src/opus_multistream_encoder.c

/* Copyright (c) 2011 Xiph.Org Foundation
   Written by Jean-Marc Valin */
/*
   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   - Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   - Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "opus_multistream.h"
#include "opus.h"
#include "opus_private.h"
#include "stack_alloc.h"
#include <stdarg.h>
#include "float_cast.h"
#include "os_support.h"
#include "mathops.h"
#include "mdct.h"
#include "modes.h"
#include "bands.h"
#include "quant_bands.h"
#include "pitch.h"

typedef struct {
   int nb_streams;
   int nb_coupled_streams;
   unsigned char mapping[8];
} VorbisLayout;

/* Index is nb_channel-1*/
static const VorbisLayout vorbis_mappings[8] = {
      {1, 0, {0}},                      /* 1: mono */
      {1, 1, {0, 1}},                   /* 2: stereo */
      {2, 1, {0, 2, 1}},                /* 3: 1-d surround */
      {2, 2, {0, 1, 2, 3}},             /* 4: quadraphonic surround */
      {3, 2, {0, 4, 1, 2, 3}},          /* 5: 5-channel surround */
      {4, 2, {0, 4, 1, 2, 3, 5}},       /* 6: 5.1 surround */
      {4, 3, {0, 4, 1, 2, 3, 5, 6}},    /* 7: 6.1 surround */
      {5, 3, {0, 6, 1, 2, 3, 4, 5, 7}}, /* 8: 7.1 surround */
};

typedef void (*opus_copy_channel_in_func)(
  opus_val16 *dst,
  int dst_stride,
  const void *src,
  int src_stride,
  int src_channel,
  int frame_size
);

typedef enum {
  MAPPING_TYPE_NONE,
  MAPPING_TYPE_SURROUND
#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
  ,  /* Do not include comma at end of enumerator list */
  MAPPING_TYPE_AMBISONICS
#endif
} MappingType;

struct OpusMSEncoder {
   ChannelLayout layout;
   int arch;
   int lfe_stream;
   int application;
   int variable_duration;
   MappingType mapping_type;
   opus_int32 bitrate_bps;
   /* Encoder states go here */
   /* then opus_val32 window_mem[channels*120]; */
   /* then opus_val32 preemph_mem[channels]; */
};

static opus_val32 *ms_get_preemph_mem(OpusMSEncoder *st)
{
   int s;
   char *ptr;
   int coupled_size, mono_size;

   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);
   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   for (s=0;s<st->layout.nb_streams;s++)
   {
      if (s < st->layout.nb_coupled_streams)
         ptr += align(coupled_size);
      else
         ptr += align(mono_size);
   }
   /* void* cast avoids clang -Wcast-align warning */
   return (opus_val32*)(void*)(ptr+st->layout.nb_channels*120*sizeof(opus_val32));
}

static opus_val32 *ms_get_window_mem(OpusMSEncoder *st)
{
   int s;
   char *ptr;
   int coupled_size, mono_size;

   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);
   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   for (s=0;s<st->layout.nb_streams;s++)
   {
      if (s < st->layout.nb_coupled_streams)
         ptr += align(coupled_size);
      else
         ptr += align(mono_size);
   }
   /* void* cast avoids clang -Wcast-align warning */
   return (opus_val32*)(void*)ptr;
}

#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
static int validate_ambisonics(int nb_channels, int *nb_streams, int *nb_coupled_streams)
{
   int order_plus_one;
   int acn_channels;
   int nondiegetic_channels;

   order_plus_one = isqrt32(nb_channels);
   acn_channels = order_plus_one * order_plus_one;
   nondiegetic_channels = nb_channels - acn_channels;

   if (order_plus_one < 1 || order_plus_one > 15 ||
       (nondiegetic_channels != 0 && nondiegetic_channels != 2))
      return 0;

   if (nb_streams)
      *nb_streams = acn_channels + (nondiegetic_channels != 0);
   if (nb_coupled_streams)
      *nb_coupled_streams = nondiegetic_channels != 0;
   return 1;
}
#endif

static int validate_encoder_layout(const ChannelLayout *layout)
{
   int s;
   for (s=0;s<layout->nb_streams;s++)
   {
      if (s < layout->nb_coupled_streams)
      {
         if (get_left_channel(layout, s, -1)==-1)
            return 0;
         if (get_right_channel(layout, s, -1)==-1)
            return 0;
      } else {
         if (get_mono_channel(layout, s, -1)==-1)
            return 0;
      }
   }
   return 1;
}

static void channel_pos(int channels, int pos[8])
{
   /* Position in the mix: 0 don't mix, 1: left, 2: center, 3:right */
   if (channels==4)
   {
      pos[0]=1;
      pos[1]=3;
      pos[2]=1;
      pos[3]=3;
   } else if (channels==3||channels==5||channels==6)
   {
      pos[0]=1;
      pos[1]=2;
      pos[2]=3;
      pos[3]=1;
      pos[4]=3;
      pos[5]=0;
   } else if (channels==7)
   {
      pos[0]=1;
      pos[1]=2;
      pos[2]=3;
      pos[3]=1;
      pos[4]=3;
      pos[5]=2;
      pos[6]=0;
   } else if (channels==8)
   {
      pos[0]=1;
      pos[1]=2;
      pos[2]=3;
      pos[3]=1;
      pos[4]=3;
      pos[5]=1;
      pos[6]=3;
      pos[7]=0;
   }
}

#if 1
/* Computes a rough approximation of log2(2^a + 2^b) */
static opus_val16 logSum(opus_val16 a, opus_val16 b)
{
   opus_val16 max;
   opus_val32 diff;
   opus_val16 frac;
   static const opus_val16 diff_table[17] = {
         QCONST16(0.5000000f, DB_SHIFT), QCONST16(0.2924813f, DB_SHIFT), QCONST16(0.1609640f, DB_SHIFT), QCONST16(0.0849625f, DB_SHIFT),
         QCONST16(0.0437314f, DB_SHIFT), QCONST16(0.0221971f, DB_SHIFT), QCONST16(0.0111839f, DB_SHIFT), QCONST16(0.0056136f, DB_SHIFT),
         QCONST16(0.0028123f, DB_SHIFT)
   };
   int low;
   if (a>b)
   {
      max = a;
      diff = SUB32(EXTEND32(a),EXTEND32(b));
   } else {
      max = b;
      diff = SUB32(EXTEND32(b),EXTEND32(a));
   }
   if (!(diff < QCONST16(8.f, DB_SHIFT)))  /* inverted to catch NaNs */
      return max;
#ifdef FIXED_POINT
   low = SHR32(diff, DB_SHIFT-1);
   frac = SHL16(diff - SHL16(low, DB_SHIFT-1), 16-DB_SHIFT);
#else
   low = (int)floor(2*diff);
   frac = 2*diff - low;
#endif
   return max + diff_table[low] + MULT16_16_Q15(frac, SUB16(diff_table[low+1], diff_table[low]));
}
#else
opus_val16 logSum(opus_val16 a, opus_val16 b)
{
   return log2(pow(4, a)+ pow(4, b))/2;
}
#endif

void surround_analysis(const CELTMode *celt_mode, const void *pcm, opus_val16 *bandLogE, opus_val32 *mem, opus_val32 *preemph_mem,
      int len, int overlap, int channels, int rate, opus_copy_channel_in_func copy_channel_in, int arch
)
{
   int c;
   int i;
   int LM;
   int pos[8] = {0};
   int upsample;
   int frame_size;
   int freq_size;
   opus_val16 channel_offset;
   opus_val32 bandE[21];
   opus_val16 maskLogE[3][21];
   VARDECL(opus_val32, in);
   VARDECL(opus_val16, x);
   VARDECL(opus_val32, freq);
   SAVE_STACK;

   upsample = resampling_factor(rate);
   frame_size = len*upsample;
   freq_size = IMIN(960, frame_size);

   /* LM = log2(frame_size / 120) */
   for (LM=0;LM<celt_mode->maxLM;LM++)
      if (celt_mode->shortMdctSize<<LM==frame_size)
         break;

   ALLOC(in, frame_size+overlap, opus_val32);
   ALLOC(x, len, opus_val16);
   ALLOC(freq, freq_size, opus_val32);

   channel_pos(channels, pos);

   for (c=0;c<3;c++)
      for (i=0;i<21;i++)
         maskLogE[c][i] = -QCONST16(28.f, DB_SHIFT);

   for (c=0;c<channels;c++)
   {
      int frame;
      int nb_frames = frame_size/freq_size;
      celt_assert(nb_frames*freq_size == frame_size);
      OPUS_COPY(in, mem+c*overlap, overlap);
      (*copy_channel_in)(x, 1, pcm, channels, c, len);
      celt_preemphasis(x, in+overlap, frame_size, 1, upsample, celt_mode->preemph, preemph_mem+c, 0);
#ifndef FIXED_POINT
      {
         opus_val32 sum;
         sum = celt_inner_prod(in, in, frame_size+overlap, 0);
         /* This should filter out both NaNs and ridiculous signals that could
            cause NaNs further down. */
         if (!(sum < 1e9f) || celt_isnan(sum))
         {
            OPUS_CLEAR(in, frame_size+overlap);
            preemph_mem[c] = 0;
         }
      }
#endif
      OPUS_CLEAR(bandE, 21);
      for (frame=0;frame<nb_frames;frame++)
      {
         opus_val32 tmpE[21];
         clt_mdct_forward(&celt_mode->mdct, in+960*frame, freq, celt_mode->window,
               overlap, celt_mode->maxLM-LM, 1, arch);
         if (upsample != 1)
         {
            int bound = freq_size/upsample;
            for (i=0;i<bound;i++)
               freq[i] *= upsample;
            for (;i<freq_size;i++)
               freq[i] = 0;
         }

         compute_band_energies(celt_mode, freq, tmpE, 21, 1, LM);
         /* If we have multiple frames, take the max energy. */
         for (i=0;i<21;i++)
            bandE[i] = MAX32(bandE[i], tmpE[i]);
      }
      amp2Log2(celt_mode, 21, 21, bandE, bandLogE+21*c, 1);
      /* Apply spreading function with -6 dB/band going up and -12 dB/band going down. */
      for (i=1;i<21;i++)
         bandLogE[21*c+i] = MAX16(bandLogE[21*c+i], bandLogE[21*c+i-1]-QCONST16(1.f, DB_SHIFT));
      for (i=19;i>=0;i--)
         bandLogE[21*c+i] = MAX16(bandLogE[21*c+i], bandLogE[21*c+i+1]-QCONST16(2.f, DB_SHIFT));
      if (pos[c]==1)
      {
         for (i=0;i<21;i++)
            maskLogE[0][i] = logSum(maskLogE[0][i], bandLogE[21*c+i]);
      } else if (pos[c]==3)
      {
         for (i=0;i<21;i++)
            maskLogE[2][i] = logSum(maskLogE[2][i], bandLogE[21*c+i]);
      } else if (pos[c]==2)
      {
         for (i=0;i<21;i++)
         {
            maskLogE[0][i] = logSum(maskLogE[0][i], bandLogE[21*c+i]-QCONST16(.5f, DB_SHIFT));
            maskLogE[2][i] = logSum(maskLogE[2][i], bandLogE[21*c+i]-QCONST16(.5f, DB_SHIFT));
         }
      }
#if 0
      for (i=0;i<21;i++)
         printf("%f ", bandLogE[21*c+i]);
      float sum=0;
      for (i=0;i<21;i++)
         sum += bandLogE[21*c+i];
      printf("%f ", sum/21);
#endif
      OPUS_COPY(mem+c*overlap, in+frame_size, overlap);
   }
   for (i=0;i<21;i++)
      maskLogE[1][i] = MIN32(maskLogE[0][i],maskLogE[2][i]);
   channel_offset = HALF16(celt_log2(QCONST32(2.f,14)/(channels-1)));
   for (c=0;c<3;c++)
      for (i=0;i<21;i++)
         maskLogE[c][i] += channel_offset;
#if 0
   for (c=0;c<3;c++)
   {
      for (i=0;i<21;i++)
         printf("%f ", maskLogE[c][i]);
   }
#endif
   for (c=0;c<channels;c++)
   {
      opus_val16 *mask;
      if (pos[c]!=0)
      {
         mask = &maskLogE[pos[c]-1][0];
         for (i=0;i<21;i++)
            bandLogE[21*c+i] = bandLogE[21*c+i] - mask[i];
      } else {
         for (i=0;i<21;i++)
            bandLogE[21*c+i] = 0;
      }
#if 0
      for (i=0;i<21;i++)
         printf("%f ", bandLogE[21*c+i]);
      printf("\n");
#endif
#if 0
      float sum=0;
      for (i=0;i<21;i++)
         sum += bandLogE[21*c+i];
      printf("%f ", sum/(float)QCONST32(21.f, DB_SHIFT));
      printf("\n");
#endif
   }
   RESTORE_STACK;
}

opus_int32 opus_multistream_encoder_get_size(int nb_streams, int nb_coupled_streams)
{
   int coupled_size;
   int mono_size;

   if(nb_streams<1||nb_coupled_streams>nb_streams||nb_coupled_streams<0)return 0;
   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);
   return align(sizeof(OpusMSEncoder))
        + nb_coupled_streams * align(coupled_size)
        + (nb_streams-nb_coupled_streams) * align(mono_size);
}

opus_int32 opus_multistream_surround_encoder_get_size(int channels, int mapping_family)
{
   int nb_streams;
   int nb_coupled_streams;
   opus_int32 size;

   if (mapping_family==0)
   {
      if (channels==1)
      {
         nb_streams=1;
         nb_coupled_streams=0;
      } else if (channels==2)
      {
         nb_streams=1;
         nb_coupled_streams=1;
      } else
         return 0;
   } else if (mapping_family==1 && channels<=8 && channels>=1)
   {
      nb_streams=vorbis_mappings[channels-1].nb_streams;
      nb_coupled_streams=vorbis_mappings[channels-1].nb_coupled_streams;
   } else if (mapping_family==255)
   {
      nb_streams=channels;
      nb_coupled_streams=0;
#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
   } else if (mapping_family==254)
   {
      if (!validate_ambisonics(channels, &nb_streams, &nb_coupled_streams))
         return 0;
#endif
   } else
      return 0;
   size = opus_multistream_encoder_get_size(nb_streams, nb_coupled_streams);
   if (channels>2)
   {
      size += channels*(120*sizeof(opus_val32) + sizeof(opus_val32));
   }
   return size;
}

static int opus_multistream_encoder_init_impl(
      OpusMSEncoder *st,
      opus_int32 Fs,
      int channels,
      int streams,
      int coupled_streams,
      const unsigned char *mapping,
      int application,
      MappingType mapping_type
)
{
   int coupled_size;
   int mono_size;
   int i, ret;
   char *ptr;

   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
       (streams<1) || (coupled_streams<0) || (streams>255-coupled_streams))
      return OPUS_BAD_ARG;

   st->arch = opus_select_arch();
   st->layout.nb_channels = channels;
   st->layout.nb_streams = streams;
   st->layout.nb_coupled_streams = coupled_streams;
   if (mapping_type != MAPPING_TYPE_SURROUND)
      st->lfe_stream = -1;
   st->bitrate_bps = OPUS_AUTO;
   st->application = application;
   st->variable_duration = OPUS_FRAMESIZE_ARG;
   for (i=0;i<st->layout.nb_channels;i++)
      st->layout.mapping[i] = mapping[i];
   if (!validate_layout(&st->layout))
      return OPUS_BAD_ARG;
   if (mapping_type == MAPPING_TYPE_SURROUND &&
       !validate_encoder_layout(&st->layout))
      return OPUS_BAD_ARG;
#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
   if (mapping_type == MAPPING_TYPE_AMBISONICS &&
       !validate_ambisonics(st->layout.nb_channels, NULL, NULL))
      return OPUS_BAD_ARG;
#endif
   )
      return OPUS_BAD_ARG;
   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);

   for (i=0;i<st->layout.nb_coupled_streams;i++)
   {
      ret = opus_encoder_init((OpusEncoder*)ptr, Fs, 2, application);
      if(ret!=OPUS_OK)return ret;
      if (i==st->lfe_stream)
         opus_encoder_ctl((OpusEncoder*)ptr, OPUS_SET_LFE(1));
      ptr += align(coupled_size);
   }
   for (;i<st->layout.nb_streams;i++)
   {
      ret = opus_encoder_init((OpusEncoder*)ptr, Fs, 1, application);
      if (i==st->lfe_stream)
         opus_encoder_ctl((OpusEncoder*)ptr, OPUS_SET_LFE(1));
      if(ret!=OPUS_OK)return ret;
      ptr += align(mono_size);
   }
   if (mapping_type == MAPPING_TYPE_SURROUND)
   {
      OPUS_CLEAR(ms_get_preemph_mem(st), channels);
      OPUS_CLEAR(ms_get_window_mem(st), channels*120);
   }
   st->mapping_type = mapping_type;
   return OPUS_OK;
}

int opus_multistream_encoder_init(
      OpusMSEncoder *st,
      opus_int32 Fs,
      int channels,
      int streams,
      int coupled_streams,
      const unsigned char *mapping,
      int application
)
{
   return opus_multistream_encoder_init_impl(st, Fs, channels, streams,
                                             coupled_streams, mapping,
                                             application, MAPPING_TYPE_NONE);
}

int opus_multistream_surround_encoder_init(
      OpusMSEncoder *st,
      opus_int32 Fs,
      int channels,
      int mapping_family,
      int *streams,
      int *coupled_streams,
      unsigned char *mapping,
      int application
)
{
   MappingType mapping_type;

   if ((channels>255) || (channels<1))
      return OPUS_BAD_ARG;
   st->lfe_stream = -1;
   if (mapping_family==0)
   {
      if (channels==1)
      {
         *streams=1;
         *coupled_streams=0;
         mapping[0]=0;
      } else if (channels==2)
      {
         *streams=1;
         *coupled_streams=1;
         mapping[0]=0;
         mapping[1]=1;
      } else
         return OPUS_UNIMPLEMENTED;
   } else if (mapping_family==1 && channels<=8 && channels>=1)
   {
      int i;
      *streams=vorbis_mappings[channels-1].nb_streams;
      *coupled_streams=vorbis_mappings[channels-1].nb_coupled_streams;
      for (i=0;i<channels;i++)
         mapping[i] = vorbis_mappings[channels-1].mapping[i];
      if (channels>=6)
         st->lfe_stream = *streams-1;
   } else if (mapping_family==255)
   {
      int i;
      *streams=channels;
      *coupled_streams=0;
      for(i=0;i<channels;i++)
         mapping[i] = i;
#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
   } else if (mapping_family==254)
   {
      int i;
      if (!validate_ambisonics(channels, streams, coupled_streams))
         return OPUS_BAD_ARG;
      for(i = 0; i < (*streams - *coupled_streams); i++)
         mapping[i] = i + (*coupled_streams * 2);
      for(i = 0; i < *coupled_streams * 2; i++)
         mapping[i + (*streams - *coupled_streams)] = i;
#endif
   } else
      return OPUS_UNIMPLEMENTED;

   if (channels>2 && mapping_family==1) {
      mapping_type = MAPPING_TYPE_SURROUND;
#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
   } else if (mapping_family==254)
   {
      mapping_type = MAPPING_TYPE_AMBISONICS;
#endif
   } else
   {
      mapping_type = MAPPING_TYPE_NONE;
   }
   return opus_multistream_encoder_init_impl(st, Fs, channels, *streams,
                                             *coupled_streams, mapping,
                                             application, mapping_type);
}

OpusMSEncoder *opus_multistream_encoder_create(
      opus_int32 Fs,
      int channels,
      int streams,
      int coupled_streams,
      const unsigned char *mapping,
      int application,
      int *error
)
{
   int ret;
   OpusMSEncoder *st;
   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
       (streams<1) || (coupled_streams<0) || (streams>255-coupled_streams))
   {
      if (error)
         *error = OPUS_BAD_ARG;
      return NULL;
   }
   st = (OpusMSEncoder *)opus_alloc(opus_multistream_encoder_get_size(streams, coupled_streams));
   if (st==NULL)
   {
      if (error)
         *error = OPUS_ALLOC_FAIL;
      return NULL;
   }
   ret = opus_multistream_encoder_init(st, Fs, channels, streams, coupled_streams, mapping, application);
   if (ret != OPUS_OK)
   {
      opus_free(st);
      st = NULL;
   }
   if (error)
      *error = ret;
   return st;
}

OpusMSEncoder *opus_multistream_surround_encoder_create(
      opus_int32 Fs,
      int channels,
      int mapping_family,
      int *streams,
      int *coupled_streams,
      unsigned char *mapping,
      int application,
      int *error
)
{
   int ret;
   opus_int32 size;
   OpusMSEncoder *st;
   if ((channels>255) || (channels<1))
   {
      if (error)
         *error = OPUS_BAD_ARG;
      return NULL;
   }
   size = opus_multistream_surround_encoder_get_size(channels, mapping_family);
   if (!size)
   {
      if (error)
         *error = OPUS_UNIMPLEMENTED;
      return NULL;
   }
   st = (OpusMSEncoder *)opus_alloc(size);
   if (st==NULL)
   {
      if (error)
         *error = OPUS_ALLOC_FAIL;
      return NULL;
   }
   ret = opus_multistream_surround_encoder_init(st, Fs, channels, mapping_family, streams, coupled_streams, mapping, application);
   if (ret != OPUS_OK)
   {
      opus_free(st);
      st = NULL;
   }
   if (error)
      *error = ret;
   return st;
}

static void surround_rate_allocation(
      OpusMSEncoder *st,
      opus_int32 *rate,
      int frame_size,
      opus_int32 Fs
      )
{
   int i;
   opus_int32 channel_rate;
   int stream_offset;
   int lfe_offset;
   int coupled_ratio; /* Q8 */
   int lfe_ratio;     /* Q8 */
   int nb_lfe;
   int nb_uncoupled;
   int nb_coupled;
   int nb_normal;
   opus_int32 channel_offset;
   opus_int32 bitrate;
   int total;

   nb_lfe = (st->lfe_stream!=-1);
   nb_coupled = st->layout.nb_coupled_streams;
   nb_uncoupled = st->layout.nb_streams-nb_coupled-nb_lfe;
   nb_normal = 2*nb_coupled + nb_uncoupled;

   /* Give each non-LFE channel enough bits per channel for coding band energy. */
   channel_offset = 40*IMAX(50, Fs/frame_size);

   if (st->bitrate_bps==OPUS_AUTO)
   {
      bitrate = nb_normal*(channel_offset + Fs + 10000) + 8000*nb_lfe;
   } else if (st->bitrate_bps==OPUS_BITRATE_MAX)
   {
      bitrate = nb_normal*300000 + nb_lfe*128000;
   } else {
      bitrate = st->bitrate_bps;
   }

   /* Give LFE some basic stream_channel allocation but never exceed 1/20 of the
      total rate for the non-energy part to avoid problems at really low rate. */
   lfe_offset = IMIN(bitrate/20, 3000) + 15*IMAX(50, Fs/frame_size);

   /* We give each stream (coupled or uncoupled) a starting bitrate.
      This models the main saving of coupled channels over uncoupled. */
   stream_offset = (bitrate - channel_offset*nb_normal - lfe_offset*nb_lfe)/nb_normal/2;
   stream_offset = IMAX(0, IMIN(20000, stream_offset));

   /* Coupled streams get twice the mono rate after the offset is allocated. */
   coupled_ratio = 512;
   /* Should depend on the bitrate, for now we assume LFE gets 1/8 the bits of mono */
   lfe_ratio = 32;

   total = (nb_uncoupled<<8)         /* mono */
         + coupled_ratio*nb_coupled /* stereo */
         + nb_lfe*lfe_ratio;
   channel_rate = 256*(opus_int64)(bitrate - lfe_offset*nb_lfe - stream_offset*(nb_coupled+nb_uncoupled) - channel_offset*nb_normal)/total;

   for (i=0;i<st->layout.nb_streams;i++)
   {
      if (i<st->layout.nb_coupled_streams)
         rate[i] = 2*channel_offset + IMAX(0, stream_offset+(channel_rate*coupled_ratio>>8));
      else if (i!=st->lfe_stream)
         rate[i] = channel_offset + IMAX(0, stream_offset + channel_rate);
      else
         rate[i] = IMAX(0, lfe_offset+(channel_rate*lfe_ratio>>8));
   }
}

#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
static void ambisonics_rate_allocation(
      OpusMSEncoder *st,
      opus_int32 *rate,
      int frame_size,
      opus_int32 Fs
      )
{
   int i;
   int total_rate;
   int directional_rate;
   int nondirectional_rate;
   int leftover_bits;

   /* Each nondirectional channel gets (rate_ratio_num / rate_ratio_den) times
    * as many bits as all other ambisonics channels.
    */
   const int rate_ratio_num = 4;
   const int rate_ratio_den = 3;
   const int nb_channels = st->layout.nb_streams + st->layout.nb_coupled_streams;
   const int nb_nondirectional_channels = st->layout.nb_coupled_streams * 2 + 1;
   const int nb_directional_channels = st->layout.nb_streams - 1;

   if (st->bitrate_bps==OPUS_AUTO)
   {
      total_rate = (st->layout.nb_coupled_streams + st->layout.nb_streams) *
         (Fs+60*Fs/frame_size) + st->layout.nb_streams * 15000;
   } else if (st->bitrate_bps==OPUS_BITRATE_MAX)
   {
      total_rate = nb_channels * 320000;
   } else
   {
      total_rate = st->bitrate_bps;
   }

   /* Let y be the directional rate, m be the num of nondirectional channels
    *   m = (s + 1)
    * and let p, q be integers such that the nondirectional rate is
    *   m_rate = (p / q) * y
    * Also let T be the total bitrate to allocate. Then
    *   T = (n - m) * y + m * m_rate
    * Solving for y,
    *   y = (q * T) / (m * (p - q) + n * q)
    */
   directional_rate =
      total_rate * rate_ratio_den
      / (nb_nondirectional_channels * (rate_ratio_num - rate_ratio_den)
       + nb_channels * rate_ratio_den);

   /* Calculate the nondirectional rate.
    *   m_rate = y * (p / q)
    */
   nondirectional_rate = directional_rate * rate_ratio_num / rate_ratio_den;

   /* Calculate the leftover from truncation error.
    *   leftover = T - y * (n - m) - m_rate * m
    * Place leftover bits in omnidirectional channel.
    */
   leftover_bits = total_rate
      - directional_rate * nb_directional_channels
      - nondirectional_rate * nb_nondirectional_channels;

   /* Calculate rates for each channel */
   for (i = 0; i < st->layout.nb_streams; i++)
   {
      if (i < st->layout.nb_coupled_streams)
      {
         rate[i] = nondirectional_rate * 2;
      } else if (i == st->layout.nb_coupled_streams)
      {
         rate[i] = nondirectional_rate + leftover_bits;
      } else
      {
         rate[i] = directional_rate;
      }
   }
}
#endif /* ENABLE_EXPERIMENTAL_AMBISONICS */

static opus_int32 rate_allocation(
      OpusMSEncoder *st,
      opus_int32 *rate,
      int frame_size
      )
{
   int i;
   opus_int32 rate_sum=0;
   opus_int32 Fs;
   char *ptr;

   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   opus_encoder_ctl((OpusEncoder*)ptr, OPUS_GET_SAMPLE_RATE(&Fs));

#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
   if (st->mapping_type == MAPPING_TYPE_AMBISONICS) {
     ambisonics_rate_allocation(st, rate, frame_size, Fs);
   } else
#endif
   {
     surround_rate_allocation(st, rate, frame_size, Fs);
   }

   for (i=0;i<st->layout.nb_streams;i++)
   {
      rate[i] = IMAX(rate[i], 500);
      rate_sum += rate[i];
   }
   return rate_sum;
}

/* Max size in case the encoder decides to return six frames (6 x 20 ms = 120 ms) */
#define MS_FRAME_TMP (6*1275+12)
static int opus_multistream_encode_native
(
    OpusMSEncoder *st,
    opus_copy_channel_in_func copy_channel_in,
    const void *pcm,
    int analysis_frame_size,
    unsigned char *data,
    opus_int32 max_data_bytes,
    int lsb_depth,
    downmix_func downmix,
    int float_api
)
{
   opus_int32 Fs;
   int coupled_size;
   int mono_size;
   int s;
   char *ptr;
   int tot_size;
   VARDECL(opus_val16, buf);
   VARDECL(opus_val16, bandSMR);
   unsigned char tmp_data[MS_FRAME_TMP];
   OpusRepacketizer rp;
   opus_int32 vbr;
   const CELTMode *celt_mode;
   opus_int32 bitrates[256];
   opus_val16 bandLogE[42];
   opus_val32 *mem = NULL;
   opus_val32 *preemph_mem=NULL;
   int frame_size;
   opus_int32 rate_sum;
   opus_int32 smallest_packet;
   ALLOC_STACK;

   if (st->mapping_type == MAPPING_TYPE_SURROUND)
   {
      preemph_mem = ms_get_preemph_mem(st);
      mem = ms_get_window_mem(st);
   }

   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   opus_encoder_ctl((OpusEncoder*)ptr, OPUS_GET_SAMPLE_RATE(&Fs));
   opus_encoder_ctl((OpusEncoder*)ptr, OPUS_GET_VBR(&vbr));
   opus_encoder_ctl((OpusEncoder*)ptr, CELT_GET_MODE(&celt_mode));

   frame_size = frame_size_select(analysis_frame_size, st->variable_duration, Fs);
   if (frame_size <= 0)
   {
      RESTORE_STACK;
      return OPUS_BAD_ARG;
   }

   /* Smallest packet the encoder can produce. */
   smallest_packet = st->layout.nb_streams*2-1;
   /* 100 ms needs an extra byte per stream for the ToC. */
   if (Fs/frame_size == 10)
     smallest_packet += st->layout.nb_streams;
   if (max_data_bytes < smallest_packet)
   {
      RESTORE_STACK;
      return OPUS_BUFFER_TOO_SMALL;
   }
   ALLOC(buf, 2*frame_size, opus_val16);
   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);

   ALLOC(bandSMR, 21*st->layout.nb_channels, opus_val16);
   if (st->mapping_type == MAPPING_TYPE_SURROUND)
   {
      surround_analysis(celt_mode, pcm, bandSMR, mem, preemph_mem, frame_size, 120, st->layout.nb_channels, Fs, copy_channel_in, st->arch);
   }

   /* Compute bitrate allocation between streams (this could be a lot better) */
   rate_sum = rate_allocation(st, bitrates, frame_size);

   if (!vbr)
   {
      if (st->bitrate_bps == OPUS_AUTO)
      {
         max_data_bytes = IMIN(max_data_bytes, 3*rate_sum/(3*8*Fs/frame_size));
      } else if (st->bitrate_bps != OPUS_BITRATE_MAX)
      {
         max_data_bytes = IMIN(max_data_bytes, IMAX(smallest_packet,
                          3*st->bitrate_bps/(3*8*Fs/frame_size)));
      }
   }
   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   for (s=0;s<st->layout.nb_streams;s++)
   {
      OpusEncoder *enc;
      enc = (OpusEncoder*)ptr;
      if (s < st->layout.nb_coupled_streams)
         ptr += align(coupled_size);
      else
         ptr += align(mono_size);
      opus_encoder_ctl(enc, OPUS_SET_BITRATE(bitrates[s]));
      if (st->mapping_type == MAPPING_TYPE_SURROUND)
      {
         opus_int32 equiv_rate;
         equiv_rate = st->bitrate_bps;
         if (frame_size*50 < Fs)
            equiv_rate -= 60*(Fs/frame_size - 50)*st->layout.nb_channels;
         if (equiv_rate > 10000*st->layout.nb_channels)
            opus_encoder_ctl(enc, OPUS_SET_BANDWIDTH(OPUS_BANDWIDTH_FULLBAND));
         else if (equiv_rate > 7000*st->layout.nb_channels)
            opus_encoder_ctl(enc, OPUS_SET_BANDWIDTH(OPUS_BANDWIDTH_SUPERWIDEBAND));
         else if (equiv_rate > 5000*st->layout.nb_channels)
            opus_encoder_ctl(enc, OPUS_SET_BANDWIDTH(OPUS_BANDWIDTH_WIDEBAND));
         else
            opus_encoder_ctl(enc, OPUS_SET_BANDWIDTH(OPUS_BANDWIDTH_NARROWBAND));
         if (s < st->layout.nb_coupled_streams)
         {
            /* To preserve the spatial image, force stereo CELT on coupled streams */
            opus_encoder_ctl(enc, OPUS_SET_FORCE_MODE(MODE_CELT_ONLY));
            opus_encoder_ctl(enc, OPUS_SET_FORCE_CHANNELS(2));
         }
      }
#ifdef ENABLE_EXPERIMENTAL_AMBISONICS
      else if (st->mapping_type == MAPPING_TYPE_AMBISONICS) {
        opus_encoder_ctl(enc, OPUS_SET_FORCE_MODE(MODE_CELT_ONLY));
      }
#endif
   }

   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   /* Counting ToC */
   tot_size = 0;
   for (s=0;s<st->layout.nb_streams;s++)
   {
      OpusEncoder *enc;
      int len;
      int curr_max;
      int c1, c2;
      int ret;

      opus_repacketizer_init(&rp);
      enc = (OpusEncoder*)ptr;
      if (s < st->layout.nb_coupled_streams)
      {
         int i;
         int left, right;
         left = get_left_channel(&st->layout, s, -1);
         right = get_right_channel(&st->layout, s, -1);
         (*copy_channel_in)(buf, 2,
            pcm, st->layout.nb_channels, left, frame_size);
         (*copy_channel_in)(buf+1, 2,
            pcm, st->layout.nb_channels, right, frame_size);
         ptr += align(coupled_size);
         if (st->mapping_type == MAPPING_TYPE_SURROUND)
         {
            for (i=0;i<21;i++)
            {
               bandLogE[i] = bandSMR[21*left+i];
               bandLogE[21+i] = bandSMR[21*right+i];
            }
         }
         c1 = left;
         c2 = right;
      } else {
         int i;
         int chan = get_mono_channel(&st->layout, s, -1);
         (*copy_channel_in)(buf, 1,
            pcm, st->layout.nb_channels, chan, frame_size);
         ptr += align(mono_size);
         if (st->mapping_type == MAPPING_TYPE_SURROUND)
         {
            for (i=0;i<21;i++)
               bandLogE[i] = bandSMR[21*chan+i];
         }
         c1 = chan;
         c2 = -1;
      }
      if (st->mapping_type == MAPPING_TYPE_SURROUND)
         opus_encoder_ctl(enc, OPUS_SET_ENERGY_MASK(bandLogE));
      /* number of bytes left (+Toc) */
      curr_max = max_data_bytes - tot_size;
      /* Reserve one byte for the last stream and two for the others */
      curr_max -= IMAX(0,2*(st->layout.nb_streams-s-1)-1);
      /* For 100 ms, reserve an extra byte per stream for the ToC */
      if (Fs/frame_size == 10)
        curr_max -= st->layout.nb_streams-s-1;
      curr_max = IMIN(curr_max,MS_FRAME_TMP);
      /* Repacketizer will add one or two bytes for self-delimited frames */
      if (s != st->layout.nb_streams-1) curr_max -=  curr_max>253 ? 2 : 1;
      if (!vbr && s == st->layout.nb_streams-1)
         opus_encoder_ctl(enc, OPUS_SET_BITRATE(curr_max*(8*Fs/frame_size)));
      len = opus_encode_native(enc, buf, frame_size, tmp_data, curr_max, lsb_depth,
            pcm, analysis_frame_size, c1, c2, st->layout.nb_channels, downmix, float_api);
      if (len<0)
      {
         RESTORE_STACK;
         return len;
      }
      /* We need to use the repacketizer to add the self-delimiting lengths
         while taking into account the fact that the encoder can now return
         more than one frame at a time (e.g. 60 ms CELT-only) */
      ret = opus_repacketizer_cat(&rp, tmp_data, len);
      /* If the opus_repacketizer_cat() fails, then something's seriously wrong
         with the encoder. */
      if (ret != OPUS_OK)
      {
         RESTORE_STACK;
         return OPUS_INTERNAL_ERROR;
      }
      len = opus_repacketizer_out_range_impl(&rp, 0, opus_repacketizer_get_nb_frames(&rp),
            data, max_data_bytes-tot_size, s != st->layout.nb_streams-1, !vbr && s == st->layout.nb_streams-1);
      data += len;
      tot_size += len;
   }
   /*printf("\n");*/
   RESTORE_STACK;
   return tot_size;
}

#if !defined(DISABLE_FLOAT_API)
static void opus_copy_channel_in_float(
  opus_val16 *dst,
  int dst_stride,
  const void *src,
  int src_stride,
  int src_channel,
  int frame_size
)
{
   const float *float_src;
   opus_int32 i;
   float_src = (const float *)src;
   for (i=0;i<frame_size;i++)
#if defined(FIXED_POINT)
      dst[i*dst_stride] = FLOAT2INT16(float_src[i*src_stride+src_channel]);
#else
      dst[i*dst_stride] = float_src[i*src_stride+src_channel];
#endif
}
#endif

static void opus_copy_channel_in_short(
  opus_val16 *dst,
  int dst_stride,
  const void *src,
  int src_stride,
  int src_channel,
  int frame_size
)
{
   const opus_int16 *short_src;
   opus_int32 i;
   short_src = (const opus_int16 *)src;
   for (i=0;i<frame_size;i++)
#if defined(FIXED_POINT)
      dst[i*dst_stride] = short_src[i*src_stride+src_channel];
#else
      dst[i*dst_stride] = (1/32768.f)*short_src[i*src_stride+src_channel];
#endif
}


#ifdef FIXED_POINT
int opus_multistream_encode(
    OpusMSEncoder *st,
    const opus_val16 *pcm,
    int frame_size,
    unsigned char *data,
    opus_int32 max_data_bytes
)
{
   return opus_multistream_encode_native(st, opus_copy_channel_in_short,
      pcm, frame_size, data, max_data_bytes, 16, downmix_int, 0);
}

#ifndef DISABLE_FLOAT_API
int opus_multistream_encode_float(
    OpusMSEncoder *st,
    const float *pcm,
    int frame_size,
    unsigned char *data,
    opus_int32 max_data_bytes
)
{
   return opus_multistream_encode_native(st, opus_copy_channel_in_float,
      pcm, frame_size, data, max_data_bytes, 16, downmix_float, 1);
}
#endif

#else

int opus_multistream_encode_float
(
    OpusMSEncoder *st,
    const opus_val16 *pcm,
    int frame_size,
    unsigned char *data,
    opus_int32 max_data_bytes
)
{
   return opus_multistream_encode_native(st, opus_copy_channel_in_float,
      pcm, frame_size, data, max_data_bytes, 24, downmix_float, 1);
}

int opus_multistream_encode(
    OpusMSEncoder *st,
    const opus_int16 *pcm,
    int frame_size,
    unsigned char *data,
    opus_int32 max_data_bytes
)
{
   return opus_multistream_encode_native(st, opus_copy_channel_in_short,
      pcm, frame_size, data, max_data_bytes, 16, downmix_int, 0);
}
#endif

int opus_multistream_encoder_ctl(OpusMSEncoder *st, int request, ...)
{
   va_list ap;
   int coupled_size, mono_size;
   char *ptr;
   int ret = OPUS_OK;

   va_start(ap, request);

   coupled_size = opus_encoder_get_size(2);
   mono_size = opus_encoder_get_size(1);
   ptr = (char*)st + align(sizeof(OpusMSEncoder));
   switch (request)
   {
   case OPUS_SET_BITRATE_REQUEST:
   {
      opus_int32 value = va_arg(ap, opus_int32);
      if (value != OPUS_AUTO && value != OPUS_BITRATE_MAX)
      {
         if (value <= 0)
            goto bad_arg;
         value = IMIN(300000*st->layout.nb_channels, IMAX(500*st->layout.nb_channels, value));
      }
      st->bitrate_bps = value;
   }
   break;
   case OPUS_GET_BITRATE_REQUEST:
   {
      int s;
      opus_int32 *value = va_arg(ap, opus_int32*);
      if (!value)
      {
         goto bad_arg;
      }
      *value = 0;
      for (s=0;s<st->layout.nb_streams;s++)
      {
         opus_int32 rate;
         OpusEncoder *enc;
         enc = (OpusEncoder*)ptr;
         if (s < st->layout.nb_coupled_streams)
            ptr += align(coupled_size);
         else
            ptr += align(mono_size);
         opus_encoder_ctl(enc, request, &rate);
         *value += rate;
      }
   }
   break;
   case OPUS_GET_LSB_DEPTH_REQUEST:
   case OPUS_GET_VBR_REQUEST:
   case OPUS_GET_APPLICATION_REQUEST:
   case OPUS_GET_BANDWIDTH_REQUEST:
   case OPUS_GET_COMPLEXITY_REQUEST:
   case OPUS_GET_PACKET_LOSS_PERC_REQUEST:
   case OPUS_GET_DTX_REQUEST:
   case OPUS_GET_VOICE_RATIO_REQUEST:
   case OPUS_GET_VBR_CONSTRAINT_REQUEST:
   case OPUS_GET_SIGNAL_REQUEST:
   case OPUS_GET_LOOKAHEAD_REQUEST:
   case OPUS_GET_SAMPLE_RATE_REQUEST:
   case OPUS_GET_INBAND_FEC_REQUEST:
   case OPUS_GET_FORCE_CHANNELS_REQUEST:
   case OPUS_GET_PREDICTION_DISABLED_REQUEST:
   case OPUS_GET_PHASE_INVERSION_DISABLED_REQUEST:
   {
      OpusEncoder *enc;
      /* For int32* GET params, just query the first stream */
      opus_int32 *value = va_arg(ap, opus_int32*);
      enc = (OpusEncoder*)ptr;
      ret = opus_encoder_ctl(enc, request, value);
   }
   break;
   case OPUS_GET_FINAL_RANGE_REQUEST:
   {
      int s;
      opus_uint32 *value = va_arg(ap, opus_uint32*);
      opus_uint32 tmp;
      if (!value)
      {
         goto bad_arg;
      }
      *value=0;
      for (s=0;s<st->layout.nb_streams;s++)
      {
         OpusEncoder *enc;
         enc = (OpusEncoder*)ptr;
         if (s < st->layout.nb_coupled_streams)
            ptr += align(coupled_size);
         else
            ptr += align(mono_size);
         ret = opus_encoder_ctl(enc, request, &tmp);
         if (ret != OPUS_OK) break;
         *value ^= tmp;
      }
   }
   break;
   case OPUS_SET_LSB_DEPTH_REQUEST:
   case OPUS_SET_COMPLEXITY_REQUEST:
   case OPUS_SET_VBR_REQUEST:
   case OPUS_SET_VBR_CONSTRAINT_REQUEST:
   case OPUS_SET_MAX_BANDWIDTH_REQUEST:
   case OPUS_SET_BANDWIDTH_REQUEST:
   case OPUS_SET_SIGNAL_REQUEST:
   case OPUS_SET_APPLICATION_REQUEST:
   case OPUS_SET_INBAND_FEC_REQUEST:
   case OPUS_SET_PACKET_LOSS_PERC_REQUEST:
   case OPUS_SET_DTX_REQUEST:
   case OPUS_SET_FORCE_MODE_REQUEST:
   case OPUS_SET_FORCE_CHANNELS_REQUEST:
   case OPUS_SET_PREDICTION_DISABLED_REQUEST:
   case OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST:
   {
      int s;
      /* This works for int32 params */
      opus_int32 value = va_arg(ap, opus_int32);
      for (s=0;s<st->layout.nb_streams;s++)
      {
         OpusEncoder *enc;

         enc = (OpusEncoder*)ptr;
         if (s < st->layout.nb_coupled_streams)
            ptr += align(coupled_size);
         else
            ptr += align(mono_size);
         ret = opus_encoder_ctl(enc, request, value);
         if (ret != OPUS_OK)
            break;
      }
   }
   break;
   case OPUS_MULTISTREAM_GET_ENCODER_STATE_REQUEST:
   {
      int s;
      opus_int32 stream_id;
      OpusEncoder **value;
      stream_id = va_arg(ap, opus_int32);
      if (stream_id<0 || stream_id >= st->layout.nb_streams)
         ret = OPUS_BAD_ARG;
      value = va_arg(ap, OpusEncoder**);
      if (!value)
      {
         goto bad_arg;
      }
      for (s=0;s<stream_id;s++)
      {
         if (s < st->layout.nb_coupled_streams)
            ptr += align(coupled_size);
         else
            ptr += align(mono_size);
      }
      *value = (OpusEncoder*)ptr;
   }
   break;
   case OPUS_SET_EXPERT_FRAME_DURATION_REQUEST:
   {
       opus_int32 value = va_arg(ap, opus_int32);
       st->variable_duration = value;
   }
   break;
   case OPUS_GET_EXPERT_FRAME_DURATION_REQUEST:
   {
       opus_int32 *value = va_arg(ap, opus_int32*);
       if (!value)
       {
          goto bad_arg;
       }
       *value = st->variable_duration;
   }
   break;
   case OPUS_RESET_STATE:
   {
      int s;
      if (st->mapping_type == MAPPING_TYPE_SURROUND)
      {
         OPUS_CLEAR(ms_get_preemph_mem(st), st->layout.nb_channels);
         OPUS_CLEAR(ms_get_window_mem(st), st->layout.nb_channels*120);
      }
      for (s=0;s<st->layout.nb_streams;s++)
      {
         OpusEncoder *enc;
         enc = (OpusEncoder*)ptr;
         if (s < st->layout.nb_coupled_streams)
            ptr += align(coupled_size);
         else
            ptr += align(mono_size);
         ret = opus_encoder_ctl(enc, OPUS_RESET_STATE);
         if (ret != OPUS_OK)
            break;
      }
   }
   break;
   default:
      ret = OPUS_UNIMPLEMENTED;
      break;
   }

   va_end(ap);
   return ret;
bad_arg:
   va_end(ap);
   return OPUS_BAD_ARG;
}

void opus_multistream_encoder_destroy(OpusMSEncoder *st)
{
    opus_free(st);
}