1 files changed, 323 insertions, 239 deletions

diff --git a/src/opus_multistream_encoder.c b/src/opus_multistream_encoder.c
index 4cddbffd..31447bf9 100644
--- a/src/opus_multistream_encoder.c
+++ b/src/opus_multistream_encoder.c
@@ -36,8 +36,11 @@
 #include <stdarg.h>
 #include "float_cast.h"
 #include "os_support.h"
-#include "analysis.h"
 #include "mathops.h"
+#include "mdct.h"
+#include "modes.h"
+#include "bands.h"
+#include "quant_bands.h"
 
 typedef struct {
    int nb_streams;
@@ -57,17 +60,65 @@ static const VorbisLayout vorbis_mappings[8] = {
       {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
+);
+
 struct OpusMSEncoder {
-   TonalityAnalysisState analysis;
    ChannelLayout layout;
    int lfe_stream;
+   int application;
    int variable_duration;
    int surround;
    opus_int32 bitrate_bps;
    opus_val32 subframe_mem[3];
    /* 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);
+   }
+   return (opus_val32*)(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);
+   }
+   return (opus_val32*)ptr;
+}
 
 static int validate_encoder_layout(const ChannelLayout *layout)
 {
@@ -88,6 +139,206 @@ static int validate_encoder_layout(const ChannelLayout *layout)
    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))
+      return max;
+#ifdef FIXED_POINT
+   low = SHR32(diff, DB_SHIFT-1);
+   frac = SHL16(diff - SHL16(low, DB_SHIFT-1), 16-DB_SHIFT);
+#else
+   low = 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 c;
+   int i;
+   int LM;
+   int pos[8] = {0};
+   int upsample;
+   int frame_size;
+   opus_val32 bandE[21];
+   opus_val16 maskLogE[3][21];
+   VARDECL(opus_val32, in);
+   VARDECL(opus_val16, x);
+   VARDECL(opus_val32, out);
+   SAVE_STACK;
+
+   upsample = resampling_factor(rate);
+   frame_size = len*upsample;
+
+   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, frame_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++)
+   {
+      OPUS_COPY(in, mem+c*overlap, overlap);
+      (*copy_channel_in)(x, 1, pcm, channels, c, len);
+      preemphasis(x, in+overlap, frame_size, 1, upsample, celt_mode->preemph, preemph_mem+c, 0);
+      clt_mdct_forward(&celt_mode->mdct, in, freq, celt_mode->window, overlap, celt_mode->maxLM-LM, 1);
+      if (upsample != 1)
+      {
+         int bound = len;
+         for (i=0;i<bound;i++)
+            freq[i] *= upsample;
+         for (;i<frame_size;i++)
+            freq[i] = 0;
+      }
+
+      compute_band_energies(celt_mode, freq, bandE, 21, 1, 1<<LM);
+      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]);
+//#else
+      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]);
+   for (c=0;c<3;c++)
+      for (i=0;i<21;i++)
+         maskLogE[c][i] += QCONST16(.5f, DB_SHIFT)*log2(2.f/(channels-1));
+#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/21);
+      printf("\n");
+#endif
+   }
+   RESTORE_STACK;
+}
 
 opus_int32 opus_multistream_encoder_get_size(int nb_streams, int nb_coupled_streams)
 {
@@ -132,7 +383,9 @@ opus_int32 opus_multistream_surround_encoder_get_size(int channels, int mapping_
       return 0;
    size = opus_multistream_encoder_get_size(nb_streams, nb_coupled_streams);
    if (channels>2)
-      size += align(opus_encoder_get_size(2));
+   {
+      size += channels*(120*sizeof(opus_val32) + sizeof(opus_val32));
+   }
    return size;
 }
 
@@ -161,10 +414,10 @@ static int opus_multistream_encoder_init_impl(
    st->layout.nb_streams = streams;
    st->layout.nb_coupled_streams = coupled_streams;
    st->subframe_mem[0]=st->subframe_mem[1]=st->subframe_mem[2]=0;
-   OPUS_CLEAR(&st->analysis,1);
    if (!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];
@@ -192,10 +445,8 @@ static int opus_multistream_encoder_init_impl(
    }
    if (surround)
    {
-      OpusEncoder *downmix_enc;
-      downmix_enc = (OpusEncoder*)ptr;
-      ret = opus_encoder_init(downmix_enc, Fs, 2, OPUS_APPLICATION_AUDIO);
-      if(ret!=OPUS_OK)return ret;
+      OPUS_CLEAR(ms_get_preemph_mem(st), channels);
+      OPUS_CLEAR(ms_get_window_mem(st), channels*120);
    }
    st->surround = surround;
    return OPUS_OK;
@@ -339,22 +590,6 @@ OpusMSEncoder *opus_multistream_surround_encoder_create(
    return st;
 }
 
-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 void (*opus_surround_downmix_funct)(
-  opus_val16 *dst,
-  const void *src,
-  int channels,
-  int frame_size
-);
-
 static void surround_rate_allocation(
       OpusMSEncoder *st,
       opus_int32 *rate,
@@ -433,15 +668,11 @@ static int opus_multistream_encode_native
     OpusMSEncoder *st,
     opus_copy_channel_in_func copy_channel_in,
     const void *pcm,
-    int frame_size,
+    int analysis_frame_size,
     unsigned char *data,
     opus_int32 max_data_bytes,
     int lsb_depth,
-    opus_surround_downmix_funct surround_downmix
-#ifndef FIXED_POINT
-    , downmix_func downmix
-    , const void *pcm_analysis
-#endif
+    downmix_func downmix
 )
 {
    opus_int32 Fs;
@@ -451,31 +682,29 @@ static int opus_multistream_encode_native
    char *ptr;
    int tot_size;
    VARDECL(opus_val16, buf);
+   VARDECL(opus_val16, bandSMR);
    unsigned char tmp_data[MS_FRAME_TMP];
    OpusRepacketizer rp;
    opus_int32 complexity;
-#ifndef FIXED_POINT
-   AnalysisInfo analysis_info;
-#endif
    const CELTMode *celt_mode;
    opus_int32 bitrates[256];
    opus_val16 bandLogE[42];
-   opus_val16 bandLogE_mono[21];
+   opus_val32 *mem = NULL;
+   opus_val32 *preemph_mem=NULL;
+   int frame_size;
    ALLOC_STACK;
 
+   if (st->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_COMPLEXITY(&complexity));
    opus_encoder_ctl((OpusEncoder*)ptr, CELT_GET_MODE(&celt_mode));
 
-   if (400*frame_size < Fs)
-   {
-      RESTORE_STACK;
-      return OPUS_BAD_ARG;
-   }
-#ifndef FIXED_POINT
-   analysis_info.valid = 0;
-   if (complexity >= 7 && Fs==48000)
    {
       opus_int32 delay_compensation;
       int channels;
@@ -483,13 +712,15 @@ static int opus_multistream_encode_native
       channels = st->layout.nb_streams + st->layout.nb_coupled_streams;
       opus_encoder_ctl((OpusEncoder*)ptr, OPUS_GET_LOOKAHEAD(&delay_compensation));
       delay_compensation -= Fs/400;
+      frame_size = compute_frame_size(pcm, analysis_frame_size,
+            st->variable_duration, channels, Fs, st->bitrate_bps,
+            delay_compensation, downmix, st->subframe_mem);
+   }
 
-      frame_size = run_analysis(&st->analysis, celt_mode, pcm, pcm_analysis,
-            frame_size, st->variable_duration, channels, Fs, st->bitrate_bps, delay_compensation, lsb_depth, downmix, &analysis_info);
-   } else
-#endif
+   if (400*frame_size < Fs)
    {
-      frame_size = frame_size_select(frame_size, st->variable_duration, Fs);
+      RESTORE_STACK;
+      return OPUS_BAD_ARG;
    }
    /* Validate frame_size before using it to allocate stack space.
       This mirrors the checks in opus_encode[_float](). */
@@ -504,42 +735,10 @@ static int opus_multistream_encode_native
    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->surround)
    {
-      int i;
-      unsigned char dummy[512];
-      /* Temporary kludge -- remove */
-      OpusEncoder *downmix_enc;
-
-      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);
-      }
-      downmix_enc = (OpusEncoder*)ptr;
-      surround_downmix(buf, pcm, st->layout.nb_channels, frame_size);
-      opus_encoder_ctl(downmix_enc, OPUS_SET_ENERGY_SAVE(bandLogE));
-      opus_encoder_ctl(downmix_enc, OPUS_SET_BANDWIDTH(OPUS_BANDWIDTH_FULLBAND));
-      opus_encoder_ctl(downmix_enc, OPUS_SET_FORCE_MODE(MODE_CELT_ONLY));
-      opus_encoder_ctl(downmix_enc, OPUS_SET_FORCE_CHANNELS(2));
-      opus_encode_native(downmix_enc, buf, frame_size, dummy, 512, lsb_depth
-#ifndef FIXED_POINT
-            , &analysis_info
-#endif
-            );
-      /* Combines the left and right mask into a centre mask. We
-         use an approximation for the log of the sum of the energies. */
-      for(i=0;i<21;i++)
-      {
-         opus_val16 diff;
-         diff = ABS16(SUB16(bandLogE[i], bandLogE[21+i]));
-         diff = diff + HALF16(diff);
-         diff = SHR32(HALF32(celt_exp2(-diff)), 16-DB_SHIFT);
-         bandLogE_mono[i] = MAX16(bandLogE[i], bandLogE[21+i]) + diff;
-      }
+      surround_analysis(celt_mode, pcm, bandSMR, mem, preemph_mem, frame_size, 120, st->layout.nb_channels, Fs, copy_channel_in);
    }
 
    if (max_data_bytes < 4*st->layout.nb_streams-1)
@@ -563,10 +762,24 @@ static int opus_multistream_encode_native
       opus_encoder_ctl(enc, OPUS_SET_BITRATE(bitrates[s]));
       if (st->surround)
       {
-         opus_encoder_ctl(enc, OPUS_SET_FORCE_MODE(MODE_CELT_ONLY));
-         opus_encoder_ctl(enc, OPUS_SET_BANDWIDTH(OPUS_BANDWIDTH_FULLBAND));
+         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 > 112000)
+            opus_encoder_ctl(enc, OPUS_SET_BANDWIDTH(OPUS_BANDWIDTH_FULLBAND));
+         else if (equiv_rate > 76000)
+            opus_encoder_ctl(enc, OPUS_SET_BANDWIDTH(OPUS_BANDWIDTH_SUPERWIDEBAND));
+         else if (equiv_rate > 48000)
+            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));
+         }
       }
    }
 
@@ -578,11 +791,13 @@ static int opus_multistream_encode_native
       OpusEncoder *enc;
       int len;
       int curr_max;
+      int c1, c2;
 
       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);
@@ -591,28 +806,39 @@ static int opus_multistream_encode_native
          (*copy_channel_in)(buf+1, 2,
             pcm, st->layout.nb_channels, right, frame_size);
          ptr += align(coupled_size);
-         /* FIXME: This isn't correct for the coupled center channels in
-            6.1 surround configuration */
          if (st->surround)
-            opus_encoder_ctl(enc, OPUS_SET_ENERGY_MASK(bandLogE));
+         {
+            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->surround)
-            opus_encoder_ctl(enc, OPUS_SET_ENERGY_MASK(bandLogE_mono));
+         {
+            for (i=0;i<21;i++)
+               bandLogE[i] = bandSMR[21*chan+i];
+         }
+         c1 = chan;
+         c2 = -1;
       }
+      if (st->surround)
+         opus_encoder_ctl(enc, OPUS_SET_ENERGY_MASK(bandLogE));
       /* number of bytes left (+Toc) */
       curr_max = max_data_bytes - tot_size;
       /* Reserve three bytes for the last stream and four for the others */
       curr_max -= IMAX(0,4*(st->layout.nb_streams-s-1)-1);
       curr_max = IMIN(curr_max,MS_FRAME_TMP);
-      len = opus_encode_native(enc, buf, frame_size, tmp_data, curr_max, lsb_depth
-#ifndef FIXED_POINT
-            , &analysis_info
-#endif
-            );
+      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);
       if (len<0)
       {
          RESTORE_STACK;
@@ -626,50 +852,12 @@ static int opus_multistream_encode_native
       data += len;
       tot_size += len;
    }
+   /*printf("\n");*/
    RESTORE_STACK;
    return tot_size;
 
 }
 
-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 !defined(DISABLE_FLOAT_API)
 static void opus_copy_channel_in_float(
   opus_val16 *dst,
@@ -690,57 +878,6 @@ static void opus_copy_channel_in_float(
       dst[i*dst_stride] = float_src[i*src_stride+src_channel];
 #endif
 }
-
-static void opus_surround_downmix_float(
-  opus_val16 *dst,
-  const void *src,
-  int channels,
-  int frame_size
-)
-{
-   const float *float_src;
-   opus_int32 i;
-   int pos[8] = {0};
-   int c;
-   float_src = (const float *)src;
-
-   channel_pos(channels, pos);
-   for (i=0;i<2*frame_size;i++)
-      dst[i]=0;
-
-   for (c=0;c<channels;c++)
-   {
-      if (pos[c]==1)
-      {
-         for (i=0;i<frame_size;i++)
-#if defined(FIXED_POINT)
-            dst[2*i] += SHR16(FLOAT2INT16(float_src[i*channels+c]),3);
-#else
-            dst[2*i] += float_src[i*channels+c];
-#endif
-      } else if (pos[c]==3)
-      {
-         for (i=0;i<frame_size;i++)
-#if defined(FIXED_POINT)
-            dst[2*i+1] += SHR16(FLOAT2INT16(float_src[i*channels+c]),3);
-#else
-            dst[2*i+1] += float_src[i*channels+c];
-#endif
-      } else if (pos[c]==2)
-      {
-         for (i=0;i<frame_size;i++)
-         {
-#if defined(FIXED_POINT)
-            dst[2*i] += SHR32(MULT16_16(QCONST16(.70711f,15), FLOAT2INT16(float_src[i*channels+c])),3+15);
-            dst[2*i+1] += SHR32(MULT16_16(QCONST16(.70711f,15), FLOAT2INT16(float_src[i*channels+c])),3+15);
-#else
-            dst[2*i] += .707f*float_src[i*channels+c];
-            dst[2*i+1] += .707f*float_src[i*channels+c];
-#endif
-         }
-      }
-   }
-}
 #endif
 
 static void opus_copy_channel_in_short(
@@ -763,57 +900,6 @@ static void opus_copy_channel_in_short(
 #endif
 }
 
-static void opus_surround_downmix_short(
-  opus_val16 *dst,
-  const void *src,
-  int channels,
-  int frame_size
-)
-{
-   const opus_int16 *short_src;
-   opus_int32 i;
-   int pos[8] = {0};
-   int c;
-   short_src = (const opus_int16 *)src;
-
-   channel_pos(channels, pos);
-   for (i=0;i<2*frame_size;i++)
-      dst[i]=0;
-
-   for (c=0;c<channels;c++)
-   {
-      if (pos[c]==1)
-      {
-         for (i=0;i<frame_size;i++)
-#if defined(FIXED_POINT)
-            dst[2*i] += SHR16(short_src[i*channels+c],3);
-#else
-            dst[2*i] += (1/32768.f)*short_src[i*channels+c];
-#endif
-      } else if (pos[c]==3)
-      {
-         for (i=0;i<frame_size;i++)
-#if defined(FIXED_POINT)
-            dst[2*i+1] += SHR16(short_src[i*channels+c],3);
-#else
-            dst[2*i+1] += (1/32768.f)*short_src[i*channels+c];
-#endif
-      } else if (pos[c]==2)
-      {
-         for (i=0;i<frame_size;i++)
-         {
-#if defined(FIXED_POINT)
-            dst[2*i] += SHR32(MULT16_16(QCONST16(.70711f,15), short_src[i*channels+c]),3+15);
-            dst[2*i+1] += SHR32(MULT16_16(QCONST16(.70711f,15), short_src[i*channels+c]),3+15);
-#else
-            dst[2*i] += (.707f/32768.f)*short_src[i*channels+c];
-            dst[2*i+1] += (.707f/32768.f)*short_src[i*channels+c];
-#endif
-         }
-      }
-   }
-}
-
 
 #ifdef FIXED_POINT
 int opus_multistream_encode(
@@ -825,7 +911,7 @@ int opus_multistream_encode(
 )
 {
    return opus_multistream_encode_native(st, opus_copy_channel_in_short,
-      pcm, frame_size, data, max_data_bytes, 16, opus_surround_downmix_short);
+      pcm, frame_size, data, max_data_bytes, 16, downmix_int);
 }
 
 #ifndef DISABLE_FLOAT_API
@@ -838,7 +924,7 @@ int opus_multistream_encode_float(
 )
 {
    return opus_multistream_encode_native(st, opus_copy_channel_in_float,
-      pcm, frame_size, data, max_data_bytes, 16, opus_surround_downmix_float);
+      pcm, frame_size, data, max_data_bytes, 16, downmix_float);
 }
 #endif
 
@@ -853,9 +939,8 @@ int opus_multistream_encode_float
     opus_int32 max_data_bytes
 )
 {
-   int channels = st->layout.nb_streams + st->layout.nb_coupled_streams;
    return opus_multistream_encode_native(st, opus_copy_channel_in_float,
-      pcm, frame_size, data, max_data_bytes, 24, opus_surround_downmix_float, downmix_float, pcm+channels*st->analysis.analysis_offset);
+      pcm, frame_size, data, max_data_bytes, 24, downmix_float);
 }
 
 int opus_multistream_encode(
@@ -866,9 +951,8 @@ int opus_multistream_encode(
     opus_int32 max_data_bytes
 )
 {
-   int channels = st->layout.nb_streams + st->layout.nb_coupled_streams;
    return opus_multistream_encode_native(st, opus_copy_channel_in_short,
-      pcm, frame_size, data, max_data_bytes, 16, opus_surround_downmix_short, downmix_int, pcm+channels*st->analysis.analysis_offset);
+      pcm, frame_size, data, max_data_bytes, 16, downmix_int);
 }
 #endif