Adds support for multi-stream encoding/decoding

Only tested for the single-stream case!

opus_headers.txt

@@ -1,3 +1,4 @@
 OPUS_HEAD = \
 src/opus.h \
+src/opus_multistream.h \
 src/opus_private.h

opus_sources.mk

@@ -1,4 +1,5 @@
 OPUS_SOURCES = src/opus.c \
 src/opus_decoder.c \
 src/opus_encoder.c \
+src/opus_multistream.c \
 src/repacketizer.c

src/opus.h

@@ -169,6 +169,8 @@ extern "C" {
 typedef struct OpusEncoder OpusEncoder;
 typedef struct OpusDecoder OpusDecoder;
 
+OPUS_EXPORT int opus_encoder_get_size(int channels);
+
 /*
  * There are two coding modes:
  * OPUS_APPLICATION_VOIP gives best quality at a given bitrate for voice
@@ -219,6 +221,10 @@ OPUS_EXPORT void opus_encoder_destroy(OpusEncoder *st);
 
 OPUS_EXPORT int opus_encoder_ctl(OpusEncoder *st, int request, ...);
 
+
+
+OPUS_EXPORT int opus_decoder_get_size(int channels);
+
 OPUS_EXPORT OpusDecoder *opus_decoder_create(
     int Fs,                     /* Sampling rate of output signal (Hz) */
     int channels                /* Number of channels (1/2) in output signal */

src/opus_decoder.c

@@ -626,23 +626,21 @@ int opus_packet_parse(const unsigned char *data, int len,
          out_toc, frames, size, payload_offset);
 }
 
-#ifdef FIXED_POINT
+int opus_decode_native(OpusDecoder *st, const unsigned char *data,
-int opus_decode(OpusDecoder *st, const unsigned char *data,
+      int len, opus_val16 *pcm, int frame_size, int decode_fec, int self_delimited, int *packet_offset)
-      int len, opus_val16 *pcm, int frame_size, int decode_fec)
-#else
-int opus_decode_float(OpusDecoder *st, const unsigned char *data,
-		int len, opus_val16 *pcm, int frame_size, int decode_fec)
-#endif
 {
 	int i, nb_samples;
 	int count, offset;
 	unsigned char toc;
+	int tot_offset;
 	/* 48 x 2.5 ms = 120 ms */
 	short size[48];
 	if (len==0 || data==NULL)
 	    return opus_decode_frame(st, NULL, 0, pcm, frame_size, 0);
 	else if (len<0)
 		return OPUS_BAD_ARG;
+
+	tot_offset = 0;
 	st->mode = opus_packet_get_mode(data);
 	st->bandwidth = opus_packet_get_bandwidth(data);
 	st->frame_size = opus_packet_get_samples_per_frame(data, st->Fs);
@@ -653,6 +651,8 @@ int opus_decode_float(OpusDecoder *st, const unsigned char *data,
 	   return count;
 
 	data += offset;
+	tot_offset += offset;
+
 	if (count*st->frame_size > frame_size)
 		return OPUS_BAD_ARG;
 	nb_samples=0;
@@ -663,14 +663,23 @@ int opus_decode_float(OpusDecoder *st, const unsigned char *data,
 		if (ret<0)
 			return ret;
 		data += size[i];
+		tot_offset += size[i];
 		pcm += ret*st->channels;
 		nb_samples += ret;
 	}
+	if (packet_offset != NULL)
+	   *packet_offset = tot_offset;
 	return nb_samples;
 }
 
 #ifdef FIXED_POINT
 
+int opus_decode(OpusDecoder *st, const unsigned char *data,
+      int len, opus_val16 *pcm, int frame_size, int decode_fec)
+{
+   return opus_decode_native(st, data, len, pcm, frame_size, decode_fec, 0, NULL);
+}
+
 #ifndef DISABLE_FLOAT_API
 int opus_decode_float(OpusDecoder *st, const unsigned char *data,
       int len, float *pcm, int frame_size, int decode_fec)
@@ -681,7 +690,7 @@ int opus_decode_float(OpusDecoder *st, const unsigned char *data,
 
    ALLOC(out, frame_size*st->channels, opus_int16);
 
-   ret = opus_decode(st, data, len, out, frame_size, decode_fec);
+   ret = opus_decode_native(st, data, len, out, frame_size, decode_fec, 0, NULL);
    if (ret > 0)
    {
       for (i=0;i<ret*st->channels;i++)
@@ -692,6 +701,7 @@ int opus_decode_float(OpusDecoder *st, const unsigned char *data,
 }
 #endif
 
+
 #else
 int opus_decode(OpusDecoder *st, const unsigned char *data,
       int len, opus_int16 *pcm, int frame_size, int decode_fec)
@@ -702,7 +712,7 @@ int opus_decode(OpusDecoder *st, const unsigned char *data,
 
    ALLOC(out, frame_size*st->channels, float);
 
-   ret = opus_decode_float(st, data, len, out, frame_size, decode_fec);
+   ret = opus_decode_native(st, data, len, out, frame_size, decode_fec, 0, NULL);
    if (ret > 0)
    {
       for (i=0;i<ret*st->channels;i++)
@@ -711,6 +721,13 @@ int opus_decode(OpusDecoder *st, const unsigned char *data,
    RESTORE_STACK;
    return ret;
 }
+
+int opus_decode_float(OpusDecoder *st, const unsigned char *data,
+        int len, opus_val16 *pcm, int frame_size, int decode_fec)
+{
+   return opus_decode_native(st, data, len, pcm, frame_size, decode_fec, 0, NULL);
+}
+
 #endif
 
 int opus_decoder_ctl(OpusDecoder *st, int request, ...)

src/opus_multistream.c

@@ -0,0 +1,713 @@
+/* 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 FOUNDATION 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 "stdio.h"
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include "float_cast.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 i, max_channel;
+
+   max_channel = layout->nb_streams+layout->nb_coupled_streams;
+   if (max_channel>255)
+      return 0;
+   for (i=0;i<layout->nb_channels;i++)
+   {
+      if (layout->mapping[i] >= max_channel && layout->mapping[i] != 255)
+         return 0;
+   }
+   return 1;
+}
+
+
+static int get_left_channel(const ChannelLayout *layout, int stream_id, int prev)
+{
+   int i;
+   i = (prev<0) ? 0 : prev+1;
+   for (;i<layout->nb_channels;i++)
+   {
+      if (layout->mapping[i]==stream_id*2)
+         return i;
+   }
+   return -1;
+}
+
+static int get_right_channel(const ChannelLayout *layout, int stream_id, int prev)
+{
+   int i;
+   i = (prev<0) ? 0 : prev+1;
+   for (;i<layout->nb_channels;i++)
+   {
+      if (layout->mapping[i]==stream_id*2+1)
+         return i;
+   }
+   return -1;
+}
+
+static int get_mono_channel(const ChannelLayout *layout, int stream_id, int prev)
+{
+   int i;
+   i = (prev<0) ? 0 : prev+1;
+   for (;i<layout->nb_channels;i++)
+   {
+      if (layout->mapping[i]==2*layout->nb_coupled_streams+stream_id)
+         return i;
+   }
+   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;
+}
+
+int opus_multistream_encoder_get_size(int nb_streams, int nb_coupled_streams)
+{
+	int coupled_size;
+	int mono_size;
+
+	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,            /* Encoder state */
+      int Fs,                     /* Sampling rate of input signal (Hz) */
+      int channels,               /* Number of channels (1/2) in input signal */
+      int streams,
+      int coupled_streams,
+      unsigned char *mapping,
+      int application             /* Coding mode (OPUS_APPLICATION_VOIP/OPUS_APPLICATION_AUDIO) */
+)
+{
+   int coupled_size;
+   int mono_size;
+   int i;
+   char *ptr;
+
+   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++)
+   {
+      opus_encoder_init((OpusEncoder*)ptr, Fs, 2, application);
+      ptr += align(coupled_size);
+   }
+   for (;i<st->layout.nb_streams;i++)
+   {
+      opus_encoder_init((OpusEncoder*)ptr, Fs, 1, application);
+      ptr += align(mono_size);
+   }
+   return OPUS_OK;
+}
+
+OpusMSEncoder *opus_multistream_encoder_create(
+      int Fs,                     /* Sampling rate of input signal (Hz) */
+      int channels,               /* Number of channels (1/2) in input signal */
+      int streams,
+      int coupled_streams,
+      unsigned char *mapping,
+      int application             /* Coding mode (OPUS_APPLICATION_VOIP/OPUS_APPLICATION_AUDIO) */
+)
+{
+   OpusMSEncoder *st = malloc(opus_multistream_encoder_get_size(streams, coupled_streams));
+   if (st!=NULL)
+      opus_multistream_encoder_init(st, Fs, channels, streams, coupled_streams, mapping, application);
+   return st;
+}
+
+
+#ifdef FIXED_POINT
+int opus_multistream_encode(
+#else
+int opus_multistream_encode_float(
+#endif
+    OpusMSEncoder *st,            /* Encoder state */
+    const float *pcm,      /* Input signal (interleaved if 2 channels). length is frame_size*channels */
+    int frame_size,             /* Number of samples per frame of input signal */
+    unsigned char *data,        /* Output payload (no more than max_data_bytes long) */
+    int max_data_bytes          /* Allocated memory for payload; don't use for controlling bitrate */
+)
+{
+   int coupled_size;
+   int mono_size;
+   int s, i;
+   char *ptr;
+   int tot_size;
+   VARDECL(opus_val16, buf);
+   unsigned char tmp_data[1276];
+   ALLOC_STACK;
+
+   ALLOC(buf, 2*frame_size, opus_val16);
+   ptr = (char*)st + align(sizeof(OpusMSEncoder));
+   coupled_size = opus_encoder_get_size(2);
+   mono_size = opus_encoder_get_size(1);
+
+   if (max_data_bytes < 2*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;
+
+      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);
+         for (i=0;i<frame_size;i++)
+         {
+            buf[2*i] = pcm[st->layout.nb_channels*i+left];
+            buf[2*i+1] = pcm[st->layout.nb_channels*i+right];
+         }
+         ptr += align(coupled_size);
+      } else {
+         int chan = get_mono_channel(&st->layout, s, -1);
+         for (i=0;i<frame_size;i++)
+            buf[i] = pcm[st->layout.nb_channels*i+chan];
+         ptr += align(mono_size);
+      }
+      /* number of bytes left (+Toc) */
+      curr_max = max_data_bytes - tot_size;
+      /* Reserve one byte for the last stream and 2 for the others */
+      curr_max -= 2*(st->layout.nb_streams-s)-1;
+      len = opus_encode_native(enc, buf, frame_size, tmp_data, curr_max);
+      if (len<0)
+      {
+         RESTORE_STACK;
+         return len;
+      }
+      /* ToC first */
+      *data++ = tmp_data[0];
+      if (s != st->layout.nb_streams-1)
+      {
+         int tmp = encode_size(len-1, data);
+         data += tmp;
+         tot_size += tmp;
+      }
+      /* IMPORTANT: Here we assume that the encoder only returned one frame */
+      tot_size += len;
+      memcpy(data, &tmp_data[1], len-1);
+   }
+   RESTORE_STACK;
+   return tot_size;
+
+}
+
+#ifdef FIXED_POINT
+
+#ifndef DISABLE_FLOAT_API
+int opus_multistream_encode_float(
+    OpusMSEncoder *st,          /* Encoder state */
+    const float *pcm,           /* Input signal (interleaved if 2 channels). length is frame_size*channels */
+    int frame_size,             /* Number of samples per frame of input signal */
+    unsigned char *data,        /* Output payload (no more than max_data_bytes long) */
+    int max_data_bytes          /* Allocated memory for payload; don't use for controlling bitrate */
+)
+{
+   int i, ret;
+   VARDECL(opus_int16, in);
+   ALLOC_STACK;
+
+   ALLOC(in, frame_size*st->layout.nb_channels, opus_int16);
+
+   for (i=0;i<frame_size*st->layout.nb_channels;i++)
+      in[i] = FLOAT2INT16(pcm[i]);
+   ret = opus_multistream_encode(st, in, frame_size, data, max_data_bytes);
+   RESTORE_STACK;
+   return ret;
+}
+#endif
+
+#else
+
+int opus_multistream_encode(
+    OpusMSEncoder *st,          /* Encoder state */
+    const opus_int16 *pcm,      /* Input signal (interleaved if 2 channels). length is frame_size*channels */
+    int frame_size,             /* Number of samples per frame of input signal */
+    unsigned char *data,        /* Output payload (no more than max_data_bytes long) */
+    int max_data_bytes          /* Allocated memory for payload; don't use for controlling bitrate */
+)
+{
+   int i, ret;
+   VARDECL(float, in);
+   ALLOC_STACK;
+
+   ALLOC(in, frame_size*st->layout.nb_channels, float);
+
+   for (i=0;i<frame_size*st->layout.nb_channels;i++)
+      in[i] = (1./32768)*pcm[i];
+   ret = opus_multistream_encode_float(st, in, frame_size, data, max_data_bytes);
+   RESTORE_STACK;
+   return ret;
+}
+
+#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_uint32 value = va_arg(ap, opus_uint32);
+      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;
+         opus_encoder_ctl(enc, request, value * (s < st->layout.nb_coupled_streams ? 2 : 1));
+      }
+   }
+   break;
+   /* FIXME: Add missing ones */
+   case OPUS_GET_BITRATE_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:
+   {
+      int s;
+      /* This works for int32* params */
+      opus_uint32 value = va_arg(ap, opus_uint32);
+      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 < 0)
+            break;
+      }
+   }
+   break;
+   default:
+   {
+      int s;
+      /* This works for int32 params */
+      opus_uint32 value = va_arg(ap, opus_uint32);
+      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 < 0)
+            break;
+      }
+   }
+   break;
+   }
+
+   va_end(ap);
+   return ret;
+}
+
+void opus_multistream_encoder_destroy(OpusMSEncoder *st)
+{
+    free(st);
+}
+
+
+/* DECODER */
+
+int opus_multistream_decoder_get_size(int nb_streams, int nb_coupled_streams)
+{
+   int coupled_size;
+   int mono_size;
+
+   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,            /* Encoder state */
+      int Fs,                     /* Sampling rate of input signal (Hz) */
+      int channels,               /* Number of channels (1/2) in input signal */
+      int streams,
+      int coupled_streams,
+      unsigned char *mapping
+)
+{
+   int coupled_size;
+   int mono_size;
+   int i;
+   char *ptr;
+
+   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(OpusMSEncoder));
+   coupled_size = opus_decoder_get_size(2);
+   mono_size = opus_decoder_get_size(1);
+
+   for (i=0;i<st->layout.nb_coupled_streams;i++)
+   {
+      opus_decoder_init((OpusDecoder*)ptr, Fs, 2);
+      ptr += align(coupled_size);
+   }
+   for (;i<st->layout.nb_streams;i++)
+   {
+      opus_decoder_init((OpusDecoder*)ptr, Fs, 1);
+      ptr += align(mono_size);
+   }
+   return OPUS_OK;
+}
+
+
+OpusMSDecoder *opus_multistream_decoder_create(
+      int Fs,                     /* Sampling rate of input signal (Hz) */
+      int channels,               /* Number of channels (1/2) in input signal */
+      int streams,
+      int coupled_streams,
+      unsigned char *mapping
+)
+{
+   OpusMSDecoder *st = malloc(opus_multistream_decoder_get_size(streams, coupled_streams));
+   if (st!=NULL)
+      opus_multistream_decoder_init(st, Fs, channels, streams, coupled_streams, mapping);
+   return st;
+
+
+}
+
+static int opus_multistream_decode_native(
+      OpusMSDecoder *st,            /* Encoder state */
+      const unsigned char *data,
+      int len,
+      opus_val16 *pcm,
+      int frame_size,
+      int decode_fec
+)
+{
+   int coupled_size;
+   int mono_size;
+   int s, i, c;
+   char *ptr;
+   VARDECL(opus_val16, buf);
+   ALLOC_STACK;
+
+   ALLOC(buf, 2*frame_size, opus_val16);
+   ptr = (char*)st + align(sizeof(OpusMSEncoder));
+   coupled_size = opus_decoder_get_size(2);
+   mono_size = opus_decoder_get_size(1);
+
+   if (len < 2*st->layout.nb_streams-1)
+      return OPUS_BUFFER_TOO_SMALL;
+   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 (len<=0)
+      {
+         RESTORE_STACK;
+         return OPUS_CORRUPTED_DATA;
+      }
+      ret = opus_decode_native(dec, data, len, buf, frame_size, decode_fec, 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_CORRUPTED_DATA;
+      }
+      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)
+         {
+            for (i=0;i<frame_size;i++)
+               pcm[st->layout.nb_channels*i+chan] = buf[2*i];
+            prev = chan;
+         }
+         prev = -1;
+         /* Copy "right" audio to the channel(s) where it belongs */
+         while ( (chan = get_right_channel(&st->layout, s, prev)) != -1)
+         {
+            for (i=0;i<frame_size;i++)
+               pcm[st->layout.nb_channels*i+chan] = buf[2*i+1];
+            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)
+         {
+            for (i=0;i<frame_size;i++)
+               pcm[st->layout.nb_channels*i+chan] = buf[i];
+            prev = chan;
+         }
+      }
+   }
+   /* Handle muted channels */
+   for (c=0;c<st->layout.nb_channels;c++)
+   {
+      if (st->layout.mapping[c] == 255)
+      {
+         for (i=0;i<frame_size;i++)
+            pcm[st->layout.nb_channels*i+c] = 0;
+      }
+   }
+   RESTORE_STACK;
+   return frame_size;
+}
+
+#ifdef FIXED_POINT
+int opus_multistream_decode(
+      OpusMSDecoder *st,            /* Encoder state */
+      const unsigned char *data,
+      int len,
+      opus_int16 *pcm,
+      int frame_size,
+      int decode_fec
+)
+{
+   return opus_multistream_decode_native(st, data, len, pcm, frame_size, decode_fec);
+}
+
+#ifndef DISABLE_FLOAT_API
+int opus_multistream_decode_float(OpusMSDecoder *st, const unsigned char *data,
+      int len, float *pcm, int frame_size, int decode_fec)
+{
+   VARDECL(opus_int16, out);
+   int ret, i;
+   ALLOC_STACK;
+
+   ALLOC(out, frame_size*st->layout.nb_channels, opus_int16);
+
+   ret = opus_multistream_decode_native(st, data, len, out, frame_size, decode_fec);
+   if (ret > 0)
+   {
+      for (i=0;i<ret*st->layout.nb_channels;i++)
+         pcm[i] = (1./32768.)*(out[i]);
+   }
+   RESTORE_STACK;
+   return ret;
+}
+#endif
+
+#else
+
+int opus_multistream_decode(OpusMSDecoder *st, const unsigned char *data,
+      int len, opus_int16 *pcm, int frame_size, int decode_fec)
+{
+   VARDECL(float, out);
+   int ret, i;
+   ALLOC_STACK;
+
+   ALLOC(out, frame_size*st->layout.nb_channels, float);
+
+   ret = opus_multistream_decode_native(st, data, len, out, frame_size, decode_fec);
+   if (ret > 0)
+   {
+      for (i=0;i<ret*st->layout.nb_channels;i++)
+         pcm[i] = FLOAT2INT16(out[i]);
+   }
+   RESTORE_STACK;
+   return ret;
+}
+
+int opus_multistream_decode_float(
+      OpusMSDecoder *st,            /* Encoder state */
+      const unsigned char *data,
+      int len,
+      float *pcm,
+      int frame_size,
+      int decode_fec
+)
+{
+   return opus_multistream_decode_native(st, data, len, pcm, 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)
+   {
+       default:
+       {
+          int s;
+          /* This only works for int32* params, but that's all we have right now */
+          opus_uint32 *value = va_arg(ap, opus_uint32*);
+          for (s=0;s<st->layout.nb_streams;s++)
+          {
+             OpusDecoder *enc;
+
+             enc = (OpusDecoder*)ptr;
+             if (s < st->layout.nb_coupled_streams)
+                ptr += align(coupled_size);
+             else
+                ptr += align(mono_size);
+             ret = opus_decoder_ctl(enc, request, value);
+             if (ret < 0)
+                break;
+          }
+       }
+       break;
+   }
+
+   va_end(ap);
+   return ret;
+}
+
+
+void opus_multistream_decoder_destroy(OpusMSDecoder *st)
+{
+    free(st);
+}

src/opus_multistream.h

@@ -0,0 +1,121 @@
+/* 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 FOUNDATION 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.
+*/
+
+
+#ifndef OPUS_MULTISTREAM_H
+#define OPUS_MULTISTREAM_H
+
+#include "opus.h"
+
+typedef struct OpusMSEncoder OpusMSEncoder;
+typedef struct OpusMSDecoder OpusMSDecoder;
+
+OPUS_EXPORT OpusMSEncoder *opus_multistream_encoder_create(
+      int Fs,                     /* Sampling rate of input signal (Hz) */
+      int channels,               /* Number of channels (1/2) in input signal */
+      int streams,
+      int coupled_streams,
+      unsigned char *mapping,
+      int application             /* Coding mode (OPUS_APPLICATION_VOIP/OPUS_APPLICATION_AUDIO) */
+);
+
+OPUS_EXPORT int opus_multistream_encoder_init(
+      OpusMSEncoder *st,            /* Encoder state */
+      int Fs,                     /* Sampling rate of input signal (Hz) */
+      int channels,               /* Number of channels (1/2) in input signal */
+      int streams,
+      int coupled_streams,
+      unsigned char *mapping,
+      int application             /* Coding mode (OPUS_APPLICATION_VOIP/OPUS_APPLICATION_AUDIO) */
+);
+
+/* Returns length of the data payload (in bytes) */
+OPUS_EXPORT int opus_multistream_encode(
+    OpusMSEncoder *st,            /* Encoder state */
+    const opus_int16 *pcm,      /* Input signal (interleaved if 2 channels). length is frame_size*channels */
+    int frame_size,             /* Number of samples per frame of input signal */
+    unsigned char *data,        /* Output payload (no more than max_data_bytes long) */
+    int max_data_bytes          /* Allocated memory for payload; don't use for controlling bitrate */
+);
+
+/* Returns length of the data payload (in bytes) */
+OPUS_EXPORT int opus_multistream_encode_float(
+      OpusMSEncoder *st,            /* Encoder state */
+      const float *pcm,      /* Input signal (interleaved if 2 channels). length is frame_size*channels */
+      int frame_size,             /* Number of samples per frame of input signal */
+      unsigned char *data,        /* Output payload (no more than max_data_bytes long) */
+      int max_data_bytes          /* Allocated memory for payload; don't use for controlling bitrate */
+  );
+
+OPUS_EXPORT void opus_multistream_encoder_destroy(OpusMSEncoder *st);
+
+OPUS_EXPORT int opus_multistream_encoder_ctl(OpusMSEncoder *st, int request, ...);
+
+OPUS_EXPORT OpusMSDecoder *opus_multistream_decoder_create(
+      int Fs,                     /* Sampling rate of input signal (Hz) */
+      int channels,               /* Number of channels (1/2) in input signal */
+      int streams,
+      int coupled_streams,
+      unsigned char *mapping
+);
+
+OPUS_EXPORT int opus_multistream_decoder_init(
+      OpusMSDecoder *st,            /* Encoder state */
+      int Fs,                     /* Sampling rate of input signal (Hz) */
+      int channels,               /* Number of channels (1/2) in input signal */
+      int streams,
+      int coupled_streams,
+      unsigned char *mapping
+);
+
+/* Returns the number of samples decoded or a negative error code */
+OPUS_EXPORT int opus_multistream_decode(
+    OpusMSDecoder *st,            /* Decoder state */
+    const unsigned char *data,  /* Input payload. Use a NULL pointer to indicate packet loss */
+    int len,                    /* Number of bytes in payload */
+    opus_int16 *pcm,            /* Output signal (interleaved if 2 channels). length is frame_size*channels */
+    int frame_size,             /* Number of samples per frame of input signal */
+    int decode_fec              /* Flag (0/1) to request that any in-band forward error correction data be */
+                                /* decoded. If no such data is available the frame is decoded as if it were lost. */
+);
+
+/* Returns the number of samples decoded or a negative error code */
+OPUS_EXPORT int opus_multistream_decode_float(
+    OpusMSDecoder *st,            /* Decoder state */
+    const unsigned char *data,  /* Input payload. Use a NULL pointer to indicate packet loss */
+    int len,                    /* Number of bytes in payload */
+    float *pcm,                 /* Output signal (interleaved if 2 channels). length is frame_size*channels */
+    int frame_size,             /* Number of samples per frame of input signal */
+    int decode_fec              /* Flag (0/1) to request that any in-band forward error correction data be */
+                                /* decoded. If no such data is available the frame is decoded as if it were lost. */
+);
+
+OPUS_EXPORT int opus_multistream_decoder_ctl(OpusMSDecoder *st, int request, ...);
+
+OPUS_EXPORT void opus_multistream_decoder_destroy(OpusMSDecoder *st);
+
+#endif /* OPUS_MULTISTREAM_H */

src/opus_private.h

@@ -29,8 +29,14 @@
 #ifndef OPUS_PRIVATE_H
 #define OPUS_PRIVATE_H
 
+#include "arch.h"
+#include "opus.h"
+
 int encode_size(int size, unsigned char *data);
 
+int opus_decode_native(OpusDecoder *st, const unsigned char *data, int len,
+      opus_val16 *pcm, int frame_size, int decode_fec, int self_delimited, int *packet_offset);
+
 /* Make sure everything's aligned to 4 bytes (this may need to be increased
    on really weird architectures) */
 static inline int align(int i)