static unsigned int celt_decode_band(CeltContext *s, OpusRangeCoder *rc, const int band, float *X, float *Y, int N, int b, unsigned int blocks, float *lowband, int duration, float *lowband_out, int level, float gain, float *lowband_scratch, int fill) { const uint8_t *cache; int dualstereo, split; int imid = 0, iside = 0; unsigned int N0 = N; int N_B; int N_B0; int B0 = blocks; int time_divide = 0; int recombine = 0; int inv = 0; float mid = 0, side = 0; int longblocks = (B0 == 1); unsigned int cm = 0; N_B0 = N_B = N / blocks; split = dualstereo = (Y != NULL); if (N == 1) { /* special case for one sample */ int i; float *x = X; for (i = 0; i <= dualstereo; i++) { int sign = 0; if (s->remaining2 >= 1<<3) { sign = opus_getrawbits(rc, 1); s->remaining2 -= 1 << 3; b -= 1 << 3; } x[0] = sign ? -1.0f : 1.0f; x = Y; } if (lowband_out) lowband_out[0] = X[0]; return 1; } if (!dualstereo && level == 0) { int tf_change = s->tf_change[band]; int k; if (tf_change > 0) recombine = tf_change; /* Band recombining to increase frequency resolution */ if (lowband && (recombine || ((N_B & 1) == 0 && tf_change < 0) || B0 > 1)) { int j; for (j = 0; j < N; j++) lowband_scratch[j] = lowband[j]; lowband = lowband_scratch; } for (k = 0; k < recombine; k++) { if (lowband) celt_haar1(lowband, N >> k, 1 << k); fill = celt_bit_interleave[fill & 0xF] | celt_bit_interleave[fill >> 4] << 2; } blocks >>= recombine; N_B <<= recombine; /* Increasing the time resolution */ while ((N_B & 1) == 0 && tf_change < 0) { if (lowband) celt_haar1(lowband, N_B, blocks); fill |= fill << blocks; blocks <<= 1; N_B >>= 1; time_divide++; tf_change++; } B0 = blocks; N_B0 = N_B; /* Reorganize the samples in time order instead of frequency order */ if (B0 > 1 && lowband) celt_deinterleave_hadamard(s->scratch, lowband, N_B >> recombine, B0 << recombine, longblocks); } /* If we need 1.5 more bit than we can produce, split the band in two. */ cache = celt_cache_bits + celt_cache_index[(duration + 1) * CELT_MAX_BANDS + band]; if (!dualstereo && duration >= 0 && b > cache[cache[0]] + 12 && N > 2) { N >>= 1; Y = X + N; split = 1; duration -= 1; if (blocks == 1) fill = (fill & 1) | (fill << 1); blocks = (blocks + 1) >> 1; } if (split) { int qn; int itheta = 0; int mbits, sbits, delta; int qalloc; int pulse_cap; int offset; int orig_fill; int tell; /* Decide on the resolution to give to the split parameter theta */ pulse_cap = celt_log_freq_range[band] + duration * 8; offset = (pulse_cap >> 1) - (dualstereo && N == 2 ? CELT_QTHETA_OFFSET_TWOPHASE : CELT_QTHETA_OFFSET); qn = (dualstereo && band >= s->intensitystereo) ? 1 : celt_compute_qn(N, b, offset, pulse_cap, dualstereo); tell = opus_rc_tell_frac(rc); if (qn != 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 (dualstereo && N > 2) itheta = opus_rc_stepmodel(rc, qn/2); else if (dualstereo || B0 > 1) itheta = opus_rc_unimodel(rc, qn+1); else itheta = opus_rc_trimodel(rc, qn); itheta = itheta * 16384 / qn; /* NOTE: Renormalising X and Y *may* help fixed-point a bit at very high rate. Let's do that at higher complexity */ } else if (dualstereo) { inv = (b > 2 << 3 && s->remaining2 > 2 << 3) ? opus_rc_p2model(rc, 2) : 0; itheta = 0; } qalloc = opus_rc_tell_frac(rc) - tell; b -= qalloc; orig_fill = fill; if (itheta == 0) { imid = 32767; iside = 0; fill &= (1 << blocks) - 1; delta = -16384; } else if (itheta == 16384) { imid = 0; iside = 32767; fill &= ((1 << blocks) - 1) << blocks; delta = 16384; } else { imid = celt_cos(itheta); iside = celt_cos(16384-itheta); /* This is the mid vs side allocation that minimizes squared error in that band. */ delta = ROUND_MUL16((N - 1) << 7, celt_log2tan(iside, imid)); } mid = imid / 32768.0f; side = iside / 32768.0f; /* 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 && dualstereo) { int c; int sign = 0; float tmp; float *x2, *y2; mbits = b; /* Only need one bit for the side */ sbits = (itheta != 0 && itheta != 16384) ? 1 << 3 : 0; mbits -= sbits; c = (itheta > 8192); s->remaining2 -= qalloc+sbits; x2 = c ? Y : X; y2 = c ? X : Y; if (sbits) sign = opus_getrawbits(rc, 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 = celt_decode_band(s, rc, band, x2, NULL, N, mbits, blocks, lowband, duration, lowband_out, level, gain, 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]; X[0] *= mid; X[1] *= mid; Y[0] *= side; Y[1] *= side; tmp = X[0]; X[0] = tmp - Y[0]; Y[0] = tmp + Y[0]; tmp = X[1]; X[1] = tmp - Y[1]; Y[1] = tmp + Y[1]; } else { /* "Normal" split code */ float *next_lowband2 = NULL; float *next_lowband_out1 = NULL; int next_level = 0; int rebalance; /* Give more bits to low-energy MDCTs than they would * otherwise deserve */ if (B0 > 1 && !dualstereo && (itheta & 0x3fff)) { if (itheta > 8192) /* Rough approximation for pre-echo masking */ delta -= delta >> (4 - duration); else /* Corresponds to a forward-masking slope of * 1.5 dB per 10 ms */ delta = FFMIN(0, delta + (N << 3 >> (5 - duration))); } mbits = av_clip((b - delta) / 2, 0, b); sbits = b - mbits; s->remaining2 -= qalloc; if (lowband && !dualstereo) next_lowband2 = lowband + N; /* >32-bit split case */ /* Only stereo needs to pass on lowband_out. * Otherwise, it's handled at the end */ if (dualstereo) next_lowband_out1 = lowband_out; else next_level = level + 1; rebalance = s->remaining2; 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 = celt_decode_band(s, rc, band, X, NULL, N, mbits, blocks, lowband, duration, next_lowband_out1, next_level, dualstereo ? 1.0f : (gain * mid), lowband_scratch, fill); rebalance = mbits - (rebalance - s->remaining2); if (rebalance > 3 << 3 && itheta != 0) sbits += rebalance - (3 << 3); /* For a stereo split, the high bits of fill are always zero, * so no folding will be done to the side. */ cm |= celt_decode_band(s, rc, band, Y, NULL, N, sbits, blocks, next_lowband2, duration, NULL, next_level, gain * side, NULL, fill >> blocks) << ((B0 >> 1) & (dualstereo - 1)); } else { /* For a stereo split, the high bits of fill are always zero, * so no folding will be done to the side. */ cm = celt_decode_band(s, rc, band, Y, NULL, N, sbits, blocks, next_lowband2, duration, NULL, next_level, gain * side, NULL, fill >> blocks) << ((B0 >> 1) & (dualstereo - 1)); rebalance = sbits - (rebalance - s->remaining2); if (rebalance > 3 << 3 && itheta != 16384) mbits += rebalance - (3 << 3); /* In stereo mode, we do not apply a scaling to the mid because * we need the normalized mid for folding later */ cm |= celt_decode_band(s, rc, band, X, NULL, N, mbits, blocks, lowband, duration, next_lowband_out1, next_level, dualstereo ? 1.0f : (gain * mid), lowband_scratch, fill); } } } else { /* This is the basic no-split case */ unsigned int q = celt_bits2pulses(cache, b); unsigned int curr_bits = celt_pulses2bits(cache, q); s->remaining2 -= curr_bits; /* Ensures we can never bust the budget */ while (s->remaining2 < 0 && q > 0) { s->remaining2 += curr_bits; curr_bits = celt_pulses2bits(cache, --q); s->remaining2 -= curr_bits; } if (q != 0) { /* Finally do the actual quantization */ cm = celt_alg_unquant(rc, X, N, (q < 8) ? q : (8 + (q & 7)) << ((q >> 3) - 1), s->spread, blocks, gain); } else { /* If there's no pulse, fill the band anyway */ int j; unsigned int cm_mask = (1 << blocks) - 1; fill &= cm_mask; if (!fill) { for (j = 0; j < N; j++) X[j] = 0.0f; } else { if (lowband == NULL) { /* Noise */ for (j = 0; j < N; j++) X[j] = (((int32_t)celt_rng(s)) >> 20); cm = cm_mask; } else { /* Folded spectrum */ for (j = 0; j < N; j++) { /* About 48 dB below the "normal" folding level */ X[j] = lowband[j] + (((celt_rng(s)) & 0x8000) ? 1.0f / 256 : -1.0f / 256); } cm = fill; } celt_renormalize_vector(X, N, gain); } } } /* This code is used by the decoder and by the resynthesis-enabled encoder */ if (dualstereo) { int j; if (N != 2) celt_stereo_merge(X, Y, mid, N); if (inv) { for (j = 0; j < N; j++) Y[j] *= -1; } } else if (level == 0) { int k; /* Undo the sample reorganization going from time order to frequency order */ if (B0 > 1) celt_interleave_hadamard(s->scratch, X, N_B>>recombine, B0<<recombine, longblocks); /* Undo time-freq changes that we did earlier */ N_B = N_B0; blocks = B0; for (k = 0; k < time_divide; k++) { blocks >>= 1; N_B <<= 1; cm |= cm >> blocks; celt_haar1(X, N_B, blocks); } for (k = 0; k < recombine; k++) { cm = celt_bit_deinterleave[cm]; celt_haar1(X, N0>>k, 1<<k); } blocks <<= recombine; /* Scale output for later folding */ if (lowband_out) { int j; float n = sqrtf(N0); for (j = 0; j < N0; j++) lowband_out[j] = n * X[j]; } cm &= (1 << blocks) - 1; } return cm; }