media/audio/pulse/pulse_util.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/pulse/pulse_util.h"

#include <stdint.h>
#include <string.h>

#include <memory>

#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "media/audio/audio_device_description.h"
#include "media/base/audio_timestamp_helper.h"

#if defined(DLOPEN_PULSEAUDIO)
#include "media/audio/pulse/pulse_stubs.h"

using media_audio_pulse::kModulePulse;
using media_audio_pulse::InitializeStubs;
using media_audio_pulse::StubPathMap;
#endif  // defined(DLOPEN_PULSEAUDIO)

namespace media {

namespace pulse {

namespace {

#if defined(GOOGLE_CHROME_BUILD)
static const char kBrowserDisplayName[] = "google-chrome";
#else
static const char kBrowserDisplayName[] = "chromium-browser";
#endif

#if defined(DLOPEN_PULSEAUDIO)
static const base::FilePath::CharType kPulseLib[] =
    FILE_PATH_LITERAL("libpulse.so.0");
#endif

void DestroyMainloop(pa_threaded_mainloop* mainloop) {
  pa_threaded_mainloop_stop(mainloop);
  pa_threaded_mainloop_free(mainloop);
}

void DestroyContext(pa_context* context) {
  pa_context_set_state_callback(context, NULL, NULL);
  pa_context_disconnect(context);
  pa_context_unref(context);
}

pa_channel_position ChromiumToPAChannelPosition(Channels channel) {
  switch (channel) {
    // PulseAudio does not differentiate between left/right and
    // stereo-left/stereo-right, both translate to front-left/front-right.
    case LEFT:
      return PA_CHANNEL_POSITION_FRONT_LEFT;
    case RIGHT:
      return PA_CHANNEL_POSITION_FRONT_RIGHT;
    case CENTER:
      return PA_CHANNEL_POSITION_FRONT_CENTER;
    case LFE:
      return PA_CHANNEL_POSITION_LFE;
    case BACK_LEFT:
      return PA_CHANNEL_POSITION_REAR_LEFT;
    case BACK_RIGHT:
      return PA_CHANNEL_POSITION_REAR_RIGHT;
    case LEFT_OF_CENTER:
      return PA_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER;
    case RIGHT_OF_CENTER:
      return PA_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER;
    case BACK_CENTER:
      return PA_CHANNEL_POSITION_REAR_CENTER;
    case SIDE_LEFT:
      return PA_CHANNEL_POSITION_SIDE_LEFT;
    case SIDE_RIGHT:
      return PA_CHANNEL_POSITION_SIDE_RIGHT;
    default:
      NOTREACHED() << "Invalid channel: " << channel;
      return PA_CHANNEL_POSITION_INVALID;
  }
}

class ScopedPropertyList {
 public:
  ScopedPropertyList() : property_list_(pa_proplist_new()) {}
  ~ScopedPropertyList() { pa_proplist_free(property_list_); }

  pa_proplist* get() const { return property_list_; }

 private:
  pa_proplist* property_list_;
  DISALLOW_COPY_AND_ASSIGN(ScopedPropertyList);
};

struct InputBusData {
  InputBusData(pa_threaded_mainloop* loop, const std::string& name)
      : loop_(loop), name_(name), bus_() {}

  pa_threaded_mainloop* const loop_;
  const std::string& name_;
  std::string bus_;
};

struct OutputBusData {
  OutputBusData(pa_threaded_mainloop* loop, const std::string& bus)
      : loop_(loop), name_(), bus_(bus) {}

  pa_threaded_mainloop* const loop_;
  std::string name_;
  const std::string& bus_;
};

void InputBusCallback(pa_context* context,
                      const pa_source_info* info,
                      int error,
                      void* user_data) {
  InputBusData* data = static_cast<InputBusData*>(user_data);

  if (error) {
    // We have checked all the devices now.
    pa_threaded_mainloop_signal(data->loop_, 0);
    return;
  }

  if (strcmp(info->name, data->name_.c_str()) == 0 &&
      pa_proplist_contains(info->proplist, PA_PROP_DEVICE_BUS)) {
    data->bus_ = pa_proplist_gets(info->proplist, PA_PROP_DEVICE_BUS);
  }
}

void OutputBusCallback(pa_context* context,
                       const pa_sink_info* info,
                       int error,
                       void* user_data) {
  OutputBusData* data = static_cast<OutputBusData*>(user_data);

  if (error) {
    // We have checked all the devices now.
    pa_threaded_mainloop_signal(data->loop_, 0);
    return;
  }

  if (pa_proplist_contains(info->proplist, PA_PROP_DEVICE_BUS) &&
      strcmp(pa_proplist_gets(info->proplist, PA_PROP_DEVICE_BUS),
             data->bus_.c_str()) == 0) {
    data->name_ = info->name;
  }
}

struct DefaultDevicesData {
  explicit DefaultDevicesData(pa_threaded_mainloop* loop) : loop_(loop) {}
  std::string input_;
  std::string output_;
  pa_threaded_mainloop* const loop_;
};

void GetDefaultDeviceIdCallback(pa_context* c,
                                const pa_server_info* info,
                                void* userdata) {
  DefaultDevicesData* data = static_cast<DefaultDevicesData*>(userdata);
  data->input_ = info->default_source_name;
  data->output_ = info->default_sink_name;
  pa_threaded_mainloop_signal(data->loop_, 0);
}

}  // namespace

bool InitPulse(pa_threaded_mainloop** mainloop, pa_context** context) {
#if defined(DLOPEN_PULSEAUDIO)
  StubPathMap paths;

  // Check if the pulse library is avialbale.
  paths[kModulePulse].push_back(kPulseLib);
  if (!InitializeStubs(paths)) {
    VLOG(1) << "Failed on loading the Pulse library and symbols";
    return false;
  }
#endif  // defined(DLOPEN_PULSEAUDIO)

  // The setup order below follows the pattern used by pa_simple_new():
  // https://github.com/pulseaudio/pulseaudio/blob/master/src/pulse/simple.c

  // Create a mainloop API and connect to the default server.
  // The mainloop is the internal asynchronous API event loop.
  pa_threaded_mainloop* pa_mainloop = pa_threaded_mainloop_new();
  if (!pa_mainloop)
    return false;

  pa_mainloop_api* pa_mainloop_api = pa_threaded_mainloop_get_api(pa_mainloop);
  pa_context* pa_context = pa_context_new(pa_mainloop_api, "Chrome input");
  if (!pa_context) {
    pa_threaded_mainloop_free(pa_mainloop);
    return false;
  }

  pa_context_set_state_callback(pa_context, &pulse::ContextStateCallback,
                                pa_mainloop);
  if (pa_context_connect(pa_context, NULL, PA_CONTEXT_NOAUTOSPAWN, NULL)) {
    VLOG(1) << "Failed to connect to the context.  Error: "
            << pa_strerror(pa_context_errno(pa_context));
    pa_context_set_state_callback(pa_context, NULL, NULL);
    pa_context_unref(pa_context);
    pa_threaded_mainloop_free(pa_mainloop);
    return false;
  }

  // Lock the event loop object, effectively blocking the event loop thread
  // from processing events. This is necessary.
  auto mainloop_lock = std::make_unique<AutoPulseLock>(pa_mainloop);

  // Start the threaded mainloop after everything has been configured.
  if (pa_threaded_mainloop_start(pa_mainloop)) {
    mainloop_lock.reset();
    DestroyMainloop(pa_mainloop);
    return false;
  }

  // Wait until |pa_context| is ready.  pa_threaded_mainloop_wait() must be
  // called after pa_context_get_state() in case the context is already ready,
  // otherwise pa_threaded_mainloop_wait() will hang indefinitely.
  while (true) {
    pa_context_state_t context_state = pa_context_get_state(pa_context);
    if (!PA_CONTEXT_IS_GOOD(context_state)) {
      DestroyContext(pa_context);
      mainloop_lock.reset();
      DestroyMainloop(pa_mainloop);
      return false;
    }
    if (context_state == PA_CONTEXT_READY)
      break;
    pa_threaded_mainloop_wait(pa_mainloop);
  }

  *mainloop = pa_mainloop;
  *context = pa_context;
  return true;
}

void DestroyPulse(pa_threaded_mainloop* mainloop, pa_context* context) {
  DCHECK(mainloop);
  DCHECK(context);

  {
    AutoPulseLock auto_lock(mainloop);
    DestroyContext(context);
  }

  DestroyMainloop(mainloop);
}

// static, pa_stream_success_cb_t
void StreamSuccessCallback(pa_stream* s, int error, void* mainloop) {
  pa_threaded_mainloop* pa_mainloop =
      static_cast<pa_threaded_mainloop*>(mainloop);
  pa_threaded_mainloop_signal(pa_mainloop, 0);
}

// |pa_context| and |pa_stream| state changed cb.
void ContextStateCallback(pa_context* context, void* mainloop) {
  pa_threaded_mainloop* pa_mainloop =
      static_cast<pa_threaded_mainloop*>(mainloop);
  pa_threaded_mainloop_signal(pa_mainloop, 0);
}

pa_channel_map ChannelLayoutToPAChannelMap(ChannelLayout channel_layout) {
  pa_channel_map channel_map;
  if (channel_layout == CHANNEL_LAYOUT_MONO) {
    // CHANNEL_LAYOUT_MONO only specifies audio on the C channel, but we
    // want PulseAudio to play single-channel audio on more than just that.
    pa_channel_map_init_mono(&channel_map);
  } else {
    pa_channel_map_init(&channel_map);

    channel_map.channels = ChannelLayoutToChannelCount(channel_layout);
    for (Channels ch = LEFT; ch <= CHANNELS_MAX;
         ch = static_cast<Channels>(ch + 1)) {
      int channel_index = ChannelOrder(channel_layout, ch);
      if (channel_index < 0)
        continue;

      channel_map.map[channel_index] = ChromiumToPAChannelPosition(ch);
    }
  }

  return channel_map;
}

void WaitForOperationCompletion(pa_threaded_mainloop* pa_mainloop,
                                pa_operation* operation) {
  if (!operation) {
    DLOG(WARNING) << "Operation is NULL";
    return;
  }

  while (pa_operation_get_state(operation) == PA_OPERATION_RUNNING)
    pa_threaded_mainloop_wait(pa_mainloop);

  pa_operation_unref(operation);
}

base::TimeDelta GetHardwareLatency(pa_stream* stream) {
  DCHECK(stream);
  int negative = 0;
  pa_usec_t latency_micros = 0;
  if (pa_stream_get_latency(stream, &latency_micros, &negative) != 0)
    return base::TimeDelta();

  if (negative)
    return base::TimeDelta();

  return base::TimeDelta::FromMicroseconds(latency_micros);
}

// Helper macro for CreateInput/OutputStream() to avoid code spam and
// string bloat.
#define RETURN_ON_FAILURE(expression, message) do { \
  if (!(expression)) { \
    DLOG(ERROR) << message; \
    return false; \
  } \
} while (0)

bool CreateInputStream(pa_threaded_mainloop* mainloop,
                       pa_context* context,
                       pa_stream** stream,
                       const AudioParameters& params,
                       const std::string& device_id,
                       pa_stream_notify_cb_t stream_callback,
                       void* user_data) {
  DCHECK(mainloop);
  DCHECK(context);

  // Set sample specifications.
  pa_sample_spec sample_specifications;

  // FIXME: This should be PA_SAMPLE_FLOAT32, but there is more work needed in
  // PulseAudioInputStream to support this.
  static_assert(kInputSampleFormat == kSampleFormatS16,
                "Only 16-bit input supported.");
  sample_specifications.format = PA_SAMPLE_S16LE;
  sample_specifications.rate = params.sample_rate();
  sample_specifications.channels = params.channels();

  // Get channel mapping and open recording stream.
  pa_channel_map source_channel_map = ChannelLayoutToPAChannelMap(
      params.channel_layout());
  pa_channel_map* map = (source_channel_map.channels != 0) ?
      &source_channel_map : NULL;

  // Create a new recording stream and
  // tells PulseAudio what the stream icon should be.
  ScopedPropertyList property_list;
  pa_proplist_sets(property_list.get(), PA_PROP_APPLICATION_ICON_NAME,
                   kBrowserDisplayName);
  *stream = pa_stream_new_with_proplist(context, "RecordStream",
                                        &sample_specifications, map,
                                        property_list.get());
  RETURN_ON_FAILURE(*stream, "failed to create PA recording stream");

  pa_stream_set_state_callback(*stream, stream_callback, user_data);

  // Set server-side capture buffer metrics. Detailed documentation on what
  // values should be chosen can be found at
  // freedesktop.org/software/pulseaudio/doxygen/structpa__buffer__attr.html.
  pa_buffer_attr buffer_attributes;
  const unsigned int buffer_size = params.GetBytesPerBuffer(kInputSampleFormat);
  buffer_attributes.maxlength = static_cast<uint32_t>(-1);
  buffer_attributes.tlength = buffer_size;
  buffer_attributes.minreq = buffer_size;
  buffer_attributes.prebuf = static_cast<uint32_t>(-1);
  buffer_attributes.fragsize = buffer_size;
  int flags = PA_STREAM_AUTO_TIMING_UPDATE |
              PA_STREAM_INTERPOLATE_TIMING |
              PA_STREAM_ADJUST_LATENCY |
              PA_STREAM_START_CORKED;
  RETURN_ON_FAILURE(
      pa_stream_connect_record(
          *stream, device_id == AudioDeviceDescription::kDefaultDeviceId
                       ? NULL
                       : device_id.c_str(),
          &buffer_attributes, static_cast<pa_stream_flags_t>(flags)) == 0,
      "pa_stream_connect_record FAILED ");

  // Wait for the stream to be ready.
  while (true) {
    pa_stream_state_t stream_state = pa_stream_get_state(*stream);
    RETURN_ON_FAILURE(
        PA_STREAM_IS_GOOD(stream_state), "Invalid PulseAudio stream state");
    if (stream_state == PA_STREAM_READY)
        break;
    pa_threaded_mainloop_wait(mainloop);
  }

  return true;
}

bool CreateOutputStream(pa_threaded_mainloop** mainloop,
                        pa_context** context,
                        pa_stream** stream,
                        const AudioParameters& params,
                        const std::string& device_id,
                        const std::string& app_name,
                        pa_stream_notify_cb_t stream_callback,
                        pa_stream_request_cb_t write_callback,
                        void* user_data) {
  DCHECK(!*mainloop);
  DCHECK(!*context);

  *mainloop = pa_threaded_mainloop_new();
  RETURN_ON_FAILURE(*mainloop, "Failed to create PulseAudio main loop.");

  pa_mainloop_api* pa_mainloop_api = pa_threaded_mainloop_get_api(*mainloop);
  *context = pa_context_new(pa_mainloop_api,
                            app_name.empty() ? "Chromium" : app_name.c_str());
  RETURN_ON_FAILURE(*context, "Failed to create PulseAudio context.");

  // A state callback must be set before calling pa_threaded_mainloop_lock() or
  // pa_threaded_mainloop_wait() calls may lead to dead lock.
  pa_context_set_state_callback(*context, &ContextStateCallback, *mainloop);

  // Lock the main loop while setting up the context.  Failure to do so may lead
  // to crashes as the PulseAudio thread tries to run before things are ready.
  AutoPulseLock auto_lock(*mainloop);

  RETURN_ON_FAILURE(pa_threaded_mainloop_start(*mainloop) == 0,
                    "Failed to start PulseAudio main loop.");
  RETURN_ON_FAILURE(
      pa_context_connect(*context, NULL, PA_CONTEXT_NOAUTOSPAWN, NULL) == 0,
      "Failed to connect PulseAudio context.");

  // Wait until |pa_context_| is ready.  pa_threaded_mainloop_wait() must be
  // called after pa_context_get_state() in case the context is already ready,
  // otherwise pa_threaded_mainloop_wait() will hang indefinitely.
  while (true) {
    pa_context_state_t context_state = pa_context_get_state(*context);
    RETURN_ON_FAILURE(PA_CONTEXT_IS_GOOD(context_state),
                      "Invalid PulseAudio context state.");
    if (context_state == PA_CONTEXT_READY)
      break;
    pa_threaded_mainloop_wait(*mainloop);
  }

  // Set sample specifications.
  pa_sample_spec sample_specifications;
  sample_specifications.format = PA_SAMPLE_FLOAT32;
  sample_specifications.rate = params.sample_rate();
  sample_specifications.channels = params.channels();

  // Get channel mapping.
  pa_channel_map* map = NULL;
  pa_channel_map source_channel_map = ChannelLayoutToPAChannelMap(
      params.channel_layout());
  if (source_channel_map.channels != 0) {
    // The source data uses a supported channel map so we will use it rather
    // than the default channel map (NULL).
    map = &source_channel_map;
  }

  // Open playback stream and
  // tell PulseAudio what the stream icon should be.
  ScopedPropertyList property_list;
  pa_proplist_sets(property_list.get(), PA_PROP_APPLICATION_ICON_NAME,
                   kBrowserDisplayName);
  *stream = pa_stream_new_with_proplist(
      *context, "Playback", &sample_specifications, map, property_list.get());
  RETURN_ON_FAILURE(*stream, "failed to create PA playback stream");

  pa_stream_set_state_callback(*stream, stream_callback, user_data);

  // Even though we start the stream corked above, PulseAudio will issue one
  // stream request after setup.  write_callback() must fulfill the write.
  pa_stream_set_write_callback(*stream, write_callback, user_data);

  // Pulse is very finicky with the small buffer sizes used by Chrome.  The
  // settings below are mostly found through trial and error.  Essentially we
  // want Pulse to auto size its internal buffers, but call us back nearly every
  // |minreq| bytes.  |tlength| should be a multiple of |minreq|; too low and
  // Pulse will issue callbacks way too fast, too high and we don't get
  // callbacks frequently enough.
  //
  // Setting |minreq| to the exact buffer size leads to more callbacks than
  // necessary, so we've clipped it to half the buffer size.  Regardless of the
  // requested amount, we'll always fill |params.GetBytesPerBuffer()| though.
  size_t buffer_size = params.GetBytesPerBuffer(kSampleFormatF32);
  pa_buffer_attr pa_buffer_attributes;
  pa_buffer_attributes.maxlength = static_cast<uint32_t>(-1);
  pa_buffer_attributes.minreq = buffer_size / 2;
  pa_buffer_attributes.prebuf = static_cast<uint32_t>(-1);
  pa_buffer_attributes.tlength = buffer_size * 3;
  pa_buffer_attributes.fragsize = static_cast<uint32_t>(-1);

  // Connect playback stream.  Like pa_buffer_attr, the pa_stream_flags have a
  // huge impact on the performance of the stream and were chosen through trial
  // and error.
  RETURN_ON_FAILURE(
      pa_stream_connect_playback(
          *stream, device_id == AudioDeviceDescription::kDefaultDeviceId
                       ? NULL
                       : device_id.c_str(),
          &pa_buffer_attributes,
          static_cast<pa_stream_flags_t>(
              PA_STREAM_INTERPOLATE_TIMING | PA_STREAM_ADJUST_LATENCY |
              PA_STREAM_AUTO_TIMING_UPDATE | PA_STREAM_NOT_MONOTONIC |
              PA_STREAM_START_CORKED),
          NULL, NULL) == 0,
      "pa_stream_connect_playback FAILED ");

  // Wait for the stream to be ready.
  while (true) {
    pa_stream_state_t stream_state = pa_stream_get_state(*stream);
    RETURN_ON_FAILURE(
        PA_STREAM_IS_GOOD(stream_state), "Invalid PulseAudio stream state");
    if (stream_state == PA_STREAM_READY)
      break;
    pa_threaded_mainloop_wait(*mainloop);
  }

  return true;
}

std::string GetBusOfInput(pa_threaded_mainloop* mainloop,
                          pa_context* context,
                          const std::string& name) {
  DCHECK(mainloop);
  DCHECK(context);
  AutoPulseLock auto_lock(mainloop);
  InputBusData data(mainloop, name);
  pa_operation* operation =
      pa_context_get_source_info_list(context, InputBusCallback, &data);
  WaitForOperationCompletion(mainloop, operation);
  return data.bus_;
}

std::string GetOutputCorrespondingTo(pa_threaded_mainloop* mainloop,
                                     pa_context* context,
                                     const std::string& bus) {
  DCHECK(mainloop);
  DCHECK(context);
  AutoPulseLock auto_lock(mainloop);
  OutputBusData data(mainloop, bus);
  pa_operation* operation =
      pa_context_get_sink_info_list(context, OutputBusCallback, &data);
  WaitForOperationCompletion(mainloop, operation);
  return data.name_;
}

std::string GetRealDefaultDeviceId(pa_threaded_mainloop* mainloop,
                                   pa_context* context,
                                   RequestType type) {
  DCHECK(mainloop);
  DCHECK(context);
  AutoPulseLock auto_lock(mainloop);
  DefaultDevicesData data(mainloop);
  pa_operation* operation =
      pa_context_get_server_info(context, &GetDefaultDeviceIdCallback, &data);
  WaitForOperationCompletion(mainloop, operation);
  return (type == RequestType::INPUT) ? data.input_ : data.output_;
}

#undef RETURN_ON_FAILURE

}  // namespace pulse

}  // namespace media