[opus] [PATCH] Add Functions to Create Ambisonic Multistream Encoder
Michael Graczyk
mgraczyk at google.com
Fri May 6 23:46:05 UTC 2016
Here is the modified patch. I added a flag to configure.ac which is set to
0 to disable ambisonics, and 1 to enable it. Right now the implementation
simply creates a surround encoder with N uncoupled streams.
Thanks,
Michael Graczyk
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From b6ef739067f5bfcdae61938ac0b34764e05e518e Mon Sep 17 00:00:00 2001
From: Michael Graczyk <michael at mgraczyk.com>
Date: Mon, 2 May 2016 21:42:18 -0700
Subject: [PATCH] Add experimental support for ambisonic encoding
The implementation currently uses the surround encoder with mapping family 255.
---
configure.ac | 11 +++++++++++
src/opus_multistream_encoder.c | 43 ++++++++++++++++++++++++++----------------
2 files changed, 38 insertions(+), 16 deletions(-)
diff --git a/configure.ac b/configure.ac
index a67aa37..b6ca573 100644
--- a/configure.ac
+++ b/configure.ac
@@ -736,6 +736,16 @@ AS_IF([test "$enable_fuzzing" = "yes"], [
AC_DEFINE([FUZZING], [1], [Fuzzing])
])
+AC_ARG_ENABLE([ambisonics],
+ [AS_HELP_STRING([--enable-ambisonics],[enable experimental ambisonic encoding and decoding support])],,
+ [enable_ambisonics=no])
+
+AS_IF([test "$enable_ambisonics" = "yes"], [
+ AC_DEFINE([ENABLE_EXPERIMENTAL_AMBISONICS], [1], [Ambisonics Support])
+], [
+ AC_DEFINE([ENABLE_EXPERIMENTAL_AMBISONICS], [0], [Ambisonics Support])
+])
+
AC_ARG_ENABLE([doc],
[AS_HELP_STRING([--disable-doc], [Do not build API documentation])],,
[enable_doc=yes])
@@ -820,6 +830,7 @@ AC_MSG_NOTICE([
Custom modes: .................. ${enable_custom_modes}
Assertion checking: ............ ${enable_assertions}
Fuzzing: ....................... ${enable_fuzzing}
+ Ambisonics support: .............${enable_ambisonics}
API documentation: ............. ${enable_doc}
Extra programs: ................ ${enable_extra_programs}
diff --git a/src/opus_multistream_encoder.c b/src/opus_multistream_encoder.c
index 9e85773..f0f344b 100644
--- a/src/opus_multistream_encoder.c
+++ b/src/opus_multistream_encoder.c
@@ -70,13 +70,19 @@ typedef void (*opus_copy_channel_in_func)(
int frame_size
);
+typedef enum {
+ ALLOCATION_MODE_NONE = 0,
+ ALLOCATION_MODE_SURROUND = 1,
+ ALLOCATION_MODE_AMBISONICS = 2,
+} AllocationMode;
+
struct OpusMSEncoder {
ChannelLayout layout;
int arch;
int lfe_stream;
int application;
int variable_duration;
- int surround;
+ AllocationMode allocation_mode;
opus_int32 bitrate_bps;
float subframe_mem[3];
/* Encoder states go here */
@@ -242,6 +248,7 @@ void surround_analysis(const CELTMode *celt_mode, const void *pcm, opus_val16 *b
upsample = resampling_factor(rate);
frame_size = len*upsample;
+ /* LM = log2(frame_size / 120) */
for (LM=0;LM<celt_mode->maxLM;LM++)
if (celt_mode->shortMdctSize<<LM==frame_size)
break;
@@ -394,7 +401,8 @@ opus_int32 opus_multistream_surround_encoder_get_size(int channels, int mapping_
{
nb_streams=vorbis_mappings[channels-1].nb_streams;
nb_coupled_streams=vorbis_mappings[channels-1].nb_coupled_streams;
- } else if (mapping_family==255)
+ } else if (mapping_family==255
+ || (mapping_family==2 && ENABLE_EXPERIMENTAL_AMBISONICS))
{
nb_streams=channels;
nb_coupled_streams=0;
@@ -408,7 +416,6 @@ opus_int32 opus_multistream_surround_encoder_get_size(int channels, int mapping_
return size;
}
-
static int opus_multistream_encoder_init_impl(
OpusMSEncoder *st,
opus_int32 Fs,
@@ -417,7 +424,7 @@ static int opus_multistream_encoder_init_impl(
int coupled_streams,
const unsigned char *mapping,
int application,
- int surround
+ AllocationMode allocation_mode
)
{
int coupled_size;
@@ -434,7 +441,7 @@ 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;
- if (!surround)
+ if (allocation_mode != ALLOCATION_MODE_SURROUND)
st->lfe_stream = -1;
st->bitrate_bps = OPUS_AUTO;
st->application = application;
@@ -463,12 +470,12 @@ static int opus_multistream_encoder_init_impl(
if(ret!=OPUS_OK)return ret;
ptr += align(mono_size);
}
- if (surround)
+ if (allocation_mode == ALLOCATION_MODE_SURROUND)
{
OPUS_CLEAR(ms_get_preemph_mem(st), channels);
OPUS_CLEAR(ms_get_window_mem(st), channels*120);
}
- st->surround = surround;
+ st->allocation_mode = allocation_mode;
return OPUS_OK;
}
@@ -482,7 +489,9 @@ int opus_multistream_encoder_init(
int application
)
{
- return opus_multistream_encoder_init_impl(st, Fs, channels, streams, coupled_streams, mapping, application, 0);
+ return opus_multistream_encoder_init_impl(st, Fs, channels, streams,
+ coupled_streams, mapping,
+ application, ALLOCATION_MODE_NONE);
}
int opus_multistream_surround_encoder_init(
@@ -523,7 +532,8 @@ int opus_multistream_surround_encoder_init(
mapping[i] = vorbis_mappings[channels-1].mapping[i];
if (channels>=6)
st->lfe_stream = *streams-1;
- } else if (mapping_family==255)
+ } else if (mapping_family==255
+ || (mapping_family==2 && ENABLE_EXPERIMENTAL_AMBISONICS))
{
int i;
*streams=channels;
@@ -532,6 +542,7 @@ int opus_multistream_surround_encoder_init(
mapping[i] = i;
} else
return OPUS_UNIMPLEMENTED;
+
return opus_multistream_encoder_init_impl(st, Fs, channels, *streams, *coupled_streams,
mapping, application, channels>2&&mapping_family==1);
}
@@ -730,7 +741,7 @@ static int opus_multistream_encode_native
opus_int32 smallest_packet;
ALLOC_STACK;
- if (st->surround)
+ if (st->allocation_mode == ALLOCATION_MODE_SURROUND)
{
preemph_mem = ms_get_preemph_mem(st);
mem = ms_get_window_mem(st);
@@ -784,7 +795,7 @@ static int opus_multistream_encode_native
mono_size = opus_encoder_get_size(1);
ALLOC(bandSMR, 21*st->layout.nb_channels, opus_val16);
- if (st->surround)
+ if (st->allocation_mode == ALLOCATION_MODE_SURROUND)
{
surround_analysis(celt_mode, pcm, bandSMR, mem, preemph_mem, frame_size, 120, st->layout.nb_channels, Fs, copy_channel_in, st->arch);
}
@@ -813,7 +824,7 @@ static int opus_multistream_encode_native
else
ptr += align(mono_size);
opus_encoder_ctl(enc, OPUS_SET_BITRATE(bitrates[s]));
- if (st->surround)
+ if (st->allocation_mode == ALLOCATION_MODE_SURROUND)
{
opus_int32 equiv_rate;
equiv_rate = st->bitrate_bps;
@@ -859,7 +870,7 @@ static int opus_multistream_encode_native
(*copy_channel_in)(buf+1, 2,
pcm, st->layout.nb_channels, right, frame_size);
ptr += align(coupled_size);
- if (st->surround)
+ if (st->allocation_mode == ALLOCATION_MODE_SURROUND)
{
for (i=0;i<21;i++)
{
@@ -875,7 +886,7 @@ static int opus_multistream_encode_native
(*copy_channel_in)(buf, 1,
pcm, st->layout.nb_channels, chan, frame_size);
ptr += align(mono_size);
- if (st->surround)
+ if (st->allocation_mode == ALLOCATION_MODE_SURROUND)
{
for (i=0;i<21;i++)
bandLogE[i] = bandSMR[21*chan+i];
@@ -883,7 +894,7 @@ static int opus_multistream_encode_native
c1 = chan;
c2 = -1;
}
- if (st->surround)
+ if (st->allocation_mode == ALLOCATION_MODE_SURROUND)
opus_encoder_ctl(enc, OPUS_SET_ENERGY_MASK(bandLogE));
/* number of bytes left (+Toc) */
curr_max = max_data_bytes - tot_size;
@@ -1183,7 +1194,7 @@ int opus_multistream_encoder_ctl(OpusMSEncoder *st, int request, ...)
{
int s;
st->subframe_mem[0] = st->subframe_mem[1] = st->subframe_mem[2] = 0;
- if (st->surround)
+ if (st->allocation_mode == ALLOCATION_MODE_SURROUND)
{
OPUS_CLEAR(ms_get_preemph_mem(st), st->layout.nb_channels);
OPUS_CLEAR(ms_get_window_mem(st), st->layout.nb_channels*120);
--
2.8.0.rc3.226.g39d4020
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