Adding pulseaudio input support to chrome

media/audio/pulse/pulse_input.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_input.h"
+
+#include "base/logging.h"
+#include "media/audio/linux/audio_manager_linux.h"
+#include "media/audio/pulse/pulse_util.h"
+#include "media/base/seekable_buffer.h"
+
+namespace media {
+
+PulseAudioInputStream::PulseAudioInputStream(AudioManagerLinux* audio_manager,
+                                             const std::string& device_name,
+                                             const AudioParameters& params,
+                                             pa_threaded_mainloop* mainloop,
+                                             pa_context* context)
+    : audio_manager_(audio_manager),
+      callback_(NULL),
+      device_name_(device_name),
+      params_(params),
+      channels_(0),
+      volume_(0.0),
+      stream_started_(false),
+      pa_mainloop_(mainloop),
+      pa_context_(context),
+      handle_(NULL) {
+  DCHECK(audio_manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(mainloop);
+  DCHECK(context);
+}
+
+PulseAudioInputStream::~PulseAudioInputStream() {
+  // All internal structures should already have been freed in Close(),
+  // which calls AudioManagerPulse::Release which deletes this object.
+  DCHECK(!handle_);
+}
+
+bool PulseAudioInputStream::Open() {
+  DCHECK(audio_manager_->GetMessageLoop()->BelongsToCurrentThread());
+  AutoPulseLock auto_lock(pa_mainloop_);
+
+  // Set sample specifications.
+  pa_sample_spec pa_sample_specifications;
+  pa_sample_specifications.format = BitsToPASampleFormat(
+      params_.bits_per_sample());
+  pa_sample_specifications.rate = params_.sample_rate();
+  pa_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.
+  handle_ = pa_stream_new(pa_context_, "RecordStream",
+                          &pa_sample_specifications, map);
+  if (!handle_) {
+    DLOG(ERROR) << "Open: failed to create PA stream";
+    return false;
+  }
+
+  pa_stream_set_state_callback(handle_, &StreamNotifyCallback, this);
+  pa_stream_set_read_callback(handle_, &ReadCallback, this);
+  pa_stream_readable_size(handle_);
+
+  // 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();
+  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;
+  int err = pa_stream_connect_record(
+      handle_,
+      device_name_ == AudioManagerBase::kDefaultDeviceId ?
+          NULL : device_name_.c_str(),
+      &buffer_attributes,
+      static_cast<pa_stream_flags_t>(flags));
+  if (err) {
+    DLOG(ERROR) << "pa_stream_connect_playback FAILED " << err;
+    return false;
+  }
+
+  // Wait for the stream to be ready.
+  while (true) {
+    pa_stream_state_t stream_state = pa_stream_get_state(handle_);
+    if(!PA_STREAM_IS_GOOD(stream_state)) {
+      DLOG(ERROR) << "Invalid PulseAudio stream state";
+      return false;
+    }
+
+    if (stream_state == PA_STREAM_READY)
+      break;
+    pa_threaded_mainloop_wait(pa_mainloop_);
+  }
+
+  pa_stream_set_read_callback(handle_, &ReadCallback, this);
+  pa_stream_readable_size(handle_);
+
+  buffer_.reset(new media::SeekableBuffer(0, 2 * params_.GetBytesPerBuffer()));
+  audio_data_buffer_.reset(new uint8[params_.GetBytesPerBuffer()]);
+  return true;
+}
+
+void PulseAudioInputStream::Start(AudioInputCallback* callback) {
+  DCHECK(audio_manager_->GetMessageLoop()->BelongsToCurrentThread());
+  DCHECK(callback);
+  DCHECK(handle_);
+  AutoPulseLock auto_lock(pa_mainloop_);
+
+  if (stream_started_)
+    return;
+
+  // Clean up the old buffer.
+  pa_stream_drop(handle_);
+
+  // Start the streaming.
+  stream_started_ = true;
+  callback_ = callback;
+
+  pa_operation* operation = pa_stream_cork(handle_, 0, NULL, NULL);

[DaleCurtis, 2013/01/30 02:54:30]

Do you need to wait for this? I do in PulseOutput.

[no longer working on chromium, 2013/02/12 17:35:59]

I think both work, but make more sense to wait here.

+  if (!operation) {
+    DLOG(ERROR) << "Failed to start the recording stream";
+    return;
+  }
+  pa_operation_unref(operation);
+}
+
+void PulseAudioInputStream::Stop() {
+  DCHECK(audio_manager_->GetMessageLoop()->BelongsToCurrentThread());
+  AutoPulseLock auto_lock(pa_mainloop_);
+  if (!stream_started_)
+    return;
+
+  // Set the flag to false to stop filling new data to soundcard.
+  stream_started_ = false;
+

[DaleCurtis, 2013/01/30 02:54:30]

Need to flush?

[no longer working on chromium, 2013/02/12 17:35:59]

Done.

+  // Stop the stream.
+  pa_stream_set_read_callback(handle_, NULL, NULL);
+  pa_operation* operation = pa_stream_cork(handle_, 1, &StreamSuccessCallback,
+                                           pa_mainloop_);
+  if (!operation) {
+    DLOG(ERROR) << "PulseAudioInputStream: failed to stop the recording";
+    return;
+  }
+
+  WaitForOperationCompletion(pa_mainloop_, operation);
+}
+
+void PulseAudioInputStream::Close() {
+  DCHECK(audio_manager_->GetMessageLoop()->BelongsToCurrentThread());
+  {
+    AutoPulseLock auto_lock(pa_mainloop_);
+    if (handle_) {
+      // Disable all the callbacks before disconnecting.
+      pa_stream_set_state_callback(handle_, NULL, NULL);
+      pa_stream_flush(handle_, NULL, NULL);
+
+      if (pa_stream_get_state(handle_) != PA_STREAM_UNCONNECTED)
+        pa_stream_disconnect(handle_);
+
+      // Release PulseAudio structures.
+      pa_stream_unref(handle_);
+      handle_ = NULL;
+    }
+  }
+
+  if (callback_)
+    callback_->OnClose(this);
+
+  // Signal to the manager that we're closed and can be removed.
+  // This should be the last call in the function as it deletes "this".
+  audio_manager_->ReleaseInputStream(this);
+}
+
+double PulseAudioInputStream::GetMaxVolume() {
+  return static_cast<double>(PA_VOLUME_NORM);
+}
+
+void PulseAudioInputStream::SetVolume(double volume) {

[DaleCurtis, 2013/01/30 02:54:30]

Slightly off topic, but does WebRTC or anything actually use all the
Get/SetVolume stuff? I'm thinking of removing it throughout the code base. HTML5
volume will be handled by renderer side mixing. At least on the output side that
would get rid of a bunch of useless AdjustVolume calls.

I see something about the AGC using volume below, but I'm unfamiliar with how
this all fits together.

[no longer working on chromium, 2013/02/12 17:35:59]

Yes, WebRtc analog AGC needs these analog volume control.

+  AutoPulseLock auto_lock(pa_mainloop_);
+  if (!handle_)
+    return;
+
+  size_t index = pa_stream_get_device_index(handle_);
+  pa_operation* operation = NULL;
+  if (!channels_) {
+    // Get the number of channels for the source only when the |channels_| is 0.
+    // We are assuming the stream source is not changed on the fly here.
+    operation = pa_context_get_source_info_by_index(
+        pa_context_, index, &VolumeCallback, this);
+    WaitForOperationCompletion(pa_mainloop_, operation);
+    if (!channels_) {
+      DLOG(WARNING) << "Failed to get the number of channels for the source";
+      return;
+    }
+  }
+
+  pa_cvolume pa_volume;
+  pa_cvolume_set(&pa_volume, channels_, volume);

[DaleCurtis, 2013/01/30 02:54:30]

Weird that you need the channels_ here. Do you know why?

[no longer working on chromium, 2013/02/12 17:35:59]

The API description looks like this:
Set the volume of the specified number of channels to the volume v.

So I assume we need to know the number of channels of the device before setting
the volume.

+  operation = pa_context_set_source_volume_by_index(
+      pa_context_, index, &pa_volume, NULL, NULL);
+
+  // Don't need to wait for this task to complete.
+  pa_operation_unref(operation);
+}
+
+double PulseAudioInputStream::GetVolume() {
+  AutoPulseLock auto_lock(pa_mainloop_);
+  if (!handle_)
+    return 0.0;
+
+  size_t index = pa_stream_get_device_index(handle_);
+  pa_operation* operation = pa_context_get_source_info_by_index(
+      pa_context_, index, &VolumeCallback, this);
+  WaitForOperationCompletion(pa_mainloop_, operation);
+
+  return volume_;
+}
+
+// static, used by pa_stream_set_read_callback.
+void PulseAudioInputStream::ReadCallback(pa_stream* handle,
+                                         size_t length,
+                                         void* user_data) {
+  PulseAudioInputStream* stream =
+      reinterpret_cast<PulseAudioInputStream*>(user_data);
+
+  stream->ReadData();
+}
+
+// static, used by pa_context_get_source_info_by_index.
+void PulseAudioInputStream::VolumeCallback(pa_context* context,
+                                           const pa_source_info* info,
+                                           int error, void* user_data) {
+  PulseAudioInputStream* stream =
+      reinterpret_cast<PulseAudioInputStream*>(user_data);
+
+  if (error) {
+    pa_threaded_mainloop_signal(stream->pa_mainloop_, 0);
+    return;
+  }
+
+  if (stream->channels_ != info->channel_map.channels)
+    stream->channels_ = info->channel_map.channels;
+
+  pa_volume_t volume = PA_VOLUME_MUTED; // Minimum possible value.
+  // Use the max volume of any channel as the volume.
+  for (int i = 0; i < stream->channels_; ++i) {
+    if (volume < info->volume.values[i])
+      volume = info->volume.values[i];
+  }
+
+  stream->volume_ = static_cast<double>(volume);
+}
+
+// static, used by pa_stream_set_state_callback.
+void PulseAudioInputStream::StreamNotifyCallback(pa_stream* stream,
+                                                 void* user_data) {
+  PulseAudioInputStream* pulse_stream =
+      reinterpret_cast<PulseAudioInputStream*>(user_data);
+  if (stream && pulse_stream->callback_ &&
+      pa_stream_get_state(stream) == PA_STREAM_FAILED) {
+    pulse_stream->callback_->OnError(
+        pulse_stream, pa_context_errno(pulse_stream->pa_context_));
+  }
+
+  pa_threaded_mainloop_signal(pulse_stream->pa_mainloop_, 0);
+}
+
+int PulseAudioInputStream::GetHardwareLatencyInBytes() {

[DaleCurtis, 2013/01/30 02:54:30]

Is this something that should be in PulseUtil?

[no longer working on chromium, 2013/02/12 17:35:59]

Done.

+  int negative = 0;
+  pa_usec_t latency_micros = 0;
+  if (pa_stream_get_latency(handle_, &latency_micros, &negative) != 0)
+    return 0;
+
+  if (negative)
+    return 0;
+
+  return (latency_micros * params_.sample_rate() *
+      params_.GetBytesPerFrame()) / base::Time::kMicrosecondsPerSecond;
+}
+
+void PulseAudioInputStream::ReadData() {
+  uint32 hardware_delay = GetHardwareLatencyInBytes();
+
+  // Update the AGC volume level once every second. Note that,
+  // |volume| is also updated each time SetVolume() is called
+  // through IPC by the render-side AGC.
+  double normalized_volume = 0.0;
+  QueryAgcVolume(&normalized_volume);
+
+  while (true) {
+    size_t length = 0;
+    const void* data = NULL;
+    pa_stream_peek(handle_, &data, &length);

[DaleCurtis, 2013/01/30 02:54:30]

Does this length correlate well with the requested length? I.e. is it frequently
not what we requested? I'm worried our read callbacks will have infrequent
(read: high latency) timing.

[no longer working on chromium, 2013/02/12 17:35:59]

most of the cases it is the same as the requested length. but if overrun
happens, this might change, but I am not sure.

+    if (!data || length == 0)
+      break;
+
+    buffer_->Append(reinterpret_cast<const uint8*>(data), length);
+
+    // Checks if we still have data.
+    pa_stream_drop(handle_);
+    if (pa_stream_readable_size(handle_) <= 0)
+      break;
+  }
+
+  int packet_size = params_.GetBytesPerBuffer();
+  while (buffer_->forward_bytes() >= packet_size) {

[DaleCurtis, 2013/01/30 02:54:30]

Following up on the last comment, for this to work in a reliable manner, the
pulse callback must happen more frequently than we expect it to.

[no longer working on chromium, 2013/02/12 17:35:59]

Right, if this can happen, we might need something like WaitTillDataReady on the
input side to handle the asynchronous share memory. I put a sleep for 2ms for
now, and will revisit it if we see the need for WaitTillDataReady.

+    buffer_->Read(audio_data_buffer_.get(), packet_size);
+    callback_->OnData(this, audio_data_buffer_.get(),  packet_size,
+                      hardware_delay, normalized_volume);
+  }
+
+  pa_threaded_mainloop_signal(pa_mainloop_, 0);
+}
+
+}  // namespace media