/* 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 */

};

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;

}

static int validate_ambisonics(int nb_channels, int *nb_streams, int *nb_coupled_streams)

{

   int order_plus_one;

   int acn_channels;

   int nondiegetic_channels;

   if (nb_channels < 1 || nb_channels > 227)

      return 0;

   order_plus_one = isqrt32(nb_channels);

   acn_channels = order_plus_one * order_plus_one;

   nondiegetic_channels = nb_channels - acn_channels;

   if (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;

}

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, NULL);

      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 < 1e18f) || 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, arch);

         /* 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;

   } else if (mapping_family==2)

   {

      if (!validate_ambisonics(channels, &nb_streams, &nb_coupled_streams))

         return 0;

   } 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;

   if (mapping_type == MAPPING_TYPE_AMBISONICS &&

       !validate_ambisonics(st->layout.nb_channels, NULL, NULL))

      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;

   } else if (mapping_family==2)

   {

      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;

   } else

      return OPUS_UNIMPLEMENTED;

   if (channels>2 && mapping_family==1) {

      mapping_type = MAPPING_TYPE_SURROUND;

   } else if (mapping_family==2)

   {

      mapping_type = MAPPING_TYPE_AMBISONICS;

   } 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));

   }

}

static void ambisonics_rate_allocation(

      OpusMSEncoder *st,

      opus_int32 *rate,

      int frame_size,

      opus_int32 Fs

      )

{

   int i;

   opus_int32 total_rate;

   opus_int32 per_stream_rate;

   const int nb_channels = st->layout.nb_streams + st->layout.nb_coupled_streams;

   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 * (opus_int32)15000;

   } else if (st->bitrate_bps==OPUS_BITRATE_MAX)

   {

      total_rate = nb_channels * 320000;

   } else

   {

      total_rate = st->bitrate_bps;

   }

   /* Allocate equal number of bits to Ambisonic (uncoupled) and non-diegetic

    * (coupled) streams */

   per_stream_rate = total_rate / st->layout.nb_streams;

   for (i = 0; i < st->layout.nb_streams; i++)

   {

     rate[i] = per_stream_rate;

   }

}

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));

   if (st->mapping_type == MAPPING_TYPE_AMBISONICS) {

     ambisonics_rate_allocation(st, rate, frame_size, Fs);

   } else

   {

     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)

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,

    void *user_data

)

{

   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;