blob: 638459a0b4b6ab7cc1f6e10a59bdf1a07da7bc7d [file] [log] [blame]
// 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.
// Creates an audio output stream based on the PulseAudio asynchronous API;
// specifically using the pa_threaded_mainloop model.
// If the stream is successfully opened, Close() must be called before the
// stream is deleted as Close() is responsible for ensuring resource cleanup
// occurs.
// This object is designed so that all AudioOutputStream methods will be called
// on the same thread that created the object.
// WARNING: This object blocks on internal PulseAudio calls in Open() while
// waiting for PulseAudio's context structure to be ready. It also blocks in
// inside PulseAudio in Start() and repeated during playback, waiting for
// PulseAudio write callbacks to occur.
#include <stddef.h>
#include <memory>
#include <string>
#include "base/macros.h"
#include "base/threading/thread_checker.h"
#include "media/audio/audio_io.h"
#include "media/base/audio_parameters.h"
struct pa_context;
struct pa_stream;
struct pa_threaded_mainloop;
namespace media {
class AudioManagerBase;
class PulseAudioOutputStream : public AudioOutputStream {
PulseAudioOutputStream(const AudioParameters& params,
const std::string& device_id,
AudioManagerBase* manager);
~PulseAudioOutputStream() override;
// Implementation of AudioOutputStream.
bool Open() override;
void Close() override;
void Flush() override;
void Start(AudioSourceCallback* callback) override;
void Stop() override;
void SetVolume(double volume) override;
void GetVolume(double* volume) override;
// Called by PulseAudio when |pa_stream_| change state. If an unexpected
// failure state change happens and |source_callback_| is set
// this method will forward the error via OnError().
static void StreamNotifyCallback(pa_stream* s, void* p_this);
// Called by PulseAudio when it needs more audio data.
static void StreamRequestCallback(pa_stream* s, size_t len, void* p_this);
// Fulfill a write request from the write request callback. Outputs silence
// if the request could not be fulfilled.
void FulfillWriteRequest(size_t requested_bytes);
// Close() helper function to free internal structs.
void Reset();
// AudioParameters from the constructor.
const AudioParameters params_;
// The device ID for the device to open.
const std::string device_id_;
// Audio manager that created us. Used to report that we've closed.
AudioManagerBase* manager_;
// PulseAudio API structs.
pa_context* pa_context_;
pa_threaded_mainloop* pa_mainloop_;
pa_stream* pa_stream_;
// Float representation of volume from 0.0 to 1.0.
float volume_;
// Callback to audio data source. Must only be modified while holding a lock
// on |pa_mainloop_| via pa_threaded_mainloop_lock().
AudioSourceCallback* source_callback_;
// Container for retrieving data from AudioSourceCallback::OnMoreData().
std::unique_ptr<AudioBus> audio_bus_;
const size_t buffer_size_;
base::ThreadChecker thread_checker_;
} // namespace media