blob: 90caf1756b3d1b6d422cb2c0f0efd9fa66058970 [file] [log] [blame]
// Copyright 2016 The Fuchsia 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 <fuchsia/media/cpp/fidl.h>
#include <fbl/ref_ptr.h>
#include "src/lib/fxl/logging.h"
#include "src/lib/fxl/synchronization/thread_annotations.h"
#include "src/lib/fxl/time/time_delta.h"
#include "src/media/audio/audio_core/audio_output.h"
namespace media::audio {
static constexpr fxl::TimeDelta TRIM_PERIOD = fxl::TimeDelta::FromMilliseconds(10);
class ThrottleOutput : public AudioOutput {
static fbl::RefPtr<AudioOutput> Create(AudioDeviceManager* manager) {
return fbl::AdoptRef<AudioOutput>(new ThrottleOutput(manager));
~ThrottleOutput() override = default;
explicit ThrottleOutput(AudioDeviceManager* manager) : AudioOutput(manager) {}
// AudioOutput Implementation
void OnWakeup() FXL_EXCLUSIVE_LOCKS_REQUIRED(mix_domain_->token()) override {
if (uninitialized_) {
last_sched_time_ = fxl::TimePoint::Now();
UpdatePlugState(true, 0);
uninitialized_ = false;
bool StartMixJob(MixJob* job, fxl::TimePoint process_start) override {
// Compute the next callback time; check whether trimming is falling behind.
last_sched_time_ = last_sched_time_ + TRIM_PERIOD;
if (process_start > last_sched_time_) {
// TODO(mpuryear): Trimming is falling behind. We should tell someone.
last_sched_time_ = process_start + TRIM_PERIOD;
// TODO(mpuryear): Optimize the trim operation by scheduling callbacks for
// when our first pending packet ends, rather than polling . This will also
// tighten our timing in returning packets (currently, we hold packets up to
// [TRIM_PERIOD-episilon] past their end PTS before releasing).
// To do this, we would need wake and recompute, whenever an AudioRenderer
// client changes its rate transformation. For now, just polling is simpler.
// Throttle outputs don't actually mix; they provide backpressure to the
// pipeline by holding AudioPacket references until they are presented. We
// only need to schedule our next callback to keep things running, and let
// the base class implementation handle trimming the output.
return false;
bool FinishMixJob(const MixJob& job) override {
// Since we never start any jobs, this should never be called.
return false;
// AudioDevice implementation.
// No one should ever be trying to apply gain limits for a throttle output.
void ApplyGainLimits(fuchsia::media::AudioGainInfo* in_out_info, uint32_t set_flags) override {
fxl::TimePoint last_sched_time_;
bool uninitialized_ = true;
} // namespace media::audio