Make OS audio buffer size limits visible.

media/audio/cras/audio_manager_cras.cc

 // Copyright 2013 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.
 
 #include "media/audio/cras/audio_manager_cras.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/nix/xdg_util.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/sys_info.h"
 #include "chromeos/audio/audio_device.h"
 #include "chromeos/audio/cras_audio_handler.h"
 #include "media/audio/audio_device_description.h"
 #include "media/audio/audio_features.h"
 #include "media/audio/cras/cras_input.h"
 #include "media/audio/cras/cras_unified.h"
 #include "media/base/channel_layout.h"
+#include "media/base/limits.h"
 #include "media/base/localized_strings.h"
 
 // cras_util.h headers pull in min/max macros...
 // TODO(dgreid): Fix headers such that these aren't imported.
 #undef min
 #undef max
 
 namespace media {
 namespace {
 
 // Maximum number of output streams that can be open simultaneously.
 const int kMaxOutputStreams = 50;
 
 // Default sample rate for input and output streams.
 const int kDefaultSampleRate = 48000;
 
-// Define bounds for the output buffer size.
-const int kMinimumOutputBufferSize = 512;
-const int kMaximumOutputBufferSize = 8192;
-
 // Default input buffer size.
 const int kDefaultInputBufferSize = 1024;
 
 const char kBeamformingOnDeviceId[] = "default-beamforming-on";
 const char kBeamformingOffDeviceId[] = "default-beamforming-off";
 
 const char kInternalInputVirtualDevice[] = "Built-in mic";
 const char kInternalOutputVirtualDevice[] = "Built-in speaker";
 const char kHeadphoneLineOutVirtualDevice[] = "Headphone/Line Out";
 
@@ skipping 244 matching lines @@
 }
 
 int AudioManagerCras::GetMinimumOutputBufferSizePerBoard() {
   // On faster boards we can use smaller buffer size for lower latency.
   // On slower boards we should use larger buffer size to prevent underrun.
   std::string board = base::SysInfo::GetLsbReleaseBoard();
   if (board == "kevin")
     return 768;
   else if (board == "samus")
     return 256;
-  return kMinimumOutputBufferSize;
+  return 512;
 }
 
 AudioParameters AudioManagerCras::GetPreferredOutputStreamParameters(
     const std::string& output_device_id,
     const AudioParameters& input_params) {
   ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   int sample_rate = kDefaultSampleRate;
   int buffer_size = GetMinimumOutputBufferSizePerBoard();
   int bits_per_sample = 16;
   if (input_params.IsValid()) {
     sample_rate = input_params.sample_rate();
     bits_per_sample = input_params.bits_per_sample();
     channel_layout = input_params.channel_layout();
     buffer_size =
-        std::min(kMaximumOutputBufferSize,
-                 std::max(buffer_size, input_params.frames_per_buffer()));
+        std::min(static_cast<int>(limits::kMaxAudioBufferSize),
+                 std::max(static_cast<int>(limits::kMinAudioBufferSize),
+                          input_params.frames_per_buffer()));
   }
 
   int user_buffer_size = GetUserBufferSize();
   if (user_buffer_size)
     buffer_size = user_buffer_size;
 
   return AudioParameters(AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout,
                          sample_rate, bits_per_sample, buffer_size);
 }
 
@@ skipping 25 matching lines @@
 
 bool AudioManagerCras::IsDefault(const std::string& device_id, bool is_input) {
   AudioDeviceNames device_names;
   GetAudioDeviceNamesImpl(is_input, &device_names);
   DCHECK(!device_names.empty());
   const AudioDeviceName& device_name = device_names.front();
   return device_name.unique_id == device_id;
 }
 
 }  // namespace media