1 files changed, 247 insertions, 104 deletions

diff --git a/lib/rbcodec/codecs/libopus/celt/bands.c b/lib/rbcodec/codecs/libopus/celt/bands.c
index caa70163b4..2702963c37 100644
--- a/lib/rbcodec/codecs/libopus/celt/bands.c
+++ b/lib/rbcodec/codecs/libopus/celt/bands.c
@@ -65,19 +65,19 @@ opus_uint32 celt_lcg_rand(opus_uint32 seed)
 
 /* 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 */
-static opus_int16 bitexact_cos(opus_int16 x)
+opus_int16 bitexact_cos(opus_int16 x)
 {
    opus_int32 tmp;
    opus_int16 x2;
    tmp = (4096+((opus_int32)(x)*(x)))>>13;
-   celt_assert(tmp<=32767);
+   celt_sig_assert(tmp<=32767);
    x2 = tmp;
    x2 = (32767-x2) + FRAC_MUL16(x2, (-7651 + FRAC_MUL16(x2, (8277 + FRAC_MUL16(-626, x2)))));
-   celt_assert(x2<=32766);
+   celt_sig_assert(x2<=32766);
    return 1+x2;
 }
 
-static int bitexact_log2tan(int isin,int icos)
+int bitexact_log2tan(int isin,int icos)
 {
    int lc;
    int ls;
@@ -90,13 +90,13 @@ static int bitexact_log2tan(int isin,int icos)
          -FRAC_MUL16(icos, FRAC_MUL16(icos, -2597) + 7932);
 }
 
-#if 0
 #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)
+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++)
@@ -156,7 +156,7 @@ 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 LM)
+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;
@@ -165,7 +165,7 @@ void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *band
       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);
+         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]);*/
       }
@@ -191,7 +191,6 @@ void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, cel
 }
 
 #endif /* FIXED_POINT */
-#endif
 
 /* 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,
@@ -226,9 +225,9 @@ void denormalise_bands(const CELTMode *m, const celt_norm * OPUS_RESTRICT X,
 #endif
       j=M*eBands[i];
       band_end = M*eBands[i+1];
-      lg = ADD16(bandLogE[i], SHL16((opus_val16)eMeans[i],6));
+      lg = SATURATE16(ADD32(bandLogE[i], SHL32((opus_val32)eMeans[i],6)));
 #ifndef FIXED_POINT
-      g = celt_exp2(lg);
+      g = celt_exp2(MIN32(32.f, lg));
 #else
       /* Handle the integer part of the log energy */
       shift = 16-(lg>>DB_SHIFT);
@@ -243,12 +242,12 @@ void denormalise_bands(const CELTMode *m, const celt_norm * OPUS_RESTRICT X,
       /* Handle extreme gains with negative shift. */
       if (shift<0)
       {
-         /* For shift < -2 we'd be likely to overflow, so we're capping
-               the gain here. This shouldn't happen unless the bitstream is
-               already corrupted. */
-         if (shift < -2)
+         /* 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 = 32767;
+            g = 16384;
             shift = -2;
          }
          do {
@@ -268,7 +267,7 @@ void denormalise_bands(const CELTMode *m, const celt_norm * OPUS_RESTRICT X,
 /* 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)
+      const opus_val16 *prev2logE, const int *pulses, opus_uint32 seed, int arch)
 {
    int c, i, j, k;
    for (i=start;i<end;i++)
@@ -283,7 +282,7 @@ void anti_collapse(const CELTMode *m, celt_norm *X_, unsigned char *collapse_mas
 
       N0 = m->eBands[i+1]-m->eBands[i];
       /* depth in 1/8 bits */
-      celt_assert(pulses[i]>=0);
+      celt_sig_assert(pulses[i]>=0);
       depth = celt_udiv(1+pulses[i], (m->eBands[i+1]-m->eBands[i]))>>LM;
 
 #ifdef FIXED_POINT
@@ -357,11 +356,35 @@ void anti_collapse(const CELTMode *m, celt_norm *X_, unsigned char *collapse_mas
          }
          /* We just added some energy, so we need to renormalise */
          if (renormalize)
-            renormalise_vector(X, N0<<LM, Q15ONE);
+            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;
+#ifdef 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);
+#ifdef 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;
@@ -400,7 +423,7 @@ static void stereo_split(celt_norm * OPUS_RESTRICT X, celt_norm * OPUS_RESTRICT
    }
 }
 
-static void stereo_merge(celt_norm * OPUS_RESTRICT X, celt_norm * OPUS_RESTRICT Y, opus_val16 mid, int N)
+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;
@@ -412,11 +435,11 @@ static void stereo_merge(celt_norm * OPUS_RESTRICT X, celt_norm * OPUS_RESTRICT
    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);
+   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 = SHR32(mid, 1);
+   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))
@@ -452,11 +475,10 @@ static void stereo_merge(celt_norm * OPUS_RESTRICT X, celt_norm * OPUS_RESTRICT
    }
 }
 
-#if 0
 /* 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)
+      int end, int C, int M, const int *spread_weight)
 {
    int i, c, N0;
    int sum = 0, nbBands=0;
@@ -497,8 +519,8 @@ int spreading_decision(const CELTMode *m, const celt_norm *X, int *average,
          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*256;
-         nbBands++;
+         sum += tmp*spread_weight[i];
+         nbBands+=spread_weight[i];
       }
    } while (++c<C);
 
@@ -522,7 +544,7 @@ int spreading_decision(const CELTMode *m, const celt_norm *X, int *average,
    /*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(sum, nbBands);
+   sum = celt_udiv((opus_int32)sum<<8, nbBands);
    /* Recursive averaging */
    sum = (sum+*average)>>1;
    *average = sum;
@@ -546,7 +568,6 @@ int spreading_decision(const CELTMode *m, const celt_norm *X, int *average,
 #endif
    return decision;
 }
-#endif
 
 /* Indexing table for converting from natural Hadamard to ordery Hadamard
    This is essentially a bit-reversed Gray, on top of which we've added
@@ -651,6 +672,7 @@ static int compute_qn(int N, int b, int offset, int pulse_cap, int stereo)
 
 struct band_ctx {
    int encode;
+   int resynth;
    const CELTMode *m;
    int i;
    int intensity;
@@ -660,6 +682,10 @@ struct band_ctx {
    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 {
@@ -711,14 +737,41 @@ static void compute_theta(struct band_ctx *ctx, struct split_ctx *sctx,
          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);
+      itheta = stereo_itheta(X, Y, stereo, N, ctx->arch);
    }
    tell = ec_tell_frac(ec);
    if (qn!=1)
    {
       if (encode)
-         itheta = (itheta*qn+8192)>>14;
-
+      {
+         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)
@@ -796,7 +849,7 @@ static void compute_theta(struct band_ctx *ctx, struct split_ctx *sctx,
    } else if (stereo) {
       if (encode)
       {
-         inv = itheta > 8192;
+         inv = itheta > 8192 && !ctx->disable_inv;
          if (inv)
          {
             int j;
@@ -813,6 +866,9 @@ static void compute_theta(struct band_ctx *ctx, struct split_ctx *sctx,
             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;
@@ -848,11 +904,6 @@ static void compute_theta(struct band_ctx *ctx, struct split_ctx *sctx,
 static unsigned quant_band_n1(struct band_ctx *ctx, celt_norm *X, celt_norm *Y, int b,
       celt_norm *lowband_out)
 {
-#ifdef RESYNTH
-   int resynth = 1;
-#else
-   int resynth = !ctx->encode;
-#endif
    int c;
    int stereo;
    celt_norm *x = X;
@@ -877,7 +928,7 @@ static unsigned quant_band_n1(struct band_ctx *ctx, celt_norm *X, celt_norm *Y,
          ctx->remaining_bits -= 1<<BITRES;
          b-=1<<BITRES;
       }
-      if (resynth)
+      if (ctx->resynth)
          x[0] = sign ? -NORM_SCALING : NORM_SCALING;
       x = Y;
    } while (++c<1+stereo);
@@ -902,11 +953,6 @@ static unsigned quant_partition(struct band_ctx *ctx, celt_norm *X,
    int B0=B;
    opus_val16 mid=0, side=0;
    unsigned cm=0;
-#ifdef RESYNTH
-   int resynth = 1;
-#else
-   int resynth = !ctx->encode;
-#endif
    celt_norm *Y=NULL;
    int encode;
    const CELTMode *m;
@@ -938,8 +984,7 @@ static unsigned quant_partition(struct band_ctx *ctx, celt_norm *X,
          fill = (fill&1)|(fill<<1);
       B = (B+1)>>1;
 
-      compute_theta(ctx, &sctx, X, Y, N, &b, B, B0,
-            LM, 0, &fill);
+      compute_theta(ctx, &sctx, X, Y, N, &b, B, B0, LM, 0, &fill);
       imid = sctx.imid;
       iside = sctx.iside;
       delta = sctx.delta;
@@ -973,24 +1018,20 @@ static unsigned quant_partition(struct band_ctx *ctx, celt_norm *X,
       rebalance = ctx->remaining_bits;
       if (mbits >= sbits)
       {
-         cm = quant_partition(ctx, X, N, mbits, B,
-               lowband, LM,
+         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,
+         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,
+         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,
+         cm |= quant_partition(ctx, X, N, mbits, B, lowband, LM,
                MULT16_16_P15(gain,mid), fill);
       }
    } else {
@@ -1015,18 +1056,14 @@ static unsigned quant_partition(struct band_ctx *ctx, celt_norm *X,
          /* Finally do the actual quantization */
          if (encode)
          {
-            cm = alg_quant(X, N, K, spread, B, ec
-#ifdef RESYNTH
-                 , gain
-#endif
-                 );
+            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 (resynth)
+         if (ctx->resynth)
          {
             unsigned cm_mask;
             /* B can be as large as 16, so this shift might overflow an int on a
@@ -1059,7 +1096,7 @@ static unsigned quant_partition(struct band_ctx *ctx, celt_norm *X,
                   }
                   cm = fill;
                }
-               renormalise_vector(X, N, gain);
+               renormalise_vector(X, N, gain, ctx->arch);
             }
          }
       }
@@ -1083,11 +1120,6 @@ static unsigned quant_band(struct band_ctx *ctx, celt_norm *X,
    int recombine=0;
    int longBlocks;
    unsigned cm=0;
-#ifdef RESYNTH
-   int resynth = 1;
-#else
-   int resynth = !ctx->encode;
-#endif
    int k;
    int encode;
    int tf_change;
@@ -1154,11 +1186,10 @@ static unsigned quant_band(struct band_ctx *ctx, celt_norm *X,
          deinterleave_hadamard(lowband, N_B>>recombine, B0<<recombine, longBlocks);
    }
 
-   cm = quant_partition(ctx, X, N, b, B, lowband,
-         LM, gain, fill);
+   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 (resynth)
+   if (ctx->resynth)
    {
       /* Undo the sample reorganization going from time order to frequency order */
       if (B0>1)
@@ -1211,11 +1242,6 @@ static unsigned quant_band_stereo(struct band_ctx *ctx, celt_norm *X, celt_norm
    int inv = 0;
    opus_val16 mid=0, side=0;
    unsigned cm=0;
-#ifdef RESYNTH
-   int resynth = 1;
-#else
-   int resynth = !ctx->encode;
-#endif
    int mbits, sbits, delta;
    int itheta;
    int qalloc;
@@ -1235,8 +1261,7 @@ static unsigned quant_band_stereo(struct band_ctx *ctx, celt_norm *X, celt_norm
 
    orig_fill = fill;
 
-   compute_theta(ctx, &sctx, X, Y, N, &b, B, B,
-         LM, 1, &fill);
+   compute_theta(ctx, &sctx, X, Y, N, &b, B, B, LM, 1, &fill);
    inv = sctx.inv;
    imid = sctx.imid;
    iside = sctx.iside;
@@ -1284,13 +1309,13 @@ static unsigned quant_band_stereo(struct band_ctx *ctx, celt_norm *X, celt_norm
       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);
+      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 (resynth)
+      if (ctx->resynth)
       {
          celt_norm tmp;
          X[0] = MULT16_16_Q15(mid, X[0]);
@@ -1317,41 +1342,35 @@ static unsigned quant_band_stereo(struct band_ctx *ctx, celt_norm *X, celt_norm
       {
          /* 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);
+         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);
+         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);
+         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);
+         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 (resynth)
+   if (ctx->resynth)
    {
       if (N!=2)
-         stereo_merge(X, Y, mid, N);
+         stereo_merge(X, Y, mid, N, ctx->arch);
       if (inv)
       {
          int j;
@@ -1362,17 +1381,38 @@ static unsigned quant_band_stereo(struct band_ctx *ctx, celt_norm *X, celt_norm
    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)
+      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;
@@ -1380,10 +1420,11 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
    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;
+   int resynth = !encode || theta_rdo;
 #endif
    struct band_ctx ctx;
    SAVE_STACK;
@@ -1396,9 +1437,24 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
    ALLOC(_norm, C*(M*eBands[m->nbEBands-1]-norm_offset), celt_norm);
    norm = _norm;
    norm2 = norm + M*eBands[m->nbEBands-1]-norm_offset;
-   /* We can use the last band as scratch space because we don't need that
-      scratch space for the last band. */
-   lowband_scratch = X_+M*eBands[m->nbEBands-1];
+
+   /* 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;
@@ -1408,6 +1464,12 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
    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;
@@ -1430,6 +1492,7 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
       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 */
@@ -1445,8 +1508,15 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
          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;
@@ -1457,7 +1527,7 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
             Y = norm;
          lowband_scratch = NULL;
       }
-      if (i==end-1)
+      if (last && !theta_rdo)
          lowband_scratch = NULL;
 
       /* Get a conservative estimate of the collapse_mask's for the bands we're
@@ -1472,7 +1542,11 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
          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];
@@ -1505,13 +1579,79 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
       } else {
          if (Y!=NULL)
          {
-            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);
+            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);
+                  last?NULL:norm+M*eBands[i]-norm_offset, Q15ONE, lowband_scratch, x_cm|y_cm);
          }
          y_cm = x_cm;
       }
@@ -1521,6 +1661,9 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
 
       /* 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;