y_, unsigned char *collapse_masks,
+      const celt_ener *bandE, int *pulses, int shortBlocks, int spread,
+      int dual_stereo, int intensity, int *tf_res, opus_int32 total_bits,
+      opus_int32 balance, ec_ctx *ec, int LM, int codedBands,
+      opus_uint32 *seed, int complexity, int arch, int disable_inv)
+{
+   int i;
+   opus_int32 remaining_bits;
+   const opus_int16 * OPUS_RESTRICT eBands = m->eBands;
+   celt_norm * OPUS_RESTRICT norm, * OPUS_RESTRICT norm2;
+   VARDECL(celt_norm, _norm);
+   VARDECL(celt_norm, _lowband_scratch);
+   VARDECL(celt_norm, X_save);
+   VARDECL(celt_norm, Y_save);
+   VARDECL(celt_norm, X_save2);
+   VARDECL(celt_norm, Y_save2);
+   VARDECL(celt_norm, norm_save2);
+   int resynth_alloc;
+   celt_norm *lowband_scratch;
+   int B;
+   int M;
+   int lowband_offset;
+   int update_lowband = 1;
+   int C = Y_ != NULL ? 2 : 1;
+   int norm_offset;
+   int theta_rdo = encode && Y_!=NULL && !dual_stereo && complexity>=8;
+#ifdef RESYNTH
+   int resynth = 1;
+#else
+   int resynth = !encode || theta_rdo;
+#endif
+   struct band_ctx ctx;
+   SAVE_STACK;
+
+   M = 1<<LM;
+   B = shortBlocks ? M : 1;
+   norm_offset = M*eBands[start];
+   /* No need to allocate norm for the last band because we don't need an
+      output in that band. */
+   ALLOC(_norm, C*(M*eBands[m->nbEBands-1]-norm_offset), celt_norm);
+   norm = _norm;
+   norm2 = norm + M*eBands[m->nbEBands-1]-norm_offset;
+
+   /* For decoding, we can use the last band as scratch space because we don't need that
+      scratch space for the last band and we don't care about the data there until we're
+      decoding the last band. */
+   if (encode && resynth)
+      resynth_alloc = M*(eBands[m->nbEBands]-eBands[m->nbEBands-1]);
+   else
+      resynth_alloc = ALLOC_NONE;
+   ALLOC(_lowband_scratch, resynth_alloc, celt_norm);
+   if (encode && resynth)
+      lowband_scratch = _lowband_scratch;
+   else
+      lowband_scratch = X_+M*eBands[m->nbEBands-1];
+   ALLOC(X_save, resynth_alloc, celt_norm);
+   ALLOC(Y_save, resynth_alloc, celt_norm);
+   ALLOC(X_save2, resynth_alloc, celt_norm);
+   ALLOC(Y_save2, resynth_alloc, celt_norm);
+   ALLOC(norm_save2, resynth_alloc, celt_norm);
+
+   lowband_offset = 0;
+   ctx.bandE = bandE;
+   ctx.ec = ec;
+   ctx.encode = encode;
+   ctx.intensity = intensity;
+   ctx.m = m;
+   ctx.seed = *seed;
+   ctx.spread = spread;
+   ctx.arch = arch;
+   ctx.disable_inv = disable_inv;
+   ctx.resynth = resynth;
+   ctx.theta_round = 0;
+   /* Avoid injecting noise in the first band on transients. */
+   ctx.avoid_split_noise = B > 1;
+   for (i=start;i<end;i++)
+   {
+      opus_int32 tell;
+      int b;
+      int N;
+      opus_int32 curr_balance;
+      int effective_lowband=-1;
+      celt_norm * OPUS_RESTRICT X, * OPUS_RESTRICT Y;
+      int tf_change=0;
+      unsigned x_cm;
+      unsigned y_cm;
+      int last;
+
+      ctx.i = i;
+      last = (i==end-1);
+
+      X = X_+M*eBands[i];
+      if (Y_!=NULL)
+         Y = Y_+M*eBands[i];
+      else
+         Y = NULL;
+      N = M*eBands[i+1]-M*eBands[i];
+      celt_assert(N > 0);
+      tell = ec_tell_frac(ec);
+
+      /* Compute how many bits we want to allocate to this band */
+      if (i != start)
+         balance -= tell;
+      remaining_bits = total_bits-tell-1;
+      ctx.remaining_bits = remaining_bits;
+      if (i <= codedBands-1)
+      {
+         curr_balance = celt_sudiv(balance, IMIN(3, codedBands-i));
+         b = IMAX(0, IMIN(16383, IMIN(remaining_bits+1,pulses[i]+curr_balance)));
+      } else {
+         b = 0;
+      }
+
+#ifndef DISABLE_UPDATE_DRAFT
+      if (resynth && (M*eBands[i]-N >= M*eBands[start] || i==start+1) && (update_lowband || lowband_offset==0))
+            lowband_offset = i;
+      if (i == start+1)
+         special_hybrid_folding(m, norm, norm2, start, M, dual_stereo);
+#else
+      if (resynth && M*eBands[i]-N >= M*eBands[start] && (update_lowband || lowband_offset==0))
+            lowband_offset = i;
+#endif
+
+      tf_change = tf_res[i];
+      ctx.tf_change = tf_change;
+      if (i>=m->effEBands)
+      {
+         X=norm;
+         if (Y_!=NULL)
+            Y = norm;
+         lowband_scratch = NULL;
+      }
+      if (last && !theta_rdo)
+         lowband_scratch = NULL;
+
+      /* Get a conservative estimate of the collapse_mask's for the bands we're
+         going to be folding from. */
+      if (lowband_offset != 0 && (spread!=SPREAD_AGGRESSIVE || B>1 || tf_change<0))
+      {
+         int fold_start;
+         int fold_end;
+         int fold_i;
+         /* This ensures we never repeat spectral content within one band */
+         effective_lowband = IMAX(0, M*eBands[lowband_offset]-norm_offset-N);
+         fold_start = lowband_offset;
+         while(M*eBands[--fold_start] > effective_lowband+norm_offset);
+         fold_end = lowband_offset-1;
+#ifndef DISABLE_UPDATE_DRAFT
+         while(++fold_end < i && M*eBands[fold_end] < effective_lowband+norm_offset+N);
+#else
+         while(M*eBands[++fold_end] < effective_lowband+norm_offset+N);
+#endif
+         x_cm = y_cm = 0;
+         fold_i = fold_start; do {
+           x_cm |= collapse_masks[fold_i*C+0];
+           y_cm |= collapse_masks[fold_i*C+C-1];
+         } while (++fold_i<fold_end);
+      }
+      /* Otherwise, we'll be using the LCG to fold, so all blocks will (almost
+         always) be non-zero. */
+      else
+         x_cm = y_cm = (1<<B)-1;
+
+      if (dual_stereo && i==intensity)
+      {
+         int j;
+
+         /* Switch off dual stereo to do intensity. */
+         dual_stereo = 0;
+         if (resynth)
+            for (j=0;j<M*eBands[i]-norm_offset;j++)
+               norm[j] = HALF32(norm[j]+norm2[j]);
+      }
+      if (dual_stereo)
+      {
+         x_cm = quant_band(&ctx, X, N, b/2, B,
+               effective_lowband != -1 ? norm+effective_lowband : NULL, LM,
+               last?NULL:norm+M*eBands[i]-norm_offset, Q15ONE, lowband_scratch, x_cm);
+         y_cm = quant_band(&ctx, Y, N, b/2, B,
+               effective_lowband != -1 ? norm2+effective_lowband : NULL, LM,
+               last?NULL:norm2+M*eBands[i]-norm_offset, Q15ONE, lowband_scratch, y_cm);
+      } else {
+         if (Y!=NULL)
+         {
+            if (theta_rdo && i < intensity)
+            {
+               ec_ctx ec_save, ec_save2;
+               struct band_ctx ctx_save, ctx_save2;
+               opus_val32 dist0, dist1;
+               unsigned cm, cm2;
+               int nstart_bytes, nend_bytes, save_bytes;
+               unsigned char *bytes_buf;
+               unsigned char bytes_save[1275];
+               opus_val16 w[2];
+               compute_channel_weights(bandE[i], bandE[i+m->nbEBands], w);
+               /* Make a copy. */
+               cm = x_cm|y_cm;
+               ec_save = *ec;
+               ctx_save = ctx;
+               OPUS_COPY(X_save, X, N);
+               OPUS_COPY(Y_save, Y, N);
+               /* Encode and round down. */
+               ctx.theta_round = -1;
+               x_cm = quant_band_stereo(&ctx, X, Y, N, b, B,
+                     effective_lowband != -1 ? norm+effective_lowband : NULL, LM,
+                     last?NULL:norm+M*eBands[i]-norm_offset, lowband_scratch, cm);
+               dist0 = MULT16_32_Q15(w[0], celt_inner_prod(X_save, X, N, arch)) + MULT16_32_Q15(w[1], celt_inner_prod(Y_save, Y, N, arch));
+
+               /* Save first result. */
+               cm2 = x_cm;
+               ec_save2 = *ec;
+               ctx_save2 = ctx;
+               OPUS_COPY(X_save2, X, N);
+               OPUS_COPY(Y_save2, Y, N);
+               if (!last)
+                  OPUS_COPY(norm_save2, norm+M*eBands[i]-norm_offset, N);
+               nstart_bytes = ec_save.offs;
+               nend_bytes = ec_save.storage;
+               bytes_buf = ec_save.buf+nstart_bytes;
+               save_bytes = nend_bytes-nstart_bytes;
+               OPUS_COPY(bytes_save, bytes_buf, save_bytes);
+
+               /* Restore */
+               *ec = ec_save;
+               ctx = ctx_save;
+               OPUS_COPY(X, X_save, N);
+               OPUS_COPY(Y, Y_save, N);
+#ifndef DISABLE_UPDATE_DRAFT
+               if (i == start+1)
+                  special_hybrid_folding(m, norm, norm2, start, M, dual_stereo);
+#endif
+               /* Encode and round up. */
+               ctx.theta_round = 1;
+               x_cm = quant_band_stereo(&ctx, X, Y, N, b, B,
+                     effective_lowband != -1 ? norm+effective_lowband : NULL, LM,
+                     last?NULL:norm+M*eBands[i]-norm_offset, lowband_scratch, cm);
+               dist1 = MULT16_32_Q15(w[0], celt_inner_prod(X_save, X, N, arch)) + MULT16_32_Q15(w[1], celt_inner_prod(Y_save, Y, N, arch));
+               if (dist0 >= dist1) {
+                  x_cm = cm2;
+                  *ec = ec_save2;
+                  ctx = ctx_save2;
+                  OPUS_COPY(X, X_save2, N);
+                  OPUS_COPY(Y, Y_save2, N);
+                  if (!last)
+                     OPUS_COPY(norm+M*eBands[i]-norm_offset, norm_save2, N);
+                  OPUS_COPY(bytes_buf, bytes_save, save_bytes);
+               }
+            } else {
+               ctx.theta_round = 0;
+               x_cm = quant_band_stereo(&ctx, X, Y, N, b, B,
+                     effective_lowband != -1 ? norm+effective_lowband : NULL, LM,
+                     last?NULL:norm+M*eBands[i]-norm_offset, lowband_scratch, x_cm|y_cm);
+            }
+         } else {
+            x_cm = quant_band(&ctx, X, N, b, B,
+                  effective_lowband != -1 ? norm+effective_lowband : NULL, LM,
+                  last?NULL:norm+M*eBands[i]-norm_offset, Q15ONE, lowband_scratch, x_cm|y_cm);
+         }
+         y_cm = x_cm;
+      }
+      collapse_masks[i*C+0] = (unsigned char)x_cm;
+      collapse_masks[i*C+C-1] = (unsigned char)y_cm;
+      balance += pulses[i] + tell;
+
+      /* Update the folding position only as long as we have 1 bit/sample depth. */
+      update_lowband = b>(N<<BITRES);
+      /* We only need to avoid noise on a split for the first band. After that, we
+         have folding. */
+      ctx.avoid_split_noise = 0;
+   }
+   *seed = ctx.seed;
+
+   RESTORE_STACK;
+}
+