Adds support for OpenSL ES based audio capture on Android

webrtc/modules/audio_device/android/opensles_common.cc

 /*
  *  Copyright (c) 2013 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_device/android/opensles_common.h"
 
-#include <assert.h>
 #include <SLES/OpenSLES.h>
 
 #include "webrtc/base/arraysize.h"
-#include "webrtc/modules/audio_device/android/audio_common.h"
-
-using webrtc::kNumChannels;
+#include "webrtc/base/checks.h"
 
 namespace webrtc {
 
 // Returns a string representation given an integer SL_RESULT_XXX code.
 // The mapping can be found in <SLES/OpenSLES.h>.
 const char* GetSLErrorString(size_t code) {
   static const char* sl_error_strings[] = {
       "SL_RESULT_SUCCESS",                 // 0
       "SL_RESULT_PRECONDITIONS_VIOLATED",  // 1
       "SL_RESULT_PARAMETER_INVALID",       // 2
@@ skipping 12 matching lines @@
       "SL_RESULT_OPERATION_ABORTED",       // 15
       "SL_RESULT_CONTROL_LOST",            // 16
   };
 
   if (code >= arraysize(sl_error_strings)) {
     return "SL_RESULT_UNKNOWN_ERROR";
   }
   return sl_error_strings[code];
 }
 
-SLDataFormat_PCM CreatePcmConfiguration(int sample_rate) {
-  SLDataFormat_PCM configuration;
-  configuration.formatType = SL_DATAFORMAT_PCM;
-  configuration.numChannels = kNumChannels;
-  // According to the opensles documentation in the ndk:
-  // samplesPerSec is actually in units of milliHz, despite the misleading name.
-  // It further recommends using constants. However, this would lead to a lot
-  // of boilerplate code so it is not done here.
-  configuration.samplesPerSec = sample_rate * 1000;
-  configuration.bitsPerSample = SL_PCMSAMPLEFORMAT_FIXED_16;
-  configuration.containerSize = SL_PCMSAMPLEFORMAT_FIXED_16;
-  configuration.channelMask = SL_SPEAKER_FRONT_CENTER;
-  if (2 == configuration.numChannels) {
-    configuration.channelMask =
-        SL_SPEAKER_FRONT_LEFT | SL_SPEAKER_FRONT_RIGHT;
+SLDataFormat_PCM CreatePCMConfiguration(size_t channels,
+                                        int sample_rate,
+                                        size_t bits_per_sample) {
+  RTC_CHECK_EQ(bits_per_sample, SL_PCMSAMPLEFORMAT_FIXED_16);
+  SLDataFormat_PCM format;
+  format.formatType = SL_DATAFORMAT_PCM;
+  format.numChannels = static_cast<SLuint32>(channels);
+  // Note that, the unit of sample rate is actually in milliHertz and not Hertz.
+  switch (sample_rate) {
+    case 8000:
+      format.samplesPerSec = SL_SAMPLINGRATE_8;
+      break;
+    case 16000:
+      format.samplesPerSec = SL_SAMPLINGRATE_16;
+      break;
+    case 22050:
+      format.samplesPerSec = SL_SAMPLINGRATE_22_05;
+      break;
+    case 32000:
+      format.samplesPerSec = SL_SAMPLINGRATE_32;
+      break;
+    case 44100:
+      format.samplesPerSec = SL_SAMPLINGRATE_44_1;
+      break;
+    case 48000:
+      format.samplesPerSec = SL_SAMPLINGRATE_48;
+      break;
+    default:

[tommi, 2016/09/15 09:34:13]

I think I've read somewhere that 96kHz is supported (possibly 88.2kHz then as
well?).

Do we have any stats from the field that give us confidence that we will never
see higher than 48kHz in should-be-supported situations?

[henrika_webrtc, 2016/09/16 13:30:47]

Great feedback. You are correct. I have never seen such a device but I am adding
it just in case.

+      RTC_CHECK(false) << "Unsupported sample rate: " << sample_rate;

[tommi, 2016/09/15 09:34:12]

nit: also include a break; here for consistency.

[henrika_webrtc, 2016/09/16 13:30:47]

Done.

   }
-  configuration.endianness = SL_BYTEORDER_LITTLEENDIAN;
-  return configuration;
+  format.bitsPerSample = SL_PCMSAMPLEFORMAT_FIXED_16;
+  format.containerSize = SL_PCMSAMPLEFORMAT_FIXED_16;
+  format.endianness = SL_BYTEORDER_LITTLEENDIAN;
+  if (format.numChannels == 1)

[tommi, 2016/09/15 09:34:13]

{}
(see lines below)

[henrika_webrtc, 2016/09/16 13:30:47]

Done.

+    format.channelMask = SL_SPEAKER_FRONT_CENTER;
+  else if (format.numChannels == 2)
+    format.channelMask = SL_SPEAKER_FRONT_LEFT | SL_SPEAKER_FRONT_RIGHT;
+  else
+    RTC_CHECK(false) << "Unsupported number of channels: "
+                     << format.numChannels;
+  return format;
 }
 
-}  // namespace webrtc_opensl
+}  // namespace webrtc