Add a virtual beamforming audio device on ChromeOS.

media/audio/audio_parameters.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_AUDIO_AUDIO_PARAMETERS_H_
 #define MEDIA_AUDIO_AUDIO_PARAMETERS_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/time/time.h"
+#include "media/audio/point.h"
 #include "media/base/channel_layout.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 struct MEDIA_EXPORT AudioInputBufferParameters {
   double volume;
   uint32 size;
   bool key_pressed;
 };
@@ skipping 28 matching lines @@
   // effects should be enabled.
   enum PlatformEffectsMask {
     NO_EFFECTS = 0x0,
     ECHO_CANCELLER = 0x1,
     DUCKING = 0x2,  // Enables ducking if the OS supports it.
     KEYBOARD_MIC = 0x4,
     HOTWORD = 0x8,
   };
 
   AudioParameters();
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  int sample_rate, int bits_per_sample,
-                  int frames_per_buffer);
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  int sample_rate, int bits_per_sample,
-                  int frames_per_buffer, int effects);
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  int channels, int sample_rate, int bits_per_sample,
-                  int frames_per_buffer, int effects);
+  AudioParameters(
+      Format format,
+      ChannelLayout channel_layout,
+      int sample_rate,
+      int bits_per_sample,
+      int frames_per_buffer,
+      const std::vector<Point>& mic_positions = std::vector<Point>(),
+      int effects = NO_EFFECTS);
+  AudioParameters(
+      Format format,
+      int channels,
+      ChannelLayout channel_layout,
+      int sample_rate,
+      int bits_per_sample,
+      int frames_per_buffer,
+      const std::vector<Point>& mic_positions = std::vector<Point>(),
+      int effects = NO_EFFECTS);
+
+  ~AudioParameters();
 
   void Reset(Format format, ChannelLayout channel_layout,
              int channels, int sample_rate, int bits_per_sample,
              int frames_per_buffer);
 
   // Checks that all values are in the expected range. All limits are specified
   // in media::Limits.
   bool IsValid() const;
 
   // Returns a human-readable string describing |*this|.  For debugging & test
@@ skipping 16 matching lines @@
   // Comparison with other AudioParams.
   bool Equals(const AudioParameters& other) const;
 
   Format format() const { return format_; }
   ChannelLayout channel_layout() const { return channel_layout_; }
   int sample_rate() const { return sample_rate_; }
   int bits_per_sample() const { return bits_per_sample_; }
   int frames_per_buffer() const { return frames_per_buffer_; }
   int channels() const { return channels_; }
   int effects() const { return effects_; }
+  const std::vector<Point>& mic_positions() const { return mic_positions_; }
 
  private:
   // These members are mutable to support entire struct assignment. They should
   // not be mutated individually.
   Format format_;                 // Format of the stream.
   ChannelLayout channel_layout_;  // Order of surround sound channels.
   int sample_rate_;               // Sampling frequency/rate.
   int bits_per_sample_;           // Number of bits per sample.
   int frames_per_buffer_;         // Number of frames in a buffer.
 
   int channels_;                  // Number of channels. Value set based on
                                   // |channel_layout|.
+
+  // Microphone positions using Cartesian coordinates:
+  // x: the horizontal dimension, with positive to the right from the camera's
+  //    perspective.
+  // y: the depth dimension, with positive forward from the camera's
+  //    perspective.
+  // z: the vertical dimension, with positive upwards.
+  //
+  // Usually, the center of the microphone array will be treated as the origin
+  // (often the position of the camera).
+  //
+  // An empty vector indicates unknown positions.
+  std::vector<Point> mic_positions_;

[mcasas, 2015/09/02 03:05:37]

const?

[ajm, 2015/09/02 06:41:48]

The members aren't const to allow copy assignment and Reset(). That's hinted at
on l.119.

+
   int effects_;                   // Bitmask using PlatformEffectsMask.

[mcasas, 2015/09/02 03:05:37]

const?
And perhaps l.121-l.127 as well? 
Is strange that |mic_positions_| and |effects_| are not cleared
by Reset().

[mcasas, 2015/09/02 03:05:37]

const?
And perhaps l.121-l.127 as well? 
Is strange that |mic_positions_| and |effects_| are not cleared
by Reset().

[ajm, 2015/09/02 06:41:48]

As above.
I didn't change it because Reset() has no need to alter effects_ and
mic_positions_ in all uses. I agree resetting all members would be less
surprising though. Done.

 };
 
 // Comparison is useful when AudioParameters is used with std structures.
 inline bool operator<(const AudioParameters& a, const AudioParameters& b) {
   if (a.format() != b.format())
     return a.format() < b.format();
   if (a.channels() != b.channels())
     return a.channels() < b.channels();
   if (a.sample_rate() != b.sample_rate())
     return a.sample_rate() < b.sample_rate();
   if (a.bits_per_sample() != b.bits_per_sample())
     return a.bits_per_sample() < b.bits_per_sample();
   return a.frames_per_buffer() < b.frames_per_buffer();
 }
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_PARAMETERS_H_