Allow more than 2 input channels in AudioProcessing.

webrtc/modules/audio_processing/audio_buffer.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/modules/audio_processing/audio_buffer.h"
 
+#include <type_traits>
+
 #include "webrtc/common_audio/include/audio_util.h"
 #include "webrtc/common_audio/resampler/push_sinc_resampler.h"
 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
 #include "webrtc/common_audio/channel_buffer.h"
 #include "webrtc/modules/audio_processing/common.h"
 
 namespace webrtc {
 namespace {
 
 const int kSamplesPer16kHzChannel = 160;
 const int kSamplesPer32kHzChannel = 320;
 const int kSamplesPer48kHzChannel = 480;
 
-bool HasKeyboardChannel(AudioProcessing::ChannelLayout layout) {
-  switch (layout) {
-    case AudioProcessing::kMono:
-    case AudioProcessing::kStereo:
-      return false;
-    case AudioProcessing::kMonoAndKeyboard:
-    case AudioProcessing::kStereoAndKeyboard:
-      return true;
-  }
-  assert(false);
-  return false;
-}
-
-int KeyboardChannelIndex(AudioProcessing::ChannelLayout layout) {
-  switch (layout) {
-    case AudioProcessing::kMono:
-    case AudioProcessing::kStereo:
-      assert(false);
-      return -1;
-    case AudioProcessing::kMonoAndKeyboard:
+int KeyboardChannelIndex(const StreamConfig& stream_config) {
+  switch (stream_config.num_channels()) {
+    case 1:
       return 1;
-    case AudioProcessing::kStereoAndKeyboard:
+    case 2:
       return 2;
   }
   assert(false);
   return -1;
 }
 
 template <typename T>
-void StereoToMono(const T* left, const T* right, T* out,
-                  int num_frames) {
-  for (int i = 0; i < num_frames; ++i)
-    out[i] = (left[i] + right[i]) / 2;
+void DownmixInterleavedToMono(const T* interleaved,
+                              T* deinterleaved,
+                              int num_multichannel_frames,
+                              int num_channels) {
+  return DownmixInterleavedToMonoImpl<T, T>(
+      interleaved, deinterleaved, num_multichannel_frames, num_channels);
+}
+
+template <>
+void DownmixInterleavedToMono<int16_t>(const int16_t* interleaved,
+                                       int16_t* deinterleaved,
+                                       int num_multichannel_frames,
+                                       int num_channels) {
+  return DownmixInterleavedToMonoImpl<int16_t, int32_t>(
+      interleaved, deinterleaved, num_multichannel_frames, num_channels);
 }
 
 int NumBandsFromSamplesPerChannel(int num_frames) {
   int num_bands = 1;
   if (num_frames == kSamplesPer32kHzChannel ||
       num_frames == kSamplesPer48kHzChannel) {
     num_bands = rtc::CheckedDivExact(num_frames,
                                      static_cast<int>(kSamplesPer16kHzChannel));
   }
   return num_bands;
@@ skipping 15 matching lines @@
     num_bands_(NumBandsFromSamplesPerChannel(proc_num_frames_)),
     num_split_frames_(rtc::CheckedDivExact(proc_num_frames_, num_bands_)),
     mixed_low_pass_valid_(false),
     reference_copied_(false),
     activity_(AudioFrame::kVadUnknown),
     keyboard_data_(NULL),
     data_(new IFChannelBuffer(proc_num_frames_, num_proc_channels_)) {
   assert(input_num_frames_ > 0);
   assert(proc_num_frames_ > 0);
   assert(output_num_frames_ > 0);
-  assert(num_input_channels_ > 0 && num_input_channels_ <= 2);
+  assert(num_input_channels_ > 0);
   assert(num_proc_channels_ > 0 && num_proc_channels_ <= num_input_channels_);
 
   if (input_num_frames_ != proc_num_frames_ ||
       output_num_frames_ != proc_num_frames_) {
     // Create an intermediate buffer for resampling.
     process_buffer_.reset(new ChannelBuffer<float>(proc_num_frames_,
                                                    num_proc_channels_));
 
     if (input_num_frames_ != proc_num_frames_) {
       for (int i = 0; i < num_proc_channels_; ++i) {
@@ skipping 18 matching lines @@
                                           num_bands_));
     splitting_filter_.reset(new SplittingFilter(num_proc_channels_,
                                                 num_bands_,
                                                 proc_num_frames_));
   }
 }
 
 AudioBuffer::~AudioBuffer() {}
 
 void AudioBuffer::CopyFrom(const float* const* data,
-                           int num_frames,
-                           AudioProcessing::ChannelLayout layout) {
-  assert(num_frames == input_num_frames_);
-  assert(ChannelsFromLayout(layout) == num_input_channels_);
+                           const StreamConfig& stream_config) {
+  assert(stream_config.samples_per_channel() == input_num_frames_);
+  assert(stream_config.num_channels() == num_input_channels_);
   InitForNewData();
   // Initialized lazily because there's a different condition in
   // DeinterleaveFrom.
-  if ((num_input_channels_ == 2 && num_proc_channels_ == 1) && !input_buffer_) {
+  const bool need_to_downmix =
+      num_input_channels_ > 1 && num_proc_channels_ == 1;
+  if (need_to_downmix && !input_buffer_) {
     input_buffer_.reset(
         new IFChannelBuffer(input_num_frames_, num_proc_channels_));
   }
 
-  if (HasKeyboardChannel(layout)) {
-    keyboard_data_ = data[KeyboardChannelIndex(layout)];
+  if (stream_config.has_keyboard()) {
+    keyboard_data_ = data[KeyboardChannelIndex(stream_config)];
   }
 
   // Downmix.
   const float* const* data_ptr = data;
-  if (num_input_channels_ == 2 && num_proc_channels_ == 1) {
-    StereoToMono(data[0],
-                 data[1],
-                 input_buffer_->fbuf()->channels()[0],
-                 input_num_frames_);
+  if (need_to_downmix) {
+    DownmixToMono<float, float>(input_num_frames_,
+                                input_buffer_->fbuf()->channels()[0], data,
+                                num_input_channels_);
     data_ptr = input_buffer_->fbuf_const()->channels();
   }
 
   // Resample.
   if (input_num_frames_ != proc_num_frames_) {
     for (int i = 0; i < num_proc_channels_; ++i) {
       input_resamplers_[i]->Resample(data_ptr[i],
                                      input_num_frames_,
                                      process_buffer_->channels()[i],
                                      proc_num_frames_);
     }
     data_ptr = process_buffer_->channels();
   }
 
   // Convert to the S16 range.
   for (int i = 0; i < num_proc_channels_; ++i) {
     FloatToFloatS16(data_ptr[i],
                     proc_num_frames_,
                     data_->fbuf()->channels()[i]);
   }
 }
 
-void AudioBuffer::CopyTo(int num_frames,
-                         AudioProcessing::ChannelLayout layout,
+void AudioBuffer::CopyTo(const StreamConfig& stream_config,
                          float* const* data) {
-  assert(num_frames == output_num_frames_);
-  assert(ChannelsFromLayout(layout) == num_channels_);
+  assert(stream_config.samples_per_channel() == output_num_frames_);
+  assert(stream_config.num_channels() == num_channels_);
 
   // Convert to the float range.
   float* const* data_ptr = data;
   if (output_num_frames_ != proc_num_frames_) {
     // Convert to an intermediate buffer for subsequent resampling.
     data_ptr = process_buffer_->channels();
   }
   for (int i = 0; i < num_channels_; ++i) {
     FloatS16ToFloat(data_->fbuf()->channels()[i],
                     proc_num_frames_,
@@ skipping 139 matching lines @@
 
   if (num_proc_channels_ == 1) {
     return split_bands_const(0)[kBand0To8kHz];
   }
 
   if (!mixed_low_pass_valid_) {
     if (!mixed_low_pass_channels_.get()) {
       mixed_low_pass_channels_.reset(
           new ChannelBuffer<int16_t>(num_split_frames_, 1));
     }
-    StereoToMono(split_bands_const(0)[kBand0To8kHz],
-                 split_bands_const(1)[kBand0To8kHz],
-                 mixed_low_pass_channels_->channels()[0],
-                 num_split_frames_);
+    DownmixStereoToMono<int16_t, int32_t>(
+        num_split_frames_, mixed_low_pass_channels_->channels()[0],
+        split_bands_const(0)[kBand0To8kHz], split_bands_const(1)[kBand0To8kHz]);
     mixed_low_pass_valid_ = true;
   }
   return mixed_low_pass_channels_->channels()[0];
 }
 
 const int16_t* AudioBuffer::low_pass_reference(int channel) const {
   if (!reference_copied_) {
     return NULL;
   }
 
@@ skipping 48 matching lines @@
         new IFChannelBuffer(input_num_frames_, num_proc_channels_));
   }
   activity_ = frame->vad_activity_;
 
   int16_t* const* deinterleaved;
   if (input_num_frames_ == proc_num_frames_) {
     deinterleaved = data_->ibuf()->channels();
   } else {
     deinterleaved = input_buffer_->ibuf()->channels();
   }
-  if (num_input_channels_ == 2 && num_proc_channels_ == 1) {
-    // Downmix directly; no explicit deinterleaving needed.
-    for (int i = 0; i < input_num_frames_; ++i) {
-      deinterleaved[0][i] = (frame->data_[i * 2] + frame->data_[i * 2 + 1]) / 2;
-    }
+  if (num_proc_channels_ == 1) {
+    // Downmix and deinterleave simultaneously.
+    DownmixInterleavedToMono(frame->data_, deinterleaved[0], input_num_frames_,

[mgraczyk, 2015/07/10 00:33:36]

This function works for any number of input channels.

+                             num_input_channels_);
   } else {
     assert(num_proc_channels_ == num_input_channels_);
     Deinterleave(frame->data_,
                  input_num_frames_,
                  num_proc_channels_,
                  deinterleaved);
   }
 
   // Resample.
   if (input_num_frames_ != proc_num_frames_) {
@@ skipping 41 matching lines @@
 
 void AudioBuffer::SplitIntoFrequencyBands() {
   splitting_filter_->Analysis(data_.get(), split_data_.get());
 }
 
 void AudioBuffer::MergeFrequencyBands() {
   splitting_filter_->Synthesis(split_data_.get(), data_.get());
 }
 
 }  // namespace webrtc