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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/capture_mode/audio_capturer.h"
#include "base/functional/bind.h"
#include "base/sequence_checker.h"
#include "media/base/audio_bus.h"
#include "services/audio/public/cpp/device_factory.h"
namespace capture_mode {
namespace {
constexpr int kPreAllocatedBuses = 5;
constexpr int kMaxBusCapacity = 10;
} // namespace
AudioCapturer::AudioCapturer(
std::string_view device_id,
mojo::PendingRemote<media::mojom::AudioStreamFactory> audio_stream_factory,
const media::AudioParameters& audio_params,
OnAudioCapturedCallback callback)
: audio_capturer_(
audio::CreateInputDevice(std::move(audio_stream_factory),
std::string(device_id),
audio::DeadStreamDetection::kEnabled)),
on_audio_captured_callback_(std::move(callback)),
audio_bus_pool_(audio_params, kPreAllocatedBuses, kMaxBusCapacity) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
weak_ptr_this_ = weak_ptr_factory_.GetWeakPtr();
audio_capturer_->Initialize(audio_params, /*callback=*/this);
}
AudioCapturer::~AudioCapturer() = default;
void AudioCapturer::Start() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
audio_capturer_->Start();
}
void AudioCapturer::Stop() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
audio_capturer_->Stop();
}
void AudioCapturer::OnCaptureStarted() {}
void AudioCapturer::Capture(const media::AudioBus* audio_source,
base::TimeTicks audio_capture_time,
const media::AudioGlitchInfo& glitch_info,
double volume) {
// This is called on a worker thread created by the `audio_capturer_` (See
// `media::AudioDeviceThread`. The given `audio_source` wraps audio data in a
// shared memory with the audio service. Calling `audio_capturer_->Stop()`
// will destroy that thread and the shared memory mapping before we get a
// chance to encode and flush the remaining frames (See
// `media::AudioInputDevice::Stop()`, and
// `media::AudioInputDevice::AudioThreadCallback::Process()` for details). It
// is safer that we own our AudioBuses that are kept alive until encoded and
// flushed.
// We need to avoid allocating new audio buses here, since this is running on
// the realtime audio thread, hence we use the audio bus pool.
auto backing_audio_bus = audio_bus_pool_.GetAudioBus();
DCHECK_EQ(backing_audio_bus->frames(), audio_source->frames());
DCHECK_EQ(backing_audio_bus->channels(), audio_source->channels());
audio_source->CopyTo(backing_audio_bus.get());
// However, the audio bus pool requires that we return back the audio bus when
// we're done with it, so it can be reused. Therefore we will create another
// audio bus that acts as a wrapper around the `backing_audio_bus` we got from
// the pool. The `wrapping_audio_bus` will be the one we provide to the client
// via `on_audio_captured_callback_`. Once the client is done with it, and it
// goes out of scope, the `backing_audio_bus` will be returned back to the
// pool in `OnAudioBusDone()`.
auto wrapping_audio_bus =
media::AudioBus::CreateWrapper(backing_audio_bus->channels());
wrapping_audio_bus->set_frames(backing_audio_bus->frames());
wrapping_audio_bus->SetAllChannels(backing_audio_bus->AllChannels());
// Keep `backing_audio_bus` alive as long as `wrapping_audio_bus` by
// transferring its ownership to the `wrapping_audio_bus`'s deleter callback.
wrapping_audio_bus->SetWrappedDataDeleter(
base::BindOnce(&AudioCapturer::OnAudioBusDone, weak_ptr_this_,
std::move(backing_audio_bus)));
on_audio_captured_callback_.Run(std::move(wrapping_audio_bus),
audio_capture_time);
}
void AudioCapturer::OnCaptureError(media::AudioCapturerSource::ErrorCode code,
const std::string& message) {
LOG(ERROR) << "AudioCaptureError: code=" << static_cast<uint32_t>(code)
<< ", " << message;
}
void AudioCapturer::OnCaptureMuted(bool is_muted) {}
void AudioCapturer::OnAudioBusDone(
std::unique_ptr<media::AudioBus> backing_audio_bus) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
audio_bus_pool_.InsertAudioBus(std::move(backing_audio_bus));
}
} // namespace capture_mode
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