Splits out the Opus multi-stream encoder and decoder

5 files changed, 1030 insertions, 939 deletions

diff --git a/opus_sources.mk b/opus_sources.mk
index 81eaef06..e4eeb919 100644
--- a/opus_sources.mk
+++ b/opus_sources.mk
@@ -2,6 +2,8 @@ OPUS_SOURCES = src/opus.c \
 src/opus_decoder.c \
 src/opus_encoder.c \
 src/opus_multistream.c \
+src/opus_multistream_encoder.c \
+src/opus_multistream_decoder.c \
 src/repacketizer.c
 
 OPUS_SOURCES_FLOAT = \
diff --git a/src/opus_multistream.c b/src/opus_multistream.c
index 9c427b5d..09c3639b 100644
--- a/src/opus_multistream.c
+++ b/src/opus_multistream.c
@@ -37,31 +37,8 @@
 #include "float_cast.h"
 #include "os_support.h"
 
-typedef struct ChannelLayout {
-   int nb_channels;
-   int nb_streams;
-   int nb_coupled_streams;
-   unsigned char mapping[256];
-} ChannelLayout;
 
-struct OpusMSEncoder {
-   ChannelLayout layout;
-   int bitrate;
-   /* Encoder states go here */
-};
-
-struct OpusMSDecoder {
-   ChannelLayout layout;
-   /* Decoder states go here */
-};
-
-#ifdef FIXED_POINT
-#define opus_encode_native opus_encode
-#else
-#define opus_encode_native opus_encode_float
-#endif
-
-static int validate_layout(const ChannelLayout *layout)
+int validate_layout(const ChannelLayout *layout)
 {
    int i, max_channel;
 
@@ -77,7 +54,7 @@ static int validate_layout(const ChannelLayout *layout)
 }
 
 
-static int get_left_channel(const ChannelLayout *layout, int stream_id, int prev)
+int get_left_channel(const ChannelLayout *layout, int stream_id, int prev)
 {
    int i;
    i = (prev<0) ? 0 : prev+1;
@@ -89,7 +66,7 @@ static int get_left_channel(const ChannelLayout *layout, int stream_id, int prev
    return -1;
 }
 
-static int get_right_channel(const ChannelLayout *layout, int stream_id, int prev)
+int get_right_channel(const ChannelLayout *layout, int stream_id, int prev)
 {
    int i;
    i = (prev<0) ? 0 : prev+1;
@@ -101,7 +78,7 @@ static int get_right_channel(const ChannelLayout *layout, int stream_id, int pre
    return -1;
 }
 
-static int get_mono_channel(const ChannelLayout *layout, int stream_id, int prev)
+int get_mono_channel(const ChannelLayout *layout, int stream_id, int prev)
 {
    int i;
    i = (prev<0) ? 0 : prev+1;
@@ -113,915 +90,3 @@ static int get_mono_channel(const ChannelLayout *layout, int stream_id, int prev
    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;
-}
-
-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);
-}
-
-
-
-int opus_multistream_encoder_init(
-      OpusMSEncoder *st,
-      opus_int32 Fs,
-      int channels,
-      int streams,
-      int coupled_streams,
-      const unsigned char *mapping,
-      int application
-)
-{
-   int coupled_size;
-   int mono_size;
-   int i, ret;
-   char *ptr;
-
-   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
-       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
-      return OPUS_BAD_ARG;
-
-   st->layout.nb_channels = channels;
-   st->layout.nb_streams = streams;
-   st->layout.nb_coupled_streams = coupled_streams;
-
-   for (i=0;i<st->layout.nb_channels;i++)
-      st->layout.mapping[i] = mapping[i];
-   if (!validate_layout(&st->layout) || !validate_encoder_layout(&st->layout))
-      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;
-      ptr += align(coupled_size);
-   }
-   for (;i<st->layout.nb_streams;i++)
-   {
-      ret = opus_encoder_init((OpusEncoder*)ptr, Fs, 1, application);
-      if(ret!=OPUS_OK)return ret;
-      ptr += align(mono_size);
-   }
-   return OPUS_OK;
-}
-
-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) ||
-       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
-   {
-      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;
-}
-
-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
-);
-
-/* Max size in case the encoder decides to return three frames */
-#define MS_FRAME_TMP (3*1275+7)
-static int opus_multistream_encode_native
-(
-    OpusMSEncoder *st,
-    opus_copy_channel_in_func copy_channel_in,
-    const void *pcm,
-    int frame_size,
-    unsigned char *data,
-    opus_int32 max_data_bytes
-)
-{
-   opus_int32 Fs;
-   int coupled_size;
-   int mono_size;
-   int s;
-   char *ptr;
-   int tot_size;
-   VARDECL(opus_val16, buf);
-   unsigned char tmp_data[MS_FRAME_TMP];
-   OpusRepacketizer rp;
-   ALLOC_STACK;
-
-   ptr = (char*)st + align(sizeof(OpusMSEncoder));
-   opus_encoder_ctl((OpusEncoder*)ptr, OPUS_GET_SAMPLE_RATE(&Fs));
-   /* Validate frame_size before using it to allocate stack space.
-      This mirrors the checks in opus_encode[_float](). */
-   if (400*frame_size != Fs && 200*frame_size != Fs &&
-       100*frame_size != Fs &&  50*frame_size != Fs &&
-        25*frame_size != Fs &&  50*frame_size != 3*Fs)
-   {
-      RESTORE_STACK;
-      return OPUS_BAD_ARG;
-   }
-   ALLOC(buf, 2*frame_size, opus_val16);
-   coupled_size = opus_encoder_get_size(2);
-   mono_size = opus_encoder_get_size(1);
-
-   if (max_data_bytes < 4*st->layout.nb_streams-1)
-   {
-      RESTORE_STACK;
-      return OPUS_BUFFER_TOO_SMALL;
-   }
-   /* Counting ToC */
-   tot_size = 0;
-   for (s=0;s<st->layout.nb_streams;s++)
-   {
-      OpusEncoder *enc;
-      int len;
-      int curr_max;
-
-      opus_repacketizer_init(&rp);
-      enc = (OpusEncoder*)ptr;
-      if (s < st->layout.nb_coupled_streams)
-      {
-         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);
-      } else {
-         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);
-      }
-      /* 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);
-      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) */
-      opus_repacketizer_cat(&rp, tmp_data, len);
-      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);
-      data += len;
-      tot_size += len;
-   }
-   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;
-   int 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;
-   int 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);
-}
-
-#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);
-}
-#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);
-}
-
-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);
-}
-#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:
-   {
-      int chan, s;
-      opus_int32 value = va_arg(ap, opus_int32);
-      chan = st->layout.nb_streams + st->layout.nb_coupled_streams;
-      value /= chan;
-      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, request, value * (s < st->layout.nb_coupled_streams ? 2 : 1));
-      }
-   }
-   break;
-   case OPUS_GET_BITRATE_REQUEST:
-   {
-      int s;
-      opus_int32 *value = va_arg(ap, opus_int32*);
-      *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:
-   {
-      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;
-      *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_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:
-   {
-      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**);
-      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;
-   default:
-      ret = OPUS_UNIMPLEMENTED;
-      break;
-   }
-
-   va_end(ap);
-   return ret;
-}
-
-void opus_multistream_encoder_destroy(OpusMSEncoder *st)
-{
-    opus_free(st);
-}
-
-
-/* DECODER */
-
-opus_int32 opus_multistream_decoder_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_decoder_get_size(2);
-   mono_size = opus_decoder_get_size(1);
-   return align(sizeof(OpusMSDecoder))
-         + nb_coupled_streams * align(coupled_size)
-         + (nb_streams-nb_coupled_streams) * align(mono_size);
-}
-
-int opus_multistream_decoder_init(
-      OpusMSDecoder *st,
-      opus_int32 Fs,
-      int channels,
-      int streams,
-      int coupled_streams,
-      const unsigned char *mapping
-)
-{
-   int coupled_size;
-   int mono_size;
-   int i, ret;
-   char *ptr;
-
-   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
-       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
-      return OPUS_BAD_ARG;
-
-   st->layout.nb_channels = channels;
-   st->layout.nb_streams = streams;
-   st->layout.nb_coupled_streams = coupled_streams;
-
-   for (i=0;i<st->layout.nb_channels;i++)
-      st->layout.mapping[i] = mapping[i];
-   if (!validate_layout(&st->layout))
-      return OPUS_BAD_ARG;
-
-   ptr = (char*)st + align(sizeof(OpusMSDecoder));
-   coupled_size = opus_decoder_get_size(2);
-   mono_size = opus_decoder_get_size(1);
-
-   for (i=0;i<st->layout.nb_coupled_streams;i++)
-   {
-      ret=opus_decoder_init((OpusDecoder*)ptr, Fs, 2);
-      if(ret!=OPUS_OK)return ret;
-      ptr += align(coupled_size);
-   }
-   for (;i<st->layout.nb_streams;i++)
-   {
-      ret=opus_decoder_init((OpusDecoder*)ptr, Fs, 1);
-      if(ret!=OPUS_OK)return ret;
-      ptr += align(mono_size);
-   }
-   return OPUS_OK;
-}
-
-
-OpusMSDecoder *opus_multistream_decoder_create(
-      opus_int32 Fs,
-      int channels,
-      int streams,
-      int coupled_streams,
-      const unsigned char *mapping,
-      int *error
-)
-{
-   int ret;
-   OpusMSDecoder *st;
-   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
-       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
-   {
-      if (error)
-         *error = OPUS_BAD_ARG;
-      return NULL;
-   }
-   st = (OpusMSDecoder *)opus_alloc(opus_multistream_decoder_get_size(streams, coupled_streams));
-   if (st==NULL)
-   {
-      if (error)
-         *error = OPUS_ALLOC_FAIL;
-      return NULL;
-   }
-   ret = opus_multistream_decoder_init(st, Fs, channels, streams, coupled_streams, mapping);
-   if (error)
-      *error = ret;
-   if (ret != OPUS_OK)
-   {
-      opus_free(st);
-      st = NULL;
-   }
-   return st;
-}
-
-typedef void (*opus_copy_channel_out_func)(
-  void *dst,
-  int dst_stride,
-  int dst_channel,
-  const opus_val16 *src,
-  int src_stride,
-  int frame_size
-);
-
-static int opus_multistream_decode_native(
-      OpusMSDecoder *st,
-      const unsigned char *data,
-      opus_int32 len,
-      void *pcm,
-      opus_copy_channel_out_func copy_channel_out,
-      int frame_size,
-      int decode_fec
-)
-{
-   opus_int32 Fs;
-   int coupled_size;
-   int mono_size;
-   int s, c;
-   char *ptr;
-   int do_plc=0;
-   VARDECL(opus_val16, buf);
-   ALLOC_STACK;
-
-   /* Limit frame_size to avoid excessive stack allocations. */
-   opus_multistream_decoder_ctl(st, OPUS_GET_SAMPLE_RATE(&Fs));
-   frame_size = IMIN(frame_size, Fs/25*3);
-   ALLOC(buf, 2*frame_size, opus_val16);
-   ptr = (char*)st + align(sizeof(OpusMSDecoder));
-   coupled_size = opus_decoder_get_size(2);
-   mono_size = opus_decoder_get_size(1);
-
-   if (len==0)
-      do_plc = 1;
-   if (len < 0)
-      return OPUS_BAD_ARG;
-   if (!do_plc && len < 2*st->layout.nb_streams-1)
-      return OPUS_INVALID_PACKET;
-   for (s=0;s<st->layout.nb_streams;s++)
-   {
-      OpusDecoder *dec;
-      int packet_offset, ret;
-
-      dec = (OpusDecoder*)ptr;
-      ptr += (s < st->layout.nb_coupled_streams) ? align(coupled_size) : align(mono_size);
-
-      if (!do_plc && len<=0)
-      {
-         RESTORE_STACK;
-         return OPUS_INVALID_PACKET;
-      }
-      packet_offset = 0;
-      ret = opus_decode_native(dec, data, len, buf, frame_size, decode_fec, s!=st->layout.nb_streams-1, &packet_offset);
-      data += packet_offset;
-      len -= packet_offset;
-      if (ret > frame_size)
-      {
-         RESTORE_STACK;
-         return OPUS_BUFFER_TOO_SMALL;
-      }
-      if (s>0 && ret != frame_size)
-      {
-         RESTORE_STACK;
-         return OPUS_INVALID_PACKET;
-      }
-      if (ret <= 0)
-      {
-         RESTORE_STACK;
-         return ret;
-      }
-      frame_size = ret;
-      if (s < st->layout.nb_coupled_streams)
-      {
-         int chan, prev;
-         prev = -1;
-         /* Copy "left" audio to the channel(s) where it belongs */
-         while ( (chan = get_left_channel(&st->layout, s, prev)) != -1)
-         {
-            (*copy_channel_out)(pcm, st->layout.nb_channels, chan,
-               buf, 2, frame_size);
-            prev = chan;
-         }
-         prev = -1;
-         /* Copy "right" audio to the channel(s) where it belongs */
-         while ( (chan = get_right_channel(&st->layout, s, prev)) != -1)
-         {
-            (*copy_channel_out)(pcm, st->layout.nb_channels, chan,
-               buf+1, 2, frame_size);
-            prev = chan;
-         }
-      } else {
-         int chan, prev;
-         prev = -1;
-         /* Copy audio to the channel(s) where it belongs */
-         while ( (chan = get_mono_channel(&st->layout, s, prev)) != -1)
-         {
-            (*copy_channel_out)(pcm, st->layout.nb_channels, chan,
-               buf, 1, frame_size);
-            prev = chan;
-         }
-      }
-   }
-   /* Handle muted channels */
-   for (c=0;c<st->layout.nb_channels;c++)
-   {
-      if (st->layout.mapping[c] == 255)
-      {
-         (*copy_channel_out)(pcm, st->layout.nb_channels, c,
-            NULL, 0, frame_size);
-      }
-   }
-   RESTORE_STACK;
-   return frame_size;
-}
-
-#if !defined(DISABLE_FLOAT_API)
-static void opus_copy_channel_out_float(
-  void *dst,
-  int dst_stride,
-  int dst_channel,
-  const opus_val16 *src,
-  int src_stride,
-  int frame_size
-)
-{
-   float *float_dst;
-   int i;
-   float_dst = (float*)dst;
-   if (src != NULL)
-   {
-      for (i=0;i<frame_size;i++)
-#if defined(FIXED_POINT)
-         float_dst[i*dst_stride+dst_channel] = (1/32768.f)*src[i*src_stride];
-#else
-         float_dst[i*dst_stride+dst_channel] = src[i*src_stride];
-#endif
-   }
-   else
-   {
-      for (i=0;i<frame_size;i++)
-         float_dst[i*dst_stride+dst_channel] = 0;
-   }
-}
-#endif
-
-static void opus_copy_channel_out_short(
-  void *dst,
-  int dst_stride,
-  int dst_channel,
-  const opus_val16 *src,
-  int src_stride,
-  int frame_size
-)
-{
-   opus_int16 *short_dst;
-   int i;
-   short_dst = (opus_int16*)dst;
-   if (src != NULL)
-   {
-      for (i=0;i<frame_size;i++)
-#if defined(FIXED_POINT)
-         short_dst[i*dst_stride+dst_channel] = src[i*src_stride];
-#else
-         short_dst[i*dst_stride+dst_channel] = FLOAT2INT16(src[i*src_stride]);
-#endif
-   }
-   else
-   {
-      for (i=0;i<frame_size;i++)
-         short_dst[i*dst_stride+dst_channel] = 0;
-   }
-}
-
-
-
-#ifdef FIXED_POINT
-int opus_multistream_decode(
-      OpusMSDecoder *st,
-      const unsigned char *data,
-      opus_int32 len,
-      opus_int16 *pcm,
-      int frame_size,
-      int decode_fec
-)
-{
-   return opus_multistream_decode_native(st, data, len,
-       pcm, opus_copy_channel_out_short, frame_size, decode_fec);
-}
-
-#ifndef DISABLE_FLOAT_API
-int opus_multistream_decode_float(OpusMSDecoder *st, const unsigned char *data,
-      opus_int32 len, float *pcm, int frame_size, int decode_fec)
-{
-   return opus_multistream_decode_native(st, data, len,
-       pcm, opus_copy_channel_out_float, frame_size, decode_fec);
-}
-#endif
-
-#else
-
-int opus_multistream_decode(OpusMSDecoder *st, const unsigned char *data,
-      opus_int32 len, opus_int16 *pcm, int frame_size, int decode_fec)
-{
-   return opus_multistream_decode_native(st, data, len,
-       pcm, opus_copy_channel_out_short, frame_size, decode_fec);
-}
-
-int opus_multistream_decode_float(
-      OpusMSDecoder *st,
-      const unsigned char *data,
-      opus_int32 len,
-      float *pcm,
-      int frame_size,
-      int decode_fec
-)
-{
-   return opus_multistream_decode_native(st, data, len,
-       pcm, opus_copy_channel_out_float, frame_size, decode_fec);
-}
-#endif
-
-int opus_multistream_decoder_ctl(OpusMSDecoder *st, int request, ...)
-{
-   va_list ap;
-   int coupled_size, mono_size;
-   char *ptr;
-   int ret = OPUS_OK;
-
-   va_start(ap, request);
-
-   coupled_size = opus_decoder_get_size(2);
-   mono_size = opus_decoder_get_size(1);
-   ptr = (char*)st + align(sizeof(OpusMSDecoder));
-   switch (request)
-   {
-       case OPUS_GET_BANDWIDTH_REQUEST:
-       case OPUS_GET_SAMPLE_RATE_REQUEST:
-       {
-          OpusDecoder *dec;
-          /* For int32* GET params, just query the first stream */
-          opus_int32 *value = va_arg(ap, opus_int32*);
-          dec = (OpusDecoder*)ptr;
-          ret = opus_decoder_ctl(dec, request, value);
-       }
-       break;
-       case OPUS_GET_FINAL_RANGE_REQUEST:
-       {
-          int s;
-          opus_uint32 *value = va_arg(ap, opus_uint32*);
-          opus_uint32 tmp;
-          *value = 0;
-          for (s=0;s<st->layout.nb_streams;s++)
-          {
-             OpusDecoder *dec;
-             dec = (OpusDecoder*)ptr;
-             if (s < st->layout.nb_coupled_streams)
-                ptr += align(coupled_size);
-             else
-                ptr += align(mono_size);
-             ret = opus_decoder_ctl(dec, request, &tmp);
-             if (ret != OPUS_OK) break;
-             *value ^= tmp;
-          }
-       }
-       break;
-       case OPUS_RESET_STATE:
-       {
-          int s;
-          for (s=0;s<st->layout.nb_streams;s++)
-          {
-             OpusDecoder *dec;
-
-             dec = (OpusDecoder*)ptr;
-             if (s < st->layout.nb_coupled_streams)
-                ptr += align(coupled_size);
-             else
-                ptr += align(mono_size);
-             ret = opus_decoder_ctl(dec, OPUS_RESET_STATE);
-             if (ret != OPUS_OK)
-                break;
-          }
-       }
-       break;
-       case OPUS_MULTISTREAM_GET_DECODER_STATE_REQUEST:
-       {
-          int s;
-          opus_int32 stream_id;
-          OpusDecoder **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, OpusDecoder**);
-          for (s=0;s<stream_id;s++)
-          {
-             if (s < st->layout.nb_coupled_streams)
-                ptr += align(coupled_size);
-             else
-                ptr += align(mono_size);
-          }
-          *value = (OpusDecoder*)ptr;
-       }
-       break;
-       case OPUS_SET_GAIN_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++)
-          {
-             OpusDecoder *dec;
-
-             dec = (OpusDecoder*)ptr;
-             if (s < st->layout.nb_coupled_streams)
-                ptr += align(coupled_size);
-             else
-                ptr += align(mono_size);
-             ret = opus_decoder_ctl(dec, request, value);
-             if (ret != OPUS_OK)
-                break;
-          }
-       }
-       break;
-       default:
-          ret = OPUS_UNIMPLEMENTED;
-       break;
-   }
-
-   va_end(ap);
-   return ret;
-}
-
-
-void opus_multistream_decoder_destroy(OpusMSDecoder *st)
-{
-    opus_free(st);
-}
diff --git a/src/opus_multistream_decoder.c b/src/opus_multistream_decoder.c
new file mode 100644
index 00000000..ed7cb559
--- /dev/null
+++ b/src/opus_multistream_decoder.c
@@ -0,0 +1,485 @@
+/* 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"
+
+struct OpusMSDecoder {
+   ChannelLayout layout;
+   /* Decoder states go here */
+};
+
+
+
+
+/* DECODER */
+
+opus_int32 opus_multistream_decoder_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_decoder_get_size(2);
+   mono_size = opus_decoder_get_size(1);
+   return align(sizeof(OpusMSDecoder))
+         + nb_coupled_streams * align(coupled_size)
+         + (nb_streams-nb_coupled_streams) * align(mono_size);
+}
+
+int opus_multistream_decoder_init(
+      OpusMSDecoder *st,
+      opus_int32 Fs,
+      int channels,
+      int streams,
+      int coupled_streams,
+      const unsigned char *mapping
+)
+{
+   int coupled_size;
+   int mono_size;
+   int i, ret;
+   char *ptr;
+
+   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
+       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
+      return OPUS_BAD_ARG;
+
+   st->layout.nb_channels = channels;
+   st->layout.nb_streams = streams;
+   st->layout.nb_coupled_streams = coupled_streams;
+
+   for (i=0;i<st->layout.nb_channels;i++)
+      st->layout.mapping[i] = mapping[i];
+   if (!validate_layout(&st->layout))
+      return OPUS_BAD_ARG;
+
+   ptr = (char*)st + align(sizeof(OpusMSDecoder));
+   coupled_size = opus_decoder_get_size(2);
+   mono_size = opus_decoder_get_size(1);
+
+   for (i=0;i<st->layout.nb_coupled_streams;i++)
+   {
+      ret=opus_decoder_init((OpusDecoder*)ptr, Fs, 2);
+      if(ret!=OPUS_OK)return ret;
+      ptr += align(coupled_size);
+   }
+   for (;i<st->layout.nb_streams;i++)
+   {
+      ret=opus_decoder_init((OpusDecoder*)ptr, Fs, 1);
+      if(ret!=OPUS_OK)return ret;
+      ptr += align(mono_size);
+   }
+   return OPUS_OK;
+}
+
+
+OpusMSDecoder *opus_multistream_decoder_create(
+      opus_int32 Fs,
+      int channels,
+      int streams,
+      int coupled_streams,
+      const unsigned char *mapping,
+      int *error
+)
+{
+   int ret;
+   OpusMSDecoder *st;
+   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
+       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
+   {
+      if (error)
+         *error = OPUS_BAD_ARG;
+      return NULL;
+   }
+   st = (OpusMSDecoder *)opus_alloc(opus_multistream_decoder_get_size(streams, coupled_streams));
+   if (st==NULL)
+   {
+      if (error)
+         *error = OPUS_ALLOC_FAIL;
+      return NULL;
+   }
+   ret = opus_multistream_decoder_init(st, Fs, channels, streams, coupled_streams, mapping);
+   if (error)
+      *error = ret;
+   if (ret != OPUS_OK)
+   {
+      opus_free(st);
+      st = NULL;
+   }
+   return st;
+}
+
+typedef void (*opus_copy_channel_out_func)(
+  void *dst,
+  int dst_stride,
+  int dst_channel,
+  const opus_val16 *src,
+  int src_stride,
+  int frame_size
+);
+
+static int opus_multistream_decode_native(
+      OpusMSDecoder *st,
+      const unsigned char *data,
+      opus_int32 len,
+      void *pcm,
+      opus_copy_channel_out_func copy_channel_out,
+      int frame_size,
+      int decode_fec
+)
+{
+   opus_int32 Fs;
+   int coupled_size;
+   int mono_size;
+   int s, c;
+   char *ptr;
+   int do_plc=0;
+   VARDECL(opus_val16, buf);
+   ALLOC_STACK;
+
+   /* Limit frame_size to avoid excessive stack allocations. */
+   opus_multistream_decoder_ctl(st, OPUS_GET_SAMPLE_RATE(&Fs));
+   frame_size = IMIN(frame_size, Fs/25*3);
+   ALLOC(buf, 2*frame_size, opus_val16);
+   ptr = (char*)st + align(sizeof(OpusMSDecoder));
+   coupled_size = opus_decoder_get_size(2);
+   mono_size = opus_decoder_get_size(1);
+
+   if (len==0)
+      do_plc = 1;
+   if (len < 0)
+      return OPUS_BAD_ARG;
+   if (!do_plc && len < 2*st->layout.nb_streams-1)
+      return OPUS_INVALID_PACKET;
+   for (s=0;s<st->layout.nb_streams;s++)
+   {
+      OpusDecoder *dec;
+      int packet_offset, ret;
+
+      dec = (OpusDecoder*)ptr;
+      ptr += (s < st->layout.nb_coupled_streams) ? align(coupled_size) : align(mono_size);
+
+      if (!do_plc && len<=0)
+      {
+         RESTORE_STACK;
+         return OPUS_INVALID_PACKET;
+      }
+      packet_offset = 0;
+      ret = opus_decode_native(dec, data, len, buf, frame_size, decode_fec, s!=st->layout.nb_streams-1, &packet_offset);
+      data += packet_offset;
+      len -= packet_offset;
+      if (ret > frame_size)
+      {
+         RESTORE_STACK;
+         return OPUS_BUFFER_TOO_SMALL;
+      }
+      if (s>0 && ret != frame_size)
+      {
+         RESTORE_STACK;
+         return OPUS_INVALID_PACKET;
+      }
+      if (ret <= 0)
+      {
+         RESTORE_STACK;
+         return ret;
+      }
+      frame_size = ret;
+      if (s < st->layout.nb_coupled_streams)
+      {
+         int chan, prev;
+         prev = -1;
+         /* Copy "left" audio to the channel(s) where it belongs */
+         while ( (chan = get_left_channel(&st->layout, s, prev)) != -1)
+         {
+            (*copy_channel_out)(pcm, st->layout.nb_channels, chan,
+               buf, 2, frame_size);
+            prev = chan;
+         }
+         prev = -1;
+         /* Copy "right" audio to the channel(s) where it belongs */
+         while ( (chan = get_right_channel(&st->layout, s, prev)) != -1)
+         {
+            (*copy_channel_out)(pcm, st->layout.nb_channels, chan,
+               buf+1, 2, frame_size);
+            prev = chan;
+         }
+      } else {
+         int chan, prev;
+         prev = -1;
+         /* Copy audio to the channel(s) where it belongs */
+         while ( (chan = get_mono_channel(&st->layout, s, prev)) != -1)
+         {
+            (*copy_channel_out)(pcm, st->layout.nb_channels, chan,
+               buf, 1, frame_size);
+            prev = chan;
+         }
+      }
+   }
+   /* Handle muted channels */
+   for (c=0;c<st->layout.nb_channels;c++)
+   {
+      if (st->layout.mapping[c] == 255)
+      {
+         (*copy_channel_out)(pcm, st->layout.nb_channels, c,
+            NULL, 0, frame_size);
+      }
+   }
+   RESTORE_STACK;
+   return frame_size;
+}
+
+#if !defined(DISABLE_FLOAT_API)
+static void opus_copy_channel_out_float(
+  void *dst,
+  int dst_stride,
+  int dst_channel,
+  const opus_val16 *src,
+  int src_stride,
+  int frame_size
+)
+{
+   float *float_dst;
+   int i;
+   float_dst = (float*)dst;
+   if (src != NULL)
+   {
+      for (i=0;i<frame_size;i++)
+#if defined(FIXED_POINT)
+         float_dst[i*dst_stride+dst_channel] = (1/32768.f)*src[i*src_stride];
+#else
+         float_dst[i*dst_stride+dst_channel] = src[i*src_stride];
+#endif
+   }
+   else
+   {
+      for (i=0;i<frame_size;i++)
+         float_dst[i*dst_stride+dst_channel] = 0;
+   }
+}
+#endif
+
+static void opus_copy_channel_out_short(
+  void *dst,
+  int dst_stride,
+  int dst_channel,
+  const opus_val16 *src,
+  int src_stride,
+  int frame_size
+)
+{
+   opus_int16 *short_dst;
+   int i;
+   short_dst = (opus_int16*)dst;
+   if (src != NULL)
+   {
+      for (i=0;i<frame_size;i++)
+#if defined(FIXED_POINT)
+         short_dst[i*dst_stride+dst_channel] = src[i*src_stride];
+#else
+         short_dst[i*dst_stride+dst_channel] = FLOAT2INT16(src[i*src_stride]);
+#endif
+   }
+   else
+   {
+      for (i=0;i<frame_size;i++)
+         short_dst[i*dst_stride+dst_channel] = 0;
+   }
+}
+
+
+
+#ifdef FIXED_POINT
+int opus_multistream_decode(
+      OpusMSDecoder *st,
+      const unsigned char *data,
+      opus_int32 len,
+      opus_int16 *pcm,
+      int frame_size,
+      int decode_fec
+)
+{
+   return opus_multistream_decode_native(st, data, len,
+       pcm, opus_copy_channel_out_short, frame_size, decode_fec);
+}
+
+#ifndef DISABLE_FLOAT_API
+int opus_multistream_decode_float(OpusMSDecoder *st, const unsigned char *data,
+      opus_int32 len, float *pcm, int frame_size, int decode_fec)
+{
+   return opus_multistream_decode_native(st, data, len,
+       pcm, opus_copy_channel_out_float, frame_size, decode_fec);
+}
+#endif
+
+#else
+
+int opus_multistream_decode(OpusMSDecoder *st, const unsigned char *data,
+      opus_int32 len, opus_int16 *pcm, int frame_size, int decode_fec)
+{
+   return opus_multistream_decode_native(st, data, len,
+       pcm, opus_copy_channel_out_short, frame_size, decode_fec);
+}
+
+int opus_multistream_decode_float(
+      OpusMSDecoder *st,
+      const unsigned char *data,
+      opus_int32 len,
+      float *pcm,
+      int frame_size,
+      int decode_fec
+)
+{
+   return opus_multistream_decode_native(st, data, len,
+       pcm, opus_copy_channel_out_float, frame_size, decode_fec);
+}
+#endif
+
+int opus_multistream_decoder_ctl(OpusMSDecoder *st, int request, ...)
+{
+   va_list ap;
+   int coupled_size, mono_size;
+   char *ptr;
+   int ret = OPUS_OK;
+
+   va_start(ap, request);
+
+   coupled_size = opus_decoder_get_size(2);
+   mono_size = opus_decoder_get_size(1);
+   ptr = (char*)st + align(sizeof(OpusMSDecoder));
+   switch (request)
+   {
+       case OPUS_GET_BANDWIDTH_REQUEST:
+       case OPUS_GET_SAMPLE_RATE_REQUEST:
+       {
+          OpusDecoder *dec;
+          /* For int32* GET params, just query the first stream */
+          opus_int32 *value = va_arg(ap, opus_int32*);
+          dec = (OpusDecoder*)ptr;
+          ret = opus_decoder_ctl(dec, request, value);
+       }
+       break;
+       case OPUS_GET_FINAL_RANGE_REQUEST:
+       {
+          int s;
+          opus_uint32 *value = va_arg(ap, opus_uint32*);
+          opus_uint32 tmp;
+          *value = 0;
+          for (s=0;s<st->layout.nb_streams;s++)
+          {
+             OpusDecoder *dec;
+             dec = (OpusDecoder*)ptr;
+             if (s < st->layout.nb_coupled_streams)
+                ptr += align(coupled_size);
+             else
+                ptr += align(mono_size);
+             ret = opus_decoder_ctl(dec, request, &tmp);
+             if (ret != OPUS_OK) break;
+             *value ^= tmp;
+          }
+       }
+       break;
+       case OPUS_RESET_STATE:
+       {
+          int s;
+          for (s=0;s<st->layout.nb_streams;s++)
+          {
+             OpusDecoder *dec;
+
+             dec = (OpusDecoder*)ptr;
+             if (s < st->layout.nb_coupled_streams)
+                ptr += align(coupled_size);
+             else
+                ptr += align(mono_size);
+             ret = opus_decoder_ctl(dec, OPUS_RESET_STATE);
+             if (ret != OPUS_OK)
+                break;
+          }
+       }
+       break;
+       case OPUS_MULTISTREAM_GET_DECODER_STATE_REQUEST:
+       {
+          int s;
+          opus_int32 stream_id;
+          OpusDecoder **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, OpusDecoder**);
+          for (s=0;s<stream_id;s++)
+          {
+             if (s < st->layout.nb_coupled_streams)
+                ptr += align(coupled_size);
+             else
+                ptr += align(mono_size);
+          }
+          *value = (OpusDecoder*)ptr;
+       }
+       break;
+       case OPUS_SET_GAIN_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++)
+          {
+             OpusDecoder *dec;
+
+             dec = (OpusDecoder*)ptr;
+             if (s < st->layout.nb_coupled_streams)
+                ptr += align(coupled_size);
+             else
+                ptr += align(mono_size);
+             ret = opus_decoder_ctl(dec, request, value);
+             if (ret != OPUS_OK)
+                break;
+          }
+       }
+       break;
+       default:
+          ret = OPUS_UNIMPLEMENTED;
+       break;
+   }
+
+   va_end(ap);
+   return ret;
+}
+
+
+void opus_multistream_decoder_destroy(OpusMSDecoder *st)
+{
+    opus_free(st);
+}
diff --git a/src/opus_multistream_encoder.c b/src/opus_multistream_encoder.c
new file mode 100644
index 00000000..c5f37a0e
--- /dev/null
+++ b/src/opus_multistream_encoder.c
@@ -0,0 +1,526 @@
+/* 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"
+
+struct OpusMSEncoder {
+   ChannelLayout layout;
+   int bitrate;
+   /* Encoder states go here */
+};
+
+#ifdef FIXED_POINT
+#define opus_encode_native opus_encode
+#else
+#define opus_encode_native opus_encode_float
+#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;
+}
+
+
+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);
+}
+
+
+
+int opus_multistream_encoder_init(
+      OpusMSEncoder *st,
+      opus_int32 Fs,
+      int channels,
+      int streams,
+      int coupled_streams,
+      const unsigned char *mapping,
+      int application
+)
+{
+   int coupled_size;
+   int mono_size;
+   int i, ret;
+   char *ptr;
+
+   if ((channels>255) || (channels<1) || (coupled_streams>streams) ||
+       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
+      return OPUS_BAD_ARG;
+
+   st->layout.nb_channels = channels;
+   st->layout.nb_streams = streams;
+   st->layout.nb_coupled_streams = coupled_streams;
+
+   for (i=0;i<st->layout.nb_channels;i++)
+      st->layout.mapping[i] = mapping[i];
+   if (!validate_layout(&st->layout) || !validate_encoder_layout(&st->layout))
+      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;
+      ptr += align(coupled_size);
+   }
+   for (;i<st->layout.nb_streams;i++)
+   {
+      ret = opus_encoder_init((OpusEncoder*)ptr, Fs, 1, application);
+      if(ret!=OPUS_OK)return ret;
+      ptr += align(mono_size);
+   }
+   return OPUS_OK;
+}
+
+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) ||
+       (coupled_streams+streams>255) || (streams<1) || (coupled_streams<0))
+   {
+      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;
+}
+
+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
+);
+
+/* Max size in case the encoder decides to return three frames */
+#define MS_FRAME_TMP (3*1275+7)
+static int opus_multistream_encode_native
+(
+    OpusMSEncoder *st,
+    opus_copy_channel_in_func copy_channel_in,
+    const void *pcm,
+    int frame_size,
+    unsigned char *data,
+    opus_int32 max_data_bytes
+)
+{
+   opus_int32 Fs;
+   int coupled_size;
+   int mono_size;
+   int s;
+   char *ptr;
+   int tot_size;
+   VARDECL(opus_val16, buf);
+   unsigned char tmp_data[MS_FRAME_TMP];
+   OpusRepacketizer rp;
+   ALLOC_STACK;
+
+   ptr = (char*)st + align(sizeof(OpusMSEncoder));
+   opus_encoder_ctl((OpusEncoder*)ptr, OPUS_GET_SAMPLE_RATE(&Fs));
+   /* Validate frame_size before using it to allocate stack space.
+      This mirrors the checks in opus_encode[_float](). */
+   if (400*frame_size != Fs && 200*frame_size != Fs &&
+       100*frame_size != Fs &&  50*frame_size != Fs &&
+        25*frame_size != Fs &&  50*frame_size != 3*Fs)
+   {
+      RESTORE_STACK;
+      return OPUS_BAD_ARG;
+   }
+   ALLOC(buf, 2*frame_size, opus_val16);
+   coupled_size = opus_encoder_get_size(2);
+   mono_size = opus_encoder_get_size(1);
+
+   if (max_data_bytes < 4*st->layout.nb_streams-1)
+   {
+      RESTORE_STACK;
+      return OPUS_BUFFER_TOO_SMALL;
+   }
+   /* Counting ToC */
+   tot_size = 0;
+   for (s=0;s<st->layout.nb_streams;s++)
+   {
+      OpusEncoder *enc;
+      int len;
+      int curr_max;
+
+      opus_repacketizer_init(&rp);
+      enc = (OpusEncoder*)ptr;
+      if (s < st->layout.nb_coupled_streams)
+      {
+         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);
+      } else {
+         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);
+      }
+      /* 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);
+      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) */
+      opus_repacketizer_cat(&rp, tmp_data, len);
+      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);
+      data += len;
+      tot_size += len;
+   }
+   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;
+   int 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;
+   int 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);
+}
+
+#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);
+}
+#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);
+}
+
+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);
+}
+#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:
+   {
+      int chan, s;
+      opus_int32 value = va_arg(ap, opus_int32);
+      chan = st->layout.nb_streams + st->layout.nb_coupled_streams;
+      value /= chan;
+      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, request, value * (s < st->layout.nb_coupled_streams ? 2 : 1));
+      }
+   }
+   break;
+   case OPUS_GET_BITRATE_REQUEST:
+   {
+      int s;
+      opus_int32 *value = va_arg(ap, opus_int32*);
+      *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:
+   {
+      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;
+      *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_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:
+   {
+      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**);
+      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;
+   default:
+      ret = OPUS_UNIMPLEMENTED;
+      break;
+   }
+
+   va_end(ap);
+   return ret;
+}
+
+void opus_multistream_encoder_destroy(OpusMSEncoder *st)
+{
+    opus_free(st);
+}
+
+
diff --git a/src/opus_private.h b/src/opus_private.h
index e4f4c76e..1362073c 100644
--- a/src/opus_private.h
+++ b/src/opus_private.h
@@ -40,6 +40,19 @@ struct OpusRepacketizer {
    int framesize;
 };
 
+typedef struct ChannelLayout {
+   int nb_channels;
+   int nb_streams;
+   int nb_coupled_streams;
+   unsigned char mapping[256];
+} ChannelLayout;
+
+int validate_layout(const ChannelLayout *layout);
+int get_left_channel(const ChannelLayout *layout, int stream_id, int prev);
+int get_right_channel(const ChannelLayout *layout, int stream_id, int prev);
+int get_mono_channel(const ChannelLayout *layout, int stream_id, int prev);
+
+
 
 #define MODE_SILK_ONLY          1000
 #define MODE_HYBRID             1001