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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_SCHEDULED_SOURCE_HANDLER_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_SCHEDULED_SOURCE_HANDLER_H_
#include <atomic>
#include "base/memory/weak_ptr.h"
#include "base/task/single_thread_task_runner.h"
#include "base/thread_annotations.h"
#include "third_party/blink/renderer/bindings/core/v8/active_script_wrappable.h"
#include "third_party/blink/renderer/modules/webaudio/audio_node.h"
namespace blink {
class BaseAudioContext;
class AudioBus;
class AudioScheduledSourceHandler : public AudioHandler {
public:
// These are the possible states an AudioScheduledSourceNode can be in:
//
// UNSCHEDULED_STATE - Initial playback state. Created, but not yet scheduled.
// SCHEDULED_STATE - Scheduled to play (via start()), but not yet playing.
// PLAYING_STATE - Generating sound.
// FINISHED_STATE - Finished generating sound.
//
// The state can only transition to the next state, except for the
// FINISHED_STATE which can never be changed.
enum PlaybackState {
// These must be defined with the same names and values as in the .idl file.
UNSCHEDULED_STATE = 0,
SCHEDULED_STATE = 1,
PLAYING_STATE = 2,
FINISHED_STATE = 3
};
AudioScheduledSourceHandler(NodeType, AudioNode&, float sample_rate);
// Scheduling.
void Start(double when, ExceptionState&);
void Stop(double when, ExceptionState&);
// AudioNode
double TailTime() const override { return 0; }
double LatencyTime() const override { return 0; }
PlaybackState GetPlaybackState() const {
return playback_state_.load(std::memory_order_acquire);
}
void SetPlaybackState(PlaybackState new_state) {
playback_state_.store(new_state, std::memory_order_release);
}
bool IsPlayingOrScheduled() const {
PlaybackState state = GetPlaybackState();
return state == PLAYING_STATE || state == SCHEDULED_STATE;
}
bool HasFinished() const { return GetPlaybackState() == FINISHED_STATE; }
// Source nodes don't have tail or latency times so no tail
// processing needed.
bool RequiresTailProcessing() const final { return false; }
// Stops a node if the stop time has passed. Generally used when a source
// node has been scheduled to start but has disconnected some time before the
// stop time has arrived. Nodes that are not reachable from the destination
// don't progress in time so we need to handle this specially.
virtual void HandleStoppableSourceNode() = 0;
// Returns true if the onended event has not been sent (is pending).
bool IsOnEndedNotificationPending() const {
return on_ended_notification_pending_;
}
void SetOnEndedNotificationPending() {
on_ended_notification_pending_ = true;
}
protected:
// Get frame information for the current time quantum.
// We handle the transition into PLAYING_STATE and FINISHED_STATE here,
// zeroing out portions of the outputBus which are outside the range of
// startFrame and endFrame.
//
// Each frame time is relative to the context's currentSampleFrame(). Three
// values are returned, in this order:
//
// quantumFrameOffset : Offset frame in this time quantum to start
// rendering.
// nonSilentFramesToProcess : Number of frames rendering non-silence (will be
// <= quantumFrameSize).
// startFrameOffset : The fractional frame offset from quantumFrameOffset
// and the actual starting time of the source. This is
// non-zero only when transitioning from the
// SCHEDULED_STATE to the PLAYING_STATE.
//
// Callers should check nonSilentFramesToProcess to decide what to
// do. If it is zero, the other return values are meaningless.
std::tuple<size_t, size_t, double> UpdateSchedulingInfo(
size_t quantum_frame_size,
AudioBus* output_bus) EXCLUSIVE_LOCKS_REQUIRED(process_lock_);
// Called when we have no more sound to play or the stop() time has been
// reached. No onEnded event is called.
virtual void FinishWithoutOnEnded();
// Like finishWithoutOnEnded(), but an onEnded (if specified) is called.
virtual void Finish();
void NotifyEnded();
// This synchronizes with process() and any other method that needs to be
// synchronized like setBuffer for AudioBufferSource.
mutable base::Lock process_lock_;
// |start_time_| is the time to start playing based on the context's timeline
// (0 or a time less than the context's current time means "now").
double start_time_ GUARDED_BY(process_lock_) = 0; // in seconds
// |end_time_| is the time to stop playing based on the context's timeline (0
// or a time less than the context's current time means "now"). If it hasn't
// been set explicitly, then the sound will not stop playing (if looping) or
// will stop when the end of the AudioBuffer has been reached.
double end_time_ GUARDED_BY(process_lock_); // in seconds
// Magic value indicating that the time (start or end) has not yet been set.
static constexpr double kUnknownTime = -1.0;
// Number of extra frames to use when determining if a source node can be
// stopped. This should be at least one rendering quantum, but we add one
// more quantum for good measure. This doesn't need to be extra precise, just
// more than one rendering quantum. See `HandleStoppableSourceNode()`.
static constexpr int kExtraStopFrames = 256;
private:
virtual base::WeakPtr<AudioScheduledSourceHandler> AsWeakPtr() = 0;
// This is accessed by both the main thread and audio thread. Use the setter
// and getter to protect the access to this.
std::atomic<PlaybackState> playback_state_;
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
// Onended event is pending. Becomes true when the node is started,
// and is false when the onended event is fired.
bool on_ended_notification_pending_ = false;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_SCHEDULED_SOURCE_HANDLER_H_
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