Restores larger output buffer size when output stream requiring smaller size is closed

media/audio/mac/audio_manager_mac.cc

 // 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.
 
 #include "media/audio/mac/audio_manager_mac.h"
 
-#include <stdint.h>
+#include <algorithm>
+#include <map>
+#include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/mac/mac_logging.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/macros.h"
 #include "base/memory/free_deleter.h"
 #include "base/power_monitor/power_monitor.h"
 #include "base/power_monitor/power_observer.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 458 matching lines @@
 }
 
 void AudioManagerMac::GetAudioOutputDeviceNames(
     media::AudioDeviceNames* device_names) {
   DCHECK(device_names->empty());
   GetAudioDeviceInfo(false, device_names);
 }
 
 AudioParameters AudioManagerMac::GetInputStreamParameters(
     const std::string& device_id) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   AudioDeviceID device = GetAudioDeviceIdByUId(true, device_id);
   if (device == kAudioObjectUnknown) {
     DLOG(ERROR) << "Invalid device " << device_id;
     return AudioParameters(
         AudioParameters::AUDIO_PCM_LOW_LATENCY, CHANNEL_LAYOUT_STEREO,
         kFallbackSampleRate, 16, ChooseBufferSize(true, kFallbackSampleRate));
   }
 
   int channels = 0;
   ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
@@ skipping 95 matching lines @@
     if (default_device == *iter)
       return *iter;
   }
 
   // Failed to figure out which is the matching device, return an empty string.
   return std::string();
 }
 
 AudioOutputStream* AudioManagerMac::MakeLinearOutputStream(
     const AudioParameters& params) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   return MakeLowLatencyOutputStream(params, std::string());
 }
 
 AudioOutputStream* AudioManagerMac::MakeLowLatencyOutputStream(
     const AudioParameters& params,
     const std::string& device_id) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   bool device_listener_first_init = false;
   // Lazily create the audio device listener on the first stream creation,
   // even if getting an audio device fails. Otherwise, if we have 0 audio
   // devices, the listener will never be initialized, and new valid devices
   // will never be detected.
   if (!output_device_listener_) {
     // NOTE: Use BindToCurrentLoop() to ensure the callback is always PostTask'd
     // even if OSX calls us on the right thread.  Some CoreAudio drivers will
     // fire the callbacks during stream creation, leading to re-entrancy issues
     // otherwise.  See http://crbug.com/349604
@@ skipping 48 matching lines @@
     return std::string();
 
   std::string ret(base::SysCFStringRefToUTF8(device_uid));
   CFRelease(device_uid);
 
   return ret;
 }
 
 AudioInputStream* AudioManagerMac::MakeLinearInputStream(
     const AudioParameters& params, const std::string& device_id) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LINEAR, params.format());
   AudioInputStream* stream = new PCMQueueInAudioInputStream(this, params);
   basic_input_streams_.push_back(stream);
   return stream;
 }
 
 AudioInputStream* AudioManagerMac::MakeLowLatencyInputStream(
     const AudioParameters& params, const std::string& device_id) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LOW_LATENCY, params.format());
   // Gets the AudioDeviceID that refers to the AudioInputDevice with the device
   // unique id. This AudioDeviceID is used to set the device for Audio Unit.
   AudioDeviceID audio_device_id = GetAudioDeviceIdByUId(true, device_id);
   AUAudioInputStream* stream = NULL;
   if (audio_device_id != kAudioObjectUnknown) {
     stream = new AUAudioInputStream(this, params, audio_device_id);
     low_latency_input_streams_.push_back(stream);
   }
 
   return stream;
 }
 
 AudioParameters AudioManagerMac::GetPreferredOutputStreamParameters(
     const std::string& output_device_id,
     const AudioParameters& input_params) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   const AudioDeviceID device = GetAudioDeviceIdByUId(false, output_device_id);
   if (device == kAudioObjectUnknown) {
     DLOG(ERROR) << "Invalid output device " << output_device_id;
     return input_params.IsValid() ? input_params : AudioParameters(
         AudioParameters::AUDIO_PCM_LOW_LATENCY, CHANNEL_LAYOUT_STEREO,
         kFallbackSampleRate, 16, ChooseBufferSize(false, kFallbackSampleRate));
   }
 
   const bool has_valid_input_params = input_params.IsValid();
   const int hardware_sample_rate = HardwareSampleRateForDevice(device);
@@ skipping 201 matching lines @@
       << "AudioUnitSetProperty(kAudioDevicePropertyBufferFrameSize) failed.  "
       << "Size:: " << buffer_size;
   *size_was_changed = (result == noErr);
   DVLOG_IF(1, result == noErr) << "IO buffer size changed to: " << buffer_size;
   // Store the currently used (after a change) I/O buffer frame size.
   *io_buffer_frame_size = buffer_size;
 
   return (result == noErr);
 }
 
+#if !defined(NDEBUG)
+void AudioManagerMac::PrintOutputBufferSizes() {
+  for (auto* stream : output_streams_) {
+    DVLOG(1) << "[id=0x" << std::hex << stream->device_id() << "] " << std::dec
+             << "requested: " << stream->requested_buffer_size() << ", "
+             << "actual: " << stream->actual_buffer_size();
+  }
+}
+#endif  // !defined(NDEBUG)
+
+bool AudioManagerMac::IncreaseIOBufferSizeIfPossible(AudioDeviceID device_id) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  DVLOG(1) << "IncreaseIOBufferSizeIfPossible(id=0x" << std::hex << device_id
+           << ")";
+
+  // Scan all active output streams using the specified |device_id|. Store the
+  // actual I/O buffer size once and add all requested buffer sizes to a list.
+  // In addition, build a list of output streams using |device_id|.

[o1ka, 2016/04/25 15:13:26]

It does not seem to be used - am I missing something?

[henrika (OOO until Aug 14), 2016/04/26 11:47:28]

I actually only use the first stream in the list. Will change data structure.

+  size_t actual_size = 0;
+  std::vector<size_t> requested_sizes;
+  std::list<AUHALStream*> output_streams;
+  for (auto* stream : output_streams_) {
+    if (stream->device_id() == device_id) {
+      if (actual_size == 0) {
+        // All active output streams uses the same actual I/O buffer size given
+        // a unique device ID. Hence, it is sufficient to store one value once.
+        actual_size = stream->actual_buffer_size();
+      }
+      requested_sizes.push_back(stream->requested_buffer_size());
+      output_streams.push_back(stream);
+    }
+  }
+
+  if (output_streams.empty()) {
+    DVLOG(1) << "No action since there is no active stream for given device id";
+    return false;
+  }
+
+  // Sort the list of requested buffer sizes (lowest value comes first).
+  std::sort(requested_sizes.begin(), requested_sizes.end());
+  // It is only possible to revert to a larger buffer size if the lowest
+  // requested is not in use. Example: if the actual I/O buffer size is 256 and
+  // at least one output stream has asked for 256 as its buffer size, we can't
+  // start using a larger I/O buffer size.
+  if (requested_sizes[0] == actual_size) {
+    DVLOG(1) << "No action since lowest possible size is already in use: "
+             << actual_size;
+    return false;
+  }
+
+  // Add a handy log message to track the current status before trying to make
+  // a change.
+  for (auto it = requested_sizes.begin(); it != requested_sizes.end(); ++it) {

[o1ka, 2016/04/25 15:13:26]

Do I understand it correctly that this information is important for diagnostics,
and otherwise we would just find out the minimum requested buffer size without
keeping a list and sorting it?
Can we probably just print this information at l.956 and keep there track of a
minimum requested size found so far, instead of keeping a vector? In the end it
looks like only the minimum value is used.

+    DVLOG(1) << "requested:" << *it << " actual: " << actual_size;
+  }
+
+  // It should now be safe to increase the I/O buffer size to a new (higher)
+  // value using the first value in |requested_sizes|. Doing so will save
+  // system resources. All active output streams with the same |device_id| are
+  // affected by this change but it is only required to apply the change to one
+  // of the streams. Currently the first stream in the list is utilized.
+  const size_t increased_io_buffer_frame_size = requested_sizes[0];
+  DVLOG(1) << "increased_io_buffer_frame_size: "
+           << increased_io_buffer_frame_size;
+  bool size_was_changed = false;
+  size_t io_buffer_frame_size = 0;
+  bool result = MaybeChangeBufferSize(
+      device_id, output_streams.front()->audio_unit(), 0,
+      increased_io_buffer_frame_size, &size_was_changed, &io_buffer_frame_size);
+  DCHECK_EQ(io_buffer_frame_size, increased_io_buffer_frame_size);
+
+  return result;
+}
+
+bool AudioManagerMac::AudioDeviceIsUsedForInput(AudioDeviceID device_id) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  if (!basic_input_streams_.empty()) {
+    // For Audio Queues and in the default case (Mac OS X), the audio comes
+    // from the system’s default audio input device as set by a user in System
+    // Preferences.
+    AudioDeviceID default_id;
+    GetDefaultDevice(&default_id, true);
+    if (default_id == device_id)
+      return true;
+  }
+
+  // Each low latency streams has its own device ID.
+  for (auto* stream : low_latency_input_streams_) {
+    if (stream->device_id() == device_id)
+      return true;
+  }
+  return false;
+}
+
 void AudioManagerMac::ReleaseOutputStream(AudioOutputStream* stream) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  const AudioDeviceID id = static_cast<AUHALStream*>(stream)->device_id();
+  DVLOG(1) << "Closing down output stream with id=0x" << std::hex << id;
+
+  // Start by closing down the specified output stream.
   output_streams_.remove(static_cast<AUHALStream*>(stream));
+#if !defined(NDEBUG)
+  PrintOutputBufferSizes();
+#endif  // !defined(NDEBUG)
   AudioManagerBase::ReleaseOutputStream(stream);
+
+  // Prevent attempt to alter buffer size if the released stream was the last
+  // output stream.
+  if (output_streams_.empty())
+    return;
+
+  if (!AudioDeviceIsUsedForInput(id)) {
+    // The current audio device is not used for input. See if it is possible to
+    // increase the IO buffer size (saves power) given the remaining output
+    // audio streams and their buffer size requirements.
+    IncreaseIOBufferSizeIfPossible(id);
+  }
 }
 
 void AudioManagerMac::ReleaseInputStream(AudioInputStream* stream) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   auto stream_it = std::find(basic_input_streams_.begin(),
                              basic_input_streams_.end(),
                              stream);
   if (stream_it == basic_input_streams_.end())
     low_latency_input_streams_.remove(static_cast<AUAudioInputStream*>(stream));
   else
     basic_input_streams_.erase(stream_it);
 
   AudioManagerBase::ReleaseInputStream(stream);
 }
 
 ScopedAudioManagerPtr CreateAudioManager(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
     AudioLogFactory* audio_log_factory) {
   return ScopedAudioManagerPtr(
       new AudioManagerMac(std::move(task_runner), std::move(worker_task_runner),
                           audio_log_factory));
 }
 
 }  // namespace media