ac3enc: add channel coupling support

Channel coupling is an optional AC-3 feature that increases quality by
combining high frequency information from multiple channels into a
single channel. The per-channel high frequency information is sent with
less accuracy in both the frequency and time domains. This allows more
bits to be used for lower frequencies while preserving enough
information to reconstruct the high frequencies.

1 files changed, 729 insertions, 163 deletions

diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
index 95bdc58f16..5014fdb753 100644
--- a/libavcodec/ac3enc.c
+++ b/libavcodec/ac3enc.c
@@ -99,6 +99,8 @@ typedef struct AC3EncOptions {
     /* other encoding options */
     int allow_per_frame_metadata;
     int stereo_rematrixing;
+    int channel_coupling;
+    int cpl_start;
 } AC3EncOptions;
 
 /**
@@ -114,10 +116,22 @@ typedef struct AC3Block {
     int16_t  **band_psd;                        ///< psd per critical band
     int16_t  **mask;                            ///< masking curve
     uint16_t **qmant;                           ///< quantized mantissas
+    uint8_t  **cpl_coord_exp;                   ///< coupling coord exponents           (cplcoexp)
+    uint8_t  **cpl_coord_mant;                  ///< coupling coord mantissas           (cplcomant)
     uint8_t  coeff_shift[AC3_MAX_CHANNELS];     ///< fixed-point coefficient shift values
     uint8_t  new_rematrixing_strategy;          ///< send new rematrixing flags in this block
+    int      num_rematrixing_bands;             ///< number of rematrixing bands
     uint8_t  rematrixing_flags[4];              ///< rematrixing flags
     struct AC3Block *exp_ref_block[AC3_MAX_CHANNELS]; ///< reference blocks for EXP_REUSE
+    int      new_cpl_strategy;                  ///< send new coupling strategy
+    int      cpl_in_use;                        ///< coupling in use for this block     (cplinu)
+    uint8_t  channel_in_cpl[AC3_MAX_CHANNELS];  ///< channel in coupling                (chincpl)
+    int      num_cpl_channels;                  ///< number of channels in coupling
+    uint8_t  new_cpl_coords;                    ///< send new coupling coordinates      (cplcoe)
+    uint8_t  cpl_master_exp[AC3_MAX_CHANNELS];  ///< coupling coord master exponents    (mstrcplco)
+    int      new_snr_offsets;                   ///< send new SNR offsets
+    int      new_cpl_leak;                      ///< send new coupling leak info
+    int      end_freq[AC3_MAX_CHANNELS];        ///< end frequency bin                  (endmant)
 } AC3Block;
 
 /**
@@ -164,10 +178,16 @@ typedef struct AC3EncodeContext {
 
     int cutoff;                             ///< user-specified cutoff frequency, in Hz
     int bandwidth_code;                     ///< bandwidth code (0 to 60)               (chbwcod)
-    int nb_coefs[AC3_MAX_CHANNELS];
+    int start_freq[AC3_MAX_CHANNELS];       ///< start frequency bin                    (strtmant)
+    int cpl_end_freq;                       ///< coupling channel end frequency bin
+
+    int cpl_on;                             ///< coupling turned on for this frame
+    int cpl_enabled;                        ///< coupling enabled for all frames
+    int num_cpl_subbands;                   ///< number of coupling subbands            (ncplsubnd)
+    int num_cpl_bands;                      ///< number of coupling bands               (ncplbnd)
+    uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS];  ///< number of coeffs in each coupling band
 
     int rematrixing_enabled;                ///< stereo rematrixing enabled
-    int num_rematrixing_bands;              ///< number of rematrixing bands
 
     /* bitrate allocation control */
     int slow_gain_code;                     ///< slow gain code                         (sgaincod)
@@ -194,6 +214,8 @@ typedef struct AC3EncodeContext {
     int16_t *band_psd_buffer;
     int16_t *mask_buffer;
     uint16_t *qmant_buffer;
+    uint8_t *cpl_coord_exp_buffer;
+    uint8_t *cpl_coord_mant_buffer;
 
     uint8_t exp_strategy[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS]; ///< exponent strategies
 
@@ -267,6 +289,12 @@ static const AVOption options[] = {
     {"hdcd",     "HDCD",               0, FF_OPT_TYPE_CONST, {.dbl = 1 }, INT_MIN, INT_MAX, AC3ENC_PARAM, "ad_conv_type"},
 /* Other Encoding Options */
 {"stereo_rematrixing", "Stereo Rematrixing", OFFSET(stereo_rematrixing), FF_OPT_TYPE_INT, {.dbl = 1 }, 0, 1, AC3ENC_PARAM},
+#if CONFIG_AC3ENC_FLOAT
+{"channel_coupling",   "Channel Coupling",   OFFSET(channel_coupling),   FF_OPT_TYPE_INT, {.dbl = 1 }, 0, 1, AC3ENC_PARAM, "channel_coupling"},
+    {"auto", "Selected by the Encoder", 0, FF_OPT_TYPE_CONST, {.dbl = -1 }, INT_MIN, INT_MAX, AC3ENC_PARAM, "channel_coupling"},
+{"cpl_start_band", "Coupling Start Band", OFFSET(cpl_start), FF_OPT_TYPE_INT, {.dbl = -1 }, -1, 15, AC3ENC_PARAM, "cpl_start_band"},
+    {"auto", "Selected by the Encoder", 0, FF_OPT_TYPE_CONST, {.dbl = -1 }, INT_MIN, INT_MAX, AC3ENC_PARAM, "cpl_start_band"},
+#endif
 {NULL}
 };
 
@@ -296,9 +324,9 @@ static void scale_coefficients(AC3EncodeContext *s);
 
 /**
  * LUT for number of exponent groups.
- * exponent_group_tab[exponent strategy-1][number of coefficients]
+ * exponent_group_tab[coupling][exponent strategy-1][number of coefficients]
  */
-static uint8_t exponent_group_tab[3][256];
+static uint8_t exponent_group_tab[2][3][256];
 
 
 /**
@@ -358,6 +386,49 @@ static const uint8_t ac3_bandwidth_tab[5][3][19] = {
 
 
 /**
+ * LUT to select the coupling start band based on the bit rate, sample rate, and
+ * number of full-bandwidth channels. -1 = coupling off
+ * ac3_coupling_start_tab[channel_mode-2][sample rate code][bit rate code]
+ *
+ * TODO: more testing for optimal parameters.
+ *       multi-channel tests at 44.1kHz and 32kHz.
+ */
+static const int8_t ac3_coupling_start_tab[6][3][19] = {
+//      32  40  48  56  64  80  96 112 128 160 192 224 256 320 384 448 512 576 640
+
+    // 2/0
+    { {  0,  0,  0,  0,  0,  0,  0,  1,  1,  7,  8, 11, 12, -1, -1, -1, -1, -1, -1 },
+      {  0,  0,  0,  0,  0,  0,  1,  3,  5,  7, 10, 12, 13, -1, -1, -1, -1, -1, -1 },
+      {  0,  0,  0,  0,  1,  2,  2,  9, 13, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
+
+    // 3/0
+    { {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
+      {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
+      { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
+
+    // 2/1 - untested
+    { {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
+      {  0,  0,  0,  0,  0,  0,  0,  0,  2,  2,  6,  9, 11, 12, 13, -1, -1, -1, -1 },
+      { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
+
+    // 3/1
+    { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
+      {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
+      { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
+
+    // 2/2 - untested
+    { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
+      {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  3,  2, 10, 11, 11, 12, 12, 14, -1 },
+      { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
+
+    // 3/2
+    { {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1,  6,  8, 11, 12, 12, -1, -1 },
+      {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  1,  6,  8, 11, 12, 12, -1, -1 },
+      { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 } },
+};
+
+
+/**
  * Adjust the frame size to make the average bit rate match the target bit rate.
  * This is only needed for 11025, 22050, and 44100 sample rates.
  */
@@ -419,15 +490,297 @@ static void apply_mdct(AC3EncodeContext *s)
 
             apply_window(&s->dsp, s->windowed_samples, input_samples, s->mdct.window, AC3_WINDOW_SIZE);
 
-            block->coeff_shift[ch] = normalize_samples(s);
+            block->coeff_shift[ch+1] = normalize_samples(s);
 
-            s->mdct.fft.mdct_calcw(&s->mdct.fft, block->mdct_coef[ch],
+            s->mdct.fft.mdct_calcw(&s->mdct.fft, block->mdct_coef[ch+1],
                                    s->windowed_samples);
         }
     }
 }
 
 
+static void compute_coupling_strategy(AC3EncodeContext *s)
+{
+    int blk, ch;
+    int got_cpl_snr;
+
+    /* set coupling use flags for each block/channel */
+    /* TODO: turn coupling on/off and adjust start band based on bit usage */
+    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        AC3Block *block = &s->blocks[blk];
+        for (ch = 1; ch <= s->fbw_channels; ch++)
+            block->channel_in_cpl[ch] = s->cpl_on;
+    }
+
+    /* enable coupling for each block if at least 2 channels have coupling
+       enabled for that block */
+    got_cpl_snr = 0;
+    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        AC3Block *block = &s->blocks[blk];
+        block->num_cpl_channels = 0;
+        for (ch = 1; ch <= s->fbw_channels; ch++)
+            block->num_cpl_channels += block->channel_in_cpl[ch];
+        block->cpl_in_use = block->num_cpl_channels > 1;
+        if (!block->cpl_in_use) {
+            block->num_cpl_channels = 0;
+            for (ch = 1; ch <= s->fbw_channels; ch++)
+                block->channel_in_cpl[ch] = 0;
+        }
+
+        block->new_cpl_strategy = !blk;
+        if (blk) {
+            for (ch = 1; ch <= s->fbw_channels; ch++) {
+                if (block->channel_in_cpl[ch] != s->blocks[blk-1].channel_in_cpl[ch]) {
+                    block->new_cpl_strategy = 1;
+                    break;
+                }
+            }
+        }
+        block->new_cpl_leak = block->new_cpl_strategy;
+
+        if (!blk || (block->cpl_in_use && !got_cpl_snr)) {
+            block->new_snr_offsets = 1;
+            if (block->cpl_in_use)
+                got_cpl_snr = 1;
+        } else {
+            block->new_snr_offsets = 0;
+        }
+    }
+
+    /* set bandwidth for each channel */
+    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        AC3Block *block = &s->blocks[blk];
+        for (ch = 1; ch <= s->fbw_channels; ch++) {
+            if (block->channel_in_cpl[ch])
+                block->end_freq[ch] = s->start_freq[CPL_CH];
+            else
+                block->end_freq[ch] = s->bandwidth_code * 3 + 73;
+        }
+    }
+}
+
+
+/**
+ * Calculate a single coupling coordinate.
+ */
+static inline float calc_cpl_coord(float energy_ch, float energy_cpl)
+{
+    float coord = 0.125;
+    if (energy_cpl > 0)
+        coord *= sqrtf(energy_ch / energy_cpl);
+    return coord;
+}
+
+
+/**
+ * Calculate coupling channel and coupling coordinates.
+ * TODO: Currently this is only used for the floating-point encoder. I was
+ *       able to make it work for the fixed-point encoder, but quality was
+ *       generally lower in most cases than not using coupling. If a more
+ *       adaptive coupling strategy were to be implemented it might be useful
+ *       at that time to use coupling for the fixed-point encoder as well.
+ */
+static void apply_channel_coupling(AC3EncodeContext *s)
+{
+#if CONFIG_AC3ENC_FLOAT
+    DECLARE_ALIGNED(16, float,   cpl_coords)      [AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16];
+    DECLARE_ALIGNED(16, int32_t, fixed_cpl_coords)[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16];
+    int blk, ch, bnd, i, j;
+    CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
+    int num_cpl_coefs = s->num_cpl_subbands * 12;
+
+    /* calculate coupling channel from fbw channels */
+    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        AC3Block *block = &s->blocks[blk];
+        CoefType *cpl_coef = &block->mdct_coef[CPL_CH][s->start_freq[CPL_CH]];
+        if (!block->cpl_in_use)
+            continue;
+        memset(cpl_coef-1, 0, (num_cpl_coefs+4) * sizeof(*cpl_coef));
+        for (ch = 1; ch <= s->fbw_channels; ch++) {
+            CoefType *ch_coef = &block->mdct_coef[ch][s->start_freq[CPL_CH]];
+            if (!block->channel_in_cpl[ch])
+                continue;
+            for (i = 0; i < num_cpl_coefs; i++)
+                cpl_coef[i] += ch_coef[i];
+        }
+        /* note: coupling start bin % 4 will always be 1 and num_cpl_coefs
+                 will always be a multiple of 12, so we need to subtract 1 from
+                 the start and add 4 to the length when using optimized
+                 functions which require 16-byte alignment. */
+
+        /* coefficients must be clipped to +/- 1.0 in order to be encoded */
+        s->dsp.vector_clipf(cpl_coef-1, cpl_coef-1, -1.0f, 1.0f, num_cpl_coefs+4);
+
+        /* scale coupling coefficients from float to 24-bit fixed-point */
+        s->ac3dsp.float_to_fixed24(&block->fixed_coef[CPL_CH][s->start_freq[CPL_CH]-1],
+                                   cpl_coef-1, num_cpl_coefs+4);
+    }
+
+    /* calculate energy in each band in coupling channel and each fbw channel */
+    /* TODO: possibly use SIMD to speed up energy calculation */
+    bnd = 0;
+    i = s->start_freq[CPL_CH];
+    while (i < s->cpl_end_freq) {
+        int band_size = s->cpl_band_sizes[bnd];
+        for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
+            for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+                AC3Block *block = &s->blocks[blk];
+                if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
+                    continue;
+                for (j = 0; j < band_size; j++) {
+                    CoefType v = block->mdct_coef[ch][i+j];
+                    MAC_COEF(energy[blk][ch][bnd], v, v);
+                }
+            }
+        }
+        i += band_size;
+        bnd++;
+    }
+
+    /* determine which blocks to send new coupling coordinates for */
+    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        AC3Block *block  = &s->blocks[blk];
+        AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
+        int new_coords = 0;
+        CoefSumType coord_diff[AC3_MAX_CHANNELS] = {0,};
+
+        if (block->cpl_in_use) {
+            /* calculate coupling coordinates for all blocks and calculate the
+               average difference between coordinates in successive blocks */
+            for (ch = 1; ch <= s->fbw_channels; ch++) {
+                if (!block->channel_in_cpl[ch])
+                    continue;
+
+                for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
+                    cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
+                                                              energy[blk][CPL_CH][bnd]);
+                    if (blk > 0 && block0->cpl_in_use &&
+                        block0->channel_in_cpl[ch]) {
+                        coord_diff[ch] += fabs(cpl_coords[blk-1][ch][bnd] -
+                                               cpl_coords[blk  ][ch][bnd]);
+                    }
+                }
+                coord_diff[ch] /= s->num_cpl_bands;
+            }
+
+            /* send new coordinates if this is the first block, if previous
+             * block did not use coupling but this block does, the channels
+             * using coupling has changed from the previous block, or the
+             * coordinate difference from the last block for any channel is
+             * greater than a threshold value. */
+            if (blk == 0) {
+                new_coords = 1;
+            } else if (!block0->cpl_in_use) {
+                new_coords = 1;
+            } else {
+                for (ch = 1; ch <= s->fbw_channels; ch++) {
+                    if (block->channel_in_cpl[ch] && !block0->channel_in_cpl[ch]) {
+                        new_coords = 1;
+                        break;
+                    }
+                }
+                if (!new_coords) {
+                    for (ch = 1; ch <= s->fbw_channels; ch++) {
+                        if (block->channel_in_cpl[ch] && coord_diff[ch] > 0.04) {
+                            new_coords = 1;
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+        block->new_cpl_coords = new_coords;
+    }
+
+    /* calculate final coupling coordinates, taking into account reusing of
+       coordinates in successive blocks */
+    for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
+        blk = 0;
+        while (blk < AC3_MAX_BLOCKS) {
+            int blk1;
+            CoefSumType energy_cpl;
+            AC3Block *block  = &s->blocks[blk];
+
+            if (!block->cpl_in_use) {
+                blk++;
+                continue;
+            }
+
+            energy_cpl = energy[blk][CPL_CH][bnd];
+            blk1 = blk+1;
+            while (!s->blocks[blk1].new_cpl_coords && blk1 < AC3_MAX_BLOCKS) {
+                if (s->blocks[blk1].cpl_in_use)
+                    energy_cpl += energy[blk1][CPL_CH][bnd];
+                blk1++;
+            }
+
+            for (ch = 1; ch <= s->fbw_channels; ch++) {
+                CoefType energy_ch;
+                if (!block->channel_in_cpl[ch])
+                    continue;
+                energy_ch = energy[blk][ch][bnd];
+                blk1 = blk+1;
+                while (!s->blocks[blk1].new_cpl_coords && blk1 < AC3_MAX_BLOCKS) {
+                    if (s->blocks[blk1].cpl_in_use)
+                        energy_ch += energy[blk1][ch][bnd];
+                    blk1++;
+                }
+                cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
+            }
+            blk = blk1;
+        }
+    }
+
+    /* calculate exponents/mantissas for coupling coordinates */
+    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        AC3Block *block = &s->blocks[blk];
+        if (!block->cpl_in_use || !block->new_cpl_coords)
+            continue;
+
+        s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
+                                   cpl_coords[blk][1],
+                                   s->fbw_channels * 16);
+        s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
+                                    fixed_cpl_coords[blk][1],
+                                    s->fbw_channels * 16);
+
+        for (ch = 1; ch <= s->fbw_channels; ch++) {
+            int bnd, min_exp, max_exp, master_exp;
+
+            /* determine master exponent */
+            min_exp = max_exp = block->cpl_coord_exp[ch][0];
+            for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
+                int exp = block->cpl_coord_exp[ch][bnd];
+                min_exp = FFMIN(exp, min_exp);
+                max_exp = FFMAX(exp, max_exp);
+            }
+            master_exp = ((max_exp - 15) + 2) / 3;
+            master_exp = FFMAX(master_exp, 0);
+            while (min_exp < master_exp * 3)
+                master_exp--;
+            for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
+                block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
+                                                        master_exp * 3, 0, 15);
+            }
+            block->cpl_master_exp[ch] = master_exp;
+
+            /* quantize mantissas */
+            for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
+                int cpl_exp  = block->cpl_coord_exp[ch][bnd];
+                int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
+                if (cpl_exp == 15)
+                    cpl_mant >>= 1;
+                else
+                    cpl_mant -= 16;
+
+                block->cpl_coord_mant[ch][bnd] = cpl_mant;
+            }
+        }
+    }
+#endif /* CONFIG_AC3ENC_FLOAT */
+}
+
+
 /**
  * Determine rematrixing flags for each block and band.
  */
@@ -440,23 +793,32 @@ static void compute_rematrixing_strategy(AC3EncodeContext *s)
     if (s->channel_mode != AC3_CHMODE_STEREO)
         return;
 
-    s->num_rematrixing_bands = 4;
-
-    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
-
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         block = &s->blocks[blk];
         block->new_rematrixing_strategy = !blk;
-        if (!s->rematrixing_enabled)
+
+        if (!s->rematrixing_enabled) {
+            block0 = block;
             continue;
-        for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
+        }
+
+        block->num_rematrixing_bands = 4;
+        if (block->cpl_in_use) {
+            block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
+            block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
+            if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
+                block->new_rematrixing_strategy = 1;
+        }
+        nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
+
+        for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
             /* calculate calculate sum of squared coeffs for one band in one block */
             int start = ff_ac3_rematrix_band_tab[bnd];
             int end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
             CoefSumType sum[4] = {0,};
             for (i = start; i < end; i++) {
-                CoefType lt = block->mdct_coef[0][i];
-                CoefType rt = block->mdct_coef[1][i];
+                CoefType lt = block->mdct_coef[1][i];
+                CoefType rt = block->mdct_coef[2][i];
                 CoefType md = lt + rt;
                 CoefType sd = lt - rt;
                 MAC_COEF(sum[0], lt, lt);
@@ -495,21 +857,20 @@ static void apply_rematrixing(AC3EncodeContext *s)
     if (!s->rematrixing_enabled)
         return;
 
-    nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
-
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         AC3Block *block = &s->blocks[blk];
         if (block->new_rematrixing_strategy)
             flags = block->rematrixing_flags;
-        for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
+        nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
+        for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
             if (flags[bnd]) {
                 start = ff_ac3_rematrix_band_tab[bnd];
                 end   = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
                 for (i = start; i < end; i++) {
-                    int32_t lt = block->fixed_coef[0][i];
-                    int32_t rt = block->fixed_coef[1][i];
-                    block->fixed_coef[0][i] = (lt + rt) >> 1;
-                    block->fixed_coef[1][i] = (lt - rt) >> 1;
+                    int32_t lt = block->fixed_coef[1][i];
+                    int32_t rt = block->fixed_coef[2][i];
+                    block->fixed_coef[1][i] = (lt + rt) >> 1;
+                    block->fixed_coef[2][i] = (lt - rt) >> 1;
                 }
             }
         }
@@ -526,12 +887,13 @@ static av_cold void exponent_init(AC3EncodeContext *s)
 
     for (expstr = EXP_D15-1; expstr <= EXP_D45-1; expstr++) {
         grpsize = 3 << expstr;
-        for (i = 73; i < 256; i++) {
-            exponent_group_tab[expstr][i] = (i + grpsize - 4) / grpsize;
+        for (i = 12; i < 256; i++) {
+            exponent_group_tab[0][expstr][i] = (i + grpsize - 4) / grpsize;
+            exponent_group_tab[1][expstr][i] = (i              ) / grpsize;
         }
     }
     /* LFE */
-    exponent_group_tab[0][7] = 2;
+    exponent_group_tab[0][0][7] = 2;
 }
 
 
@@ -544,7 +906,7 @@ static void extract_exponents(AC3EncodeContext *s)
 {
     int blk, ch;
 
-    for (ch = 0; ch < s->channels; ch++) {
+    for (ch = !s->cpl_on; ch <= s->channels; ch++) {
         for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
             AC3Block *block = &s->blocks[blk];
             s->ac3dsp.extract_exponents(block->exp[ch], block->fixed_coef[ch],
@@ -569,7 +931,7 @@ static void compute_exp_strategy(AC3EncodeContext *s)
 {
     int ch, blk, blk1;
 
-    for (ch = 0; ch < s->fbw_channels; ch++) {
+    for (ch = !s->cpl_on; ch <= s->fbw_channels; ch++) {
         uint8_t *exp_strategy = s->exp_strategy[ch];
         uint8_t *exp          = s->blocks[0].exp[ch];
         int exp_diff;
@@ -578,13 +940,18 @@ static void compute_exp_strategy(AC3EncodeContext *s)
            reused in the next frame */
         exp_strategy[0] = EXP_NEW;
         exp += AC3_MAX_COEFS;
-        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
+        for (blk = 1; blk < AC3_MAX_BLOCKS; blk++, exp += AC3_MAX_COEFS) {
+            if ((ch == CPL_CH && (!s->blocks[blk].cpl_in_use || !s->blocks[blk-1].cpl_in_use)) ||
+                (ch  > CPL_CH && (s->blocks[blk].channel_in_cpl[ch] != s->blocks[blk-1].channel_in_cpl[ch]))) {
+                exp_strategy[blk] = EXP_NEW;
+                continue;
+            }
             exp_diff = s->dsp.sad[0](NULL, exp, exp - AC3_MAX_COEFS, 16, 16);
-            if (exp_diff > EXP_DIFF_THRESHOLD)
+            exp_strategy[blk] = EXP_REUSE;
+            if (ch == CPL_CH && exp_diff > (EXP_DIFF_THRESHOLD * (s->blocks[blk].end_freq[ch] - s->start_freq[ch]) / AC3_MAX_COEFS))
+                exp_strategy[blk] = EXP_NEW;
+            else if (ch > CPL_CH && exp_diff > EXP_DIFF_THRESHOLD)
                 exp_strategy[blk] = EXP_NEW;
-            else
-                exp_strategy[blk] = EXP_REUSE;
-            exp += AC3_MAX_COEFS;
         }
 
         /* now select the encoding strategy type : if exponents are often
@@ -615,25 +982,26 @@ static void compute_exp_strategy(AC3EncodeContext *s)
 /**
  * Update the exponents so that they are the ones the decoder will decode.
  */
-static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
+static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy,
+                                    int cpl)
 {
     int nb_groups, i, k;
 
-    nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
+    nb_groups = exponent_group_tab[cpl][exp_strategy-1][nb_exps] * 3;
 
     /* for each group, compute the minimum exponent */
     switch(exp_strategy) {
     case EXP_D25:
-        for (i = 1, k = 1; i <= nb_groups; i++) {
+        for (i = 1, k = 1-cpl; i <= nb_groups; i++) {
             uint8_t exp_min = exp[k];
             if (exp[k+1] < exp_min)
                 exp_min = exp[k+1];
-            exp[i] = exp_min;
+            exp[i-cpl] = exp_min;
             k += 2;
         }
         break;
     case EXP_D45:
-        for (i = 1, k = 1; i <= nb_groups; i++) {
+        for (i = 1, k = 1-cpl; i <= nb_groups; i++) {
             uint8_t exp_min = exp[k];
             if (exp[k+1] < exp_min)
                 exp_min = exp[k+1];
@@ -641,14 +1009,14 @@ static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
                 exp_min = exp[k+2];
             if (exp[k+3] < exp_min)
                 exp_min = exp[k+3];
-            exp[i] = exp_min;
+            exp[i-cpl] = exp_min;
             k += 4;
         }
         break;
     }
 
     /* constraint for DC exponent */
-    if (exp[0] > 15)
+    if (!cpl && exp[0] > 15)
         exp[0] = 15;
 
     /* decrease the delta between each groups to within 2 so that they can be
@@ -659,18 +1027,21 @@ static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
     while (--i >= 0)
         exp[i] = FFMIN(exp[i], exp[i+1] + 2);
 
+    if (cpl)
+        exp[-1] = exp[0] & ~1;
+
     /* now we have the exponent values the decoder will see */
     switch (exp_strategy) {
     case EXP_D25:
-        for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
-            uint8_t exp1 = exp[i];
+        for (i = nb_groups, k = (nb_groups * 2)-cpl; i > 0; i--) {
+            uint8_t exp1 = exp[i-cpl];
             exp[k--] = exp1;
             exp[k--] = exp1;
         }
         break;
     case EXP_D45:
-        for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
-            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
+        for (i = nb_groups, k = (nb_groups * 4)-cpl; i > 0; i--) {
+            exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i-cpl];
             k -= 4;
         }
         break;
@@ -686,32 +1057,40 @@ static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
  */
 static void encode_exponents(AC3EncodeContext *s)
 {
-    int blk, blk1, ch;
+    int blk, blk1, ch, cpl;
     uint8_t *exp, *exp_strategy;
     int nb_coefs, num_reuse_blocks;
 
-    for (ch = 0; ch < s->channels; ch++) {
-        exp          = s->blocks[0].exp[ch];
+    for (ch = !s->cpl_on; ch <= s->channels; ch++) {
+        exp          = s->blocks[0].exp[ch] + s->start_freq[ch];
         exp_strategy = s->exp_strategy[ch];
-        nb_coefs     = s->nb_coefs[ch];
 
+        cpl = (ch == CPL_CH);
         blk = 0;
         while (blk < AC3_MAX_BLOCKS) {
+            AC3Block *block = &s->blocks[blk];
+            if (cpl && !block->cpl_in_use) {
+                exp += AC3_MAX_COEFS;
+                blk++;
+                continue;
+            }
+            nb_coefs = block->end_freq[ch] - s->start_freq[ch];
             blk1 = blk + 1;
 
             /* count the number of EXP_REUSE blocks after the current block
                and set exponent reference block pointers */
-            s->blocks[blk].exp_ref_block[ch] = &s->blocks[blk];
+            block->exp_ref_block[ch] = block;
             while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE) {
-                s->blocks[blk1].exp_ref_block[ch] = &s->blocks[blk];
+                s->blocks[blk1].exp_ref_block[ch] = block;
                 blk1++;
             }
             num_reuse_blocks = blk1 - blk - 1;
 
             /* for the EXP_REUSE case we select the min of the exponents */
-            s->ac3dsp.ac3_exponent_min(exp, num_reuse_blocks, nb_coefs);
+            s->ac3dsp.ac3_exponent_min(exp-s->start_freq[ch], num_reuse_blocks,
+                                       AC3_MAX_COEFS);
 
-            encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk]);
+            encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk], cpl);
 
             exp += AC3_MAX_COEFS * (num_reuse_blocks + 1);
             blk = blk1;
@@ -727,7 +1106,7 @@ static void encode_exponents(AC3EncodeContext *s)
  */
 static void group_exponents(AC3EncodeContext *s)
 {
-    int blk, ch, i;
+    int blk, ch, i, cpl;
     int group_size, nb_groups, bit_count;
     uint8_t *p;
     int delta0, delta1, delta2;
@@ -736,14 +1115,15 @@ static void group_exponents(AC3EncodeContext *s)
     bit_count = 0;
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         AC3Block *block = &s->blocks[blk];
-        for (ch = 0; ch < s->channels; ch++) {
+        for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
             int exp_strategy = s->exp_strategy[ch][blk];
             if (exp_strategy == EXP_REUSE)
                 continue;
+            cpl = (ch == CPL_CH);
             group_size = exp_strategy + (exp_strategy == EXP_D45);
-            nb_groups = exponent_group_tab[exp_strategy-1][s->nb_coefs[ch]];
+            nb_groups = exponent_group_tab[cpl][exp_strategy-1][block->end_freq[ch]-s->start_freq[ch]];
             bit_count += 4 + (nb_groups * 7);
-            p = block->exp[ch];
+            p = block->exp[ch] + s->start_freq[ch] - cpl;
 
             /* DC exponent */
             exp1 = *p++;
@@ -810,9 +1190,7 @@ static void count_frame_bits_fixed(AC3EncodeContext *s)
 
     /* assumptions:
      *   no dynamic range codes
-     *   no channel coupling
      *   bit allocation parameters do not change between blocks
-     *   SNR offsets do not change between blocks
      *   no delta bit allocation
      *   no skipped data
      *   no auxilliary data
@@ -833,11 +1211,6 @@ static void count_frame_bits_fixed(AC3EncodeContext *s)
         /* dynamic range */
         frame_bits++;
 
-        /* coupling strategy */
-        frame_bits++;
-        if (!blk)
-            frame_bits++;
-
         /* exponent strategy */
         frame_bits += 2 * s->fbw_channels;
         if (s->lfe_on)
@@ -848,11 +1221,6 @@ static void count_frame_bits_fixed(AC3EncodeContext *s)
         if (!blk)
             frame_bits += 2 + 2 + 2 + 2 + 3;
 
-        /* snr offsets and fast gain codes */
-        frame_bits++;
-        if (!blk)
-            frame_bits += 6 + s->channels * (4 + 3);
-
         /* delta bit allocation */
         frame_bits++;
 
@@ -884,7 +1252,7 @@ static void bit_alloc_init(AC3EncodeContext *s)
     s->slow_gain_code  = 1;
     s->db_per_bit_code = 3;
     s->floor_code      = 7;
-    for (ch = 0; ch < s->channels; ch++)
+    for (ch = 0; ch <= s->channels; ch++)
         s->fast_gain_code[ch] = 4;
 
     /* initial snr offset */
@@ -898,6 +1266,8 @@ static void bit_alloc_init(AC3EncodeContext *s)
     s->bit_alloc.slow_gain  = ff_ac3_slow_gain_tab[s->slow_gain_code];
     s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
     s->bit_alloc.floor      = ff_ac3_floor_tab[s->floor_code];
+    s->bit_alloc.cpl_fast_leak = 0;
+    s->bit_alloc.cpl_slow_leak = 0;
 
     count_frame_bits_fixed(s);
 }
@@ -926,17 +1296,64 @@ static void count_frame_bits(AC3EncodeContext *s)
 
     /* audio blocks */
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        AC3Block *block = &s->blocks[blk];
+
+        /* coupling strategy */
+        frame_bits++;
+        if (block->new_cpl_strategy) {
+            frame_bits++;
+            if (block->cpl_in_use) {
+                frame_bits += s->fbw_channels;
+                if (s->channel_mode == AC3_CHMODE_STEREO)
+                    frame_bits++;
+                frame_bits += 4 + 4;
+                frame_bits += s->num_cpl_subbands - 1;
+            }
+        }
+
+        /* coupling coordinates */
+        if (block->cpl_in_use) {
+            for (ch = 1; ch <= s->fbw_channels; ch++) {
+                if (block->channel_in_cpl[ch]) {
+                    frame_bits++;
+                    if (block->new_cpl_coords) {
+                        frame_bits += 2;
+                        frame_bits += (4 + 4) * s->num_cpl_bands;
+                    }
+                }
+            }
+        }
+
         /* stereo rematrixing */
         if (s->channel_mode == AC3_CHMODE_STEREO) {
             frame_bits++;
             if (s->blocks[blk].new_rematrixing_strategy)
-                frame_bits += s->num_rematrixing_bands;
+                frame_bits += block->num_rematrixing_bands;
         }
 
         /* bandwidth codes & gain range */
-        for (ch = 0; ch < s->fbw_channels; ch++) {
-            if (s->exp_strategy[ch][blk] != EXP_REUSE)
-                frame_bits += 6 + 2;
+        for (ch = 1; ch <= s->fbw_channels; ch++) {
+            if (s->exp_strategy[ch][blk] != EXP_REUSE) {
+                if (!block->channel_in_cpl[ch])
+                    frame_bits += 6;
+                frame_bits += 2;
+            }
+        }
+
+        /* coupling exponent strategy */
+        if (block->cpl_in_use)
+            frame_bits += 2;
+
+        /* snr offsets and fast gain codes */
+        frame_bits++;
+        if (block->new_snr_offsets)
+            frame_bits += 6 + (s->channels + block->cpl_in_use) * (4 + 3);
+
+        /* coupling leak info */
+        if (block->cpl_in_use) {
+            frame_bits++;
+            if (block->new_cpl_leak)
+                frame_bits += 3 + 3;
         }
     }
 
@@ -970,16 +1387,16 @@ static void bit_alloc_masking(AC3EncodeContext *s)
 
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         AC3Block *block = &s->blocks[blk];
-        for (ch = 0; ch < s->channels; ch++) {
+        for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
             /* We only need psd and mask for calculating bap.
                Since we currently do not calculate bap when exponent
                strategy is EXP_REUSE we do not need to calculate psd or mask. */
             if (s->exp_strategy[ch][blk] != EXP_REUSE) {
-                ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
-                                          s->nb_coefs[ch],
-                                          block->psd[ch], block->band_psd[ch]);
+                ff_ac3_bit_alloc_calc_psd(block->exp[ch], s->start_freq[ch],
+                                          block->end_freq[ch], block->psd[ch],
+                                          block->band_psd[ch]);
                 ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
-                                           0, s->nb_coefs[ch],
+                                           s->start_freq[ch], block->end_freq[ch],
                                            ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
                                            ch == s->lfe_channel,
                                            DBA_NONE, 0, NULL, NULL, NULL,
@@ -997,11 +1414,12 @@ static void bit_alloc_masking(AC3EncodeContext *s)
 static void reset_block_bap(AC3EncodeContext *s)
 {
     int blk, ch;
+    int channels = s->channels + 1;
     if (s->blocks[0].bap[0] == s->bap_buffer)
         return;
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
-        for (ch = 0; ch < s->channels; ch++) {
-            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
+        for (ch = 0; ch < channels; ch++) {
+            s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * channels + ch)];
         }
     }
 }
@@ -1027,28 +1445,37 @@ static int bit_alloc(AC3EncodeContext *s, int snr_offset)
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         AC3Block *block = &s->blocks[blk];
         AC3Block *ref_block;
+        int av_uninit(ch0);
+        int got_cpl = !block->cpl_in_use;
         // initialize grouped mantissa counts. these are set so that they are
         // padded to the next whole group size when bits are counted in
         // compute_mantissa_size_final
         mant_cnt[0] = mant_cnt[3] = 0;
         mant_cnt[1] = mant_cnt[2] = 2;
         mant_cnt[4] = 1;
-        for (ch = 0; ch < s->channels; ch++) {
+        for (ch = 1; ch <= s->channels; ch++) {
+            if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
+                ch0     = ch - 1;
+                ch      = CPL_CH;
+                got_cpl = 1;
+            }
+
             /* Currently the only bit allocation parameters which vary across
                blocks within a frame are the exponent values.  We can take
                advantage of that by reusing the bit allocation pointers
                whenever we reuse exponents. */
             ref_block = block->exp_ref_block[ch];
             if (s->exp_strategy[ch][blk] != EXP_REUSE) {
-                s->ac3dsp.bit_alloc_calc_bap(ref_block->mask[ch],
-                                             ref_block->psd[ch], 0,
-                                             s->nb_coefs[ch], snr_offset,
-                                             s->bit_alloc.floor, ff_ac3_bap_tab,
-                                             ref_block->bap[ch]);
+                s->ac3dsp.bit_alloc_calc_bap(ref_block->mask[ch], ref_block->psd[ch],
+                                             s->start_freq[ch], block->end_freq[ch],
+                                             snr_offset, s->bit_alloc.floor,
+                                             ff_ac3_bap_tab, ref_block->bap[ch]);
             }
             mantissa_bits += s->ac3dsp.compute_mantissa_size(mant_cnt,
-                                                             ref_block->bap[ch],
-                                                             s->nb_coefs[ch]);
+                                                             ref_block->bap[ch]+s->start_freq[ch],
+                                                             block->end_freq[ch]-s->start_freq[ch]);
+            if (ch == CPL_CH)
+                ch = ch0;
         }
         mantissa_bits += compute_mantissa_size_final(mant_cnt);
     }
@@ -1074,7 +1501,7 @@ static int cbr_bit_allocation(AC3EncodeContext *s)
 
     /* if previous frame SNR offset was 1023, check if current frame can also
        use SNR offset of 1023. if so, skip the search. */
-    if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
+    if ((snr_offset | s->fine_snr_offset[1]) == 1023) {
         if (bit_alloc(s, 1023) <= bits_left)
             return 0;
     }
@@ -1098,7 +1525,7 @@ static int cbr_bit_allocation(AC3EncodeContext *s)
     reset_block_bap(s);
 
     s->coarse_snr_offset = snr_offset >> 4;
-    for (ch = 0; ch < s->channels; ch++)
+    for (ch = !s->cpl_on; ch <= s->channels; ch++)
         s->fine_snr_offset[ch] = snr_offset & 0xF;
 
     return 0;
@@ -1116,26 +1543,26 @@ static int downgrade_exponents(AC3EncodeContext *s)
 {
     int ch, blk;
 
-    for (ch = 0; ch < s->fbw_channels; ch++) {
-        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
+    for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
+        for (ch = !s->blocks[blk].cpl_in_use; ch <= s->fbw_channels; ch++) {
             if (s->exp_strategy[ch][blk] == EXP_D15) {
                 s->exp_strategy[ch][blk] = EXP_D25;
                 return 0;
             }
         }
     }
-    for (ch = 0; ch < s->fbw_channels; ch++) {
-        for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
+    for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
+        for (ch = !s->blocks[blk].cpl_in_use; ch <= s->fbw_channels; ch++) {
             if (s->exp_strategy[ch][blk] == EXP_D25) {
                 s->exp_strategy[ch][blk] = EXP_D45;
                 return 0;
             }
         }
     }
-    for (ch = 0; ch < s->fbw_channels; ch++) {
-        /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
-           the block number > 0 */
-        for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
+    /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
+       the block number > 0 */
+    for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
+        for (ch = !s->blocks[blk].cpl_in_use; ch <= s->fbw_channels; ch++) {
             if (s->exp_strategy[ch][blk] > EXP_REUSE) {
                 s->exp_strategy[ch][blk] = EXP_REUSE;
                 return 0;
@@ -1162,7 +1589,18 @@ static int compute_bit_allocation(AC3EncodeContext *s)
 
     ret = cbr_bit_allocation(s);
     while (ret) {
-        /* fallback 1: downgrade exponents */
+        /* fallback 1: disable channel coupling */
+        if (s->cpl_on) {
+            s->cpl_on = 0;
+            compute_coupling_strategy(s);
+            compute_rematrixing_strategy(s);
+            apply_rematrixing(s);
+            process_exponents(s);
+            ret = compute_bit_allocation(s);
+            continue;
+        }
+
+        /* fallback 2: downgrade exponents */
         if (!downgrade_exponents(s)) {
             extract_exponents(s);
             encode_exponents(s);
@@ -1216,12 +1654,13 @@ static inline int asym_quant(int c, int e, int qbits)
  * Quantize a set of mantissas for a single channel in a single block.
  */
 static void quantize_mantissas_blk_ch(AC3Mant *s, int32_t *fixed_coef,
-                                      uint8_t *exp,
-                                      uint8_t *bap, uint16_t *qmant, int n)
+                                      uint8_t *exp, uint8_t *bap,
+                                      uint16_t *qmant, int start_freq,
+                                      int end_freq)
 {
     int i;
 
-    for (i = 0; i < n; i++) {
+    for (i = start_freq; i < end_freq; i++) {
         int v;
         int c = fixed_coef[i];
         int e = exp[i];
@@ -1311,19 +1750,27 @@ static void quantize_mantissas_blk_ch(AC3Mant *s, int32_t *fixed_coef,
  */
 static void quantize_mantissas(AC3EncodeContext *s)
 {
-    int blk, ch;
-
+    int blk, ch, ch0=0, got_cpl;
 
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         AC3Block *block = &s->blocks[blk];
         AC3Block *ref_block;
         AC3Mant m = { 0 };
 
-        for (ch = 0; ch < s->channels; ch++) {
+        got_cpl = !block->cpl_in_use;
+        for (ch = 1; ch <= s->channels; ch++) {
+            if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
+                ch0     = ch - 1;
+                ch      = CPL_CH;
+                got_cpl = 1;
+            }
             ref_block = block->exp_ref_block[ch];
             quantize_mantissas_blk_ch(&m, block->fixed_coef[ch],
-                                      ref_block->exp[ch], ref_block->bap[ch],
-                                      block->qmant[ch], s->nb_coefs[ch]);
+                                      ref_block->exp[ch],
+                                      ref_block->bap[ch], block->qmant[ch],
+                                      s->start_freq[ch], block->end_freq[ch]);
+            if (ch == CPL_CH)
+                ch = ch0;
         }
     }
 }
@@ -1390,7 +1837,8 @@ static void output_frame_header(AC3EncodeContext *s)
  */
 static void output_audio_block(AC3EncodeContext *s, int blk)
 {
-    int ch, i, baie, rbnd;
+    int ch, i, baie, bnd, got_cpl;
+    int av_uninit(ch0);
     AC3Block *block = &s->blocks[blk];
 
     /* block switching */
@@ -1405,11 +1853,38 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
     put_bits(&s->pb, 1, 0);
 
     /* channel coupling */
-    if (!blk) {
-        put_bits(&s->pb, 1, 1); /* coupling strategy present */
-        put_bits(&s->pb, 1, 0); /* no coupling strategy */
-    } else {
-        put_bits(&s->pb, 1, 0); /* no new coupling strategy */
+    put_bits(&s->pb, 1, block->new_cpl_strategy);
+    if (block->new_cpl_strategy) {
+        put_bits(&s->pb, 1, block->cpl_in_use);
+        if (block->cpl_in_use) {
+            int start_sub, end_sub;
+            for (ch = 1; ch <= s->fbw_channels; ch++)
+                put_bits(&s->pb, 1, block->channel_in_cpl[ch]);
+            if (s->channel_mode == AC3_CHMODE_STEREO)
+                put_bits(&s->pb, 1, 0); /* phase flags in use */
+            start_sub = (s->start_freq[CPL_CH] - 37) / 12;
+            end_sub   = (s->cpl_end_freq       - 37) / 12;
+            put_bits(&s->pb, 4, start_sub);
+            put_bits(&s->pb, 4, end_sub - 3);
+            for (bnd = start_sub+1; bnd < end_sub; bnd++)
+                put_bits(&s->pb, 1, ff_eac3_default_cpl_band_struct[bnd]);
+        }
+    }
+
+    /* coupling coordinates */
+    if (block->cpl_in_use) {
+        for (ch = 1; ch <= s->fbw_channels; ch++) {
+            if (block->channel_in_cpl[ch]) {
+                put_bits(&s->pb, 1, block->new_cpl_coords);
+                if (block->new_cpl_coords) {
+                    put_bits(&s->pb, 2, block->cpl_master_exp[ch]);
+                    for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
+                        put_bits(&s->pb, 4, block->cpl_coord_exp [ch][bnd]);
+                        put_bits(&s->pb, 4, block->cpl_coord_mant[ch][bnd]);
+                    }
+                }
+            }
+        }
     }
 
     /* stereo rematrixing */
@@ -1417,40 +1892,41 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
         put_bits(&s->pb, 1, block->new_rematrixing_strategy);
         if (block->new_rematrixing_strategy) {
             /* rematrixing flags */
-            for (rbnd = 0; rbnd < s->num_rematrixing_bands; rbnd++)
-                put_bits(&s->pb, 1, block->rematrixing_flags[rbnd]);
+            for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++)
+                put_bits(&s->pb, 1, block->rematrixing_flags[bnd]);
         }
     }
 
     /* exponent strategy */
-    for (ch = 0; ch < s->fbw_channels; ch++)
+    for (ch = !block->cpl_in_use; ch <= s->fbw_channels; ch++)
         put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
     if (s->lfe_on)
         put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
 
     /* bandwidth */
-    for (ch = 0; ch < s->fbw_channels; ch++) {
-        if (s->exp_strategy[ch][blk] != EXP_REUSE)
+    for (ch = 1; ch <= s->fbw_channels; ch++) {
+        if (s->exp_strategy[ch][blk] != EXP_REUSE && !block->channel_in_cpl[ch])
             put_bits(&s->pb, 6, s->bandwidth_code);
     }
 
     /* exponents */
-    for (ch = 0; ch < s->channels; ch++) {
+    for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
         int nb_groups;
+        int cpl = (ch == CPL_CH);
 
         if (s->exp_strategy[ch][blk] == EXP_REUSE)
             continue;
 
         /* DC exponent */
-        put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
+        put_bits(&s->pb, 4, block->grouped_exp[ch][0] >> cpl);
 
         /* exponent groups */
-        nb_groups = exponent_group_tab[s->exp_strategy[ch][blk]-1][s->nb_coefs[ch]];
+        nb_groups = exponent_group_tab[cpl][s->exp_strategy[ch][blk]-1][block->end_freq[ch]-s->start_freq[ch]];
         for (i = 1; i <= nb_groups; i++)
             put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
 
         /* gain range info */
-        if (ch != s->lfe_channel)
+        if (ch != s->lfe_channel && !cpl)
             put_bits(&s->pb, 2, 0);
     }
 
@@ -1466,23 +1942,40 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
     }
 
     /* snr offset */
-    put_bits(&s->pb, 1, baie);
-    if (baie) {
+    put_bits(&s->pb, 1, block->new_snr_offsets);
+    if (block->new_snr_offsets) {
         put_bits(&s->pb, 6, s->coarse_snr_offset);
-        for (ch = 0; ch < s->channels; ch++) {
+        for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
             put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
             put_bits(&s->pb, 3, s->fast_gain_code[ch]);
         }
     }
 
+    /* coupling leak */
+    if (block->cpl_in_use) {
+        put_bits(&s->pb, 1, block->new_cpl_leak);
+        if (block->new_cpl_leak) {
+            put_bits(&s->pb, 3, s->bit_alloc.cpl_fast_leak);
+            put_bits(&s->pb, 3, s->bit_alloc.cpl_slow_leak);
+        }
+    }
+
     put_bits(&s->pb, 1, 0); /* no delta bit allocation */
     put_bits(&s->pb, 1, 0); /* no data to skip */
 
     /* mantissas */
-    for (ch = 0; ch < s->channels; ch++) {
+    got_cpl = !block->cpl_in_use;
+    for (ch = 1; ch <= s->channels; ch++) {
         int b, q;
-        AC3Block *ref_block = block->exp_ref_block[ch];
-        for (i = 0; i < s->nb_coefs[ch]; i++) {
+        AC3Block *ref_block;
+
+        if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
+            ch0     = ch - 1;
+            ch      = CPL_CH;
+            got_cpl = 1;
+        }
+        ref_block = block->exp_ref_block[ch];
+        for (i = s->start_freq[ch]; i < block->end_freq[ch]; i++) {
             q = block->qmant[ch][i];
             b = ref_block->bap[ch][i];
             switch (b) {
@@ -1496,6 +1989,8 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
             default:              put_bits(&s->pb, b-1, q); break;
             }
         }
+        if (ch == CPL_CH)
+            ch = ch0;
     }
 }
 
@@ -1881,6 +2376,12 @@ static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
 
     scale_coefficients(s);
 
+    s->cpl_on = s->cpl_enabled;
+    compute_coupling_strategy(s);
+
+    if (s->cpl_on)
+        apply_channel_coupling(s);
+
     compute_rematrixing_strategy(s);
 
     apply_rematrixing(s);
@@ -1961,7 +2462,7 @@ static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
     s->lfe_on       = !!(ch_layout & AV_CH_LOW_FREQUENCY);
     s->channels     = channels;
     s->fbw_channels = channels - s->lfe_on;
-    s->lfe_channel  = s->lfe_on ? s->fbw_channels : -1;
+    s->lfe_channel  = s->lfe_on ? s->fbw_channels + 1 : -1;
     if (s->lfe_on)
         ch_layout -= AV_CH_LOW_FREQUENCY;
 
@@ -2060,6 +2561,10 @@ static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
     s->rematrixing_enabled = s->options.stereo_rematrixing &&
                              (s->channel_mode == AC3_CHMODE_STEREO);
 
+    s->cpl_enabled = s->options.channel_coupling &&
+                     s->channel_mode >= AC3_CHMODE_STEREO &&
+                     CONFIG_AC3ENC_FLOAT;
+
     return 0;
 }
 
@@ -2071,7 +2576,8 @@ static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
  */
 static av_cold void set_bandwidth(AC3EncodeContext *s)
 {
-    int ch;
+    int blk, ch;
+    int av_uninit(cpl_start);
 
     if (s->cutoff) {
         /* calculate bandwidth based on user-specified cutoff frequency */
@@ -2084,11 +2590,54 @@ static av_cold void set_bandwidth(AC3EncodeContext *s)
     }
 
     /* set number of coefficients for each channel */
-    for (ch = 0; ch < s->fbw_channels; ch++) {
-        s->nb_coefs[ch] = s->bandwidth_code * 3 + 73;
+    for (ch = 1; ch <= s->fbw_channels; ch++) {
+        s->start_freq[ch] = 0;
+        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
+            s->blocks[blk].end_freq[ch] = s->bandwidth_code * 3 + 73;
+    }
+    /* LFE channel always has 7 coefs */
+    if (s->lfe_on) {
+        s->start_freq[s->lfe_channel] = 0;
+        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
+            s->blocks[blk].end_freq[ch] = 7;
+    }
+
+    /* initialize coupling strategy */
+    if (s->cpl_enabled) {
+        if (s->options.cpl_start >= 0) {
+            cpl_start = s->options.cpl_start;
+        } else {
+            cpl_start = ac3_coupling_start_tab[s->channel_mode-2][s->bit_alloc.sr_code][s->frame_size_code/2];
+            if (cpl_start < 0)
+                s->cpl_enabled = 0;
+        }
+    }
+    if (s->cpl_enabled) {
+        int i, cpl_start_band, cpl_end_band;
+        uint8_t *cpl_band_sizes = s->cpl_band_sizes;
+
+        cpl_end_band   = s->bandwidth_code / 4 + 3;
+        cpl_start_band = av_clip(cpl_start, 0, FFMIN(cpl_end_band-1, 15));
+
+        s->num_cpl_subbands = cpl_end_band - cpl_start_band;
+
+        s->num_cpl_bands = 1;
+        *cpl_band_sizes  = 12;
+        for (i = cpl_start_band + 1; i < cpl_end_band; i++) {
+            if (ff_eac3_default_cpl_band_struct[i]) {
+                *cpl_band_sizes += 12;
+            } else {
+                s->num_cpl_bands++;
+                cpl_band_sizes++;
+                *cpl_band_sizes = 12;
+            }
+        }
+
+        s->start_freq[CPL_CH] = cpl_start_band * 12 + 37;
+        s->cpl_end_freq       = cpl_end_band   * 12 + 37;
+        for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
+            s->blocks[blk].end_freq[CPL_CH] = s->cpl_end_freq;
     }
-    if (s->lfe_on)
-        s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
 }
 
 
@@ -2096,6 +2645,7 @@ static av_cold int allocate_buffers(AVCodecContext *avctx)
 {
     int blk, ch;
     AC3EncodeContext *s = avctx->priv_data;
+    int channels = s->channels + 1; /* includes coupling channel */
 
     FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
                      alloc_fail);
@@ -2104,74 +2654,90 @@ static av_cold int allocate_buffers(AVCodecContext *avctx)
                           (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
                           alloc_fail);
     }
-    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->bap_buffer,  AC3_MAX_BLOCKS * channels *
                      AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * channels *
                      AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * channels *
                      AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * channels *
                      AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * channels *
                      128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * channels *
                      AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * channels *
                      64 * sizeof(*s->band_psd_buffer), alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * channels *
                      64 * sizeof(*s->mask_buffer), alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
+    FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * channels *
                      AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
+    if (s->cpl_enabled) {
+        FF_ALLOC_OR_GOTO(avctx, s->cpl_coord_exp_buffer, AC3_MAX_BLOCKS * channels *
+                         16 * sizeof(*s->cpl_coord_exp_buffer), alloc_fail);
+        FF_ALLOC_OR_GOTO(avctx, s->cpl_coord_mant_buffer, AC3_MAX_BLOCKS * channels *
+                         16 * sizeof(*s->cpl_coord_mant_buffer), alloc_fail);
+    }
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         AC3Block *block = &s->blocks[blk];
-        FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
+        FF_ALLOC_OR_GOTO(avctx, block->bap, channels * sizeof(*block->bap),
                          alloc_fail);
-        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
+        FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, channels * sizeof(*block->mdct_coef),
                           alloc_fail);
-        FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
+        FF_ALLOCZ_OR_GOTO(avctx, block->exp, channels * sizeof(*block->exp),
                           alloc_fail);
-        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
+        FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, channels * sizeof(*block->grouped_exp),
                           alloc_fail);
-        FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
+        FF_ALLOCZ_OR_GOTO(avctx, block->psd, channels * sizeof(*block->psd),
                           alloc_fail);
-        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
+        FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, channels * sizeof(*block->band_psd),
                           alloc_fail);
-        FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
+        FF_ALLOCZ_OR_GOTO(avctx, block->mask, channels * sizeof(*block->mask),
                           alloc_fail);
-        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
+        FF_ALLOCZ_OR_GOTO(avctx, block->qmant, channels * sizeof(*block->qmant),
                           alloc_fail);
+        if (s->cpl_enabled) {
+            FF_ALLOCZ_OR_GOTO(avctx, block->cpl_coord_exp, channels * sizeof(*block->cpl_coord_exp),
+                              alloc_fail);
+            FF_ALLOCZ_OR_GOTO(avctx, block->cpl_coord_mant, channels * sizeof(*block->cpl_coord_mant),
+                              alloc_fail);
+        }
 
-        for (ch = 0; ch < s->channels; ch++) {
+        for (ch = 0; ch < channels; ch++) {
             /* arrangement: block, channel, coeff */
-            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
-            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (blk * s->channels + ch)];
-            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * s->channels + ch)];
-            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * s->channels + ch)];
-            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * s->channels + ch)];
-            block->mask[ch]        = &s->mask_buffer       [64            * (blk * s->channels + ch)];
-            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * s->channels + ch)];
+            block->bap[ch]         = &s->bap_buffer        [AC3_MAX_COEFS * (blk * channels + ch)];
+            block->grouped_exp[ch] = &s->grouped_exp_buffer[128           * (blk * channels + ch)];
+            block->psd[ch]         = &s->psd_buffer        [AC3_MAX_COEFS * (blk * channels + ch)];
+            block->band_psd[ch]    = &s->band_psd_buffer   [64            * (blk * channels + ch)];
+            block->mask[ch]        = &s->mask_buffer       [64            * (blk * channels + ch)];
+            block->qmant[ch]       = &s->qmant_buffer      [AC3_MAX_COEFS * (blk * channels + ch)];
+            if (s->cpl_enabled) {
+                block->cpl_coord_exp[ch]  = &s->cpl_coord_exp_buffer [16  * (blk * channels + ch)];
+                block->cpl_coord_mant[ch] = &s->cpl_coord_mant_buffer[16  * (blk * channels + ch)];
+            }
 
             /* arrangement: channel, block, coeff */
             block->exp[ch]         = &s->exp_buffer        [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
+            block->mdct_coef[ch]   = &s->mdct_coef_buffer  [AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
         }
     }
 
     if (CONFIG_AC3ENC_FLOAT) {
-        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
+        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * channels *
                          AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
         for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
             AC3Block *block = &s->blocks[blk];
-            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
+            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, channels *
                               sizeof(*block->fixed_coef), alloc_fail);
-            for (ch = 0; ch < s->channels; ch++)
-                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
+            for (ch = 0; ch < channels; ch++)
+                block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (AC3_MAX_BLOCKS * ch + blk)];
         }
     } else {
         for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
             AC3Block *block = &s->blocks[blk];
-            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
+            FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, channels *
                               sizeof(*block->fixed_coef), alloc_fail);
-            for (ch = 0; ch < s->channels; ch++)
+            for (ch = 0; ch < channels; ch++)
                 block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
         }
     }