blob: 47489a0f2038e38213e3e1f4566abe11525d727f [file] [log] [blame]
// Copyright 2015 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 "base/bind.h"
#include "base/callback.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/time/time.h"
#include "mojo/services/media/common/cpp/local_time.h"
#include "services/media/audio/audio_output_manager.h"
#include "services/media/audio/platform/generic/throttle_output.h"
namespace mojo {
namespace media {
namespace audio {
static constexpr LocalDuration TRIM_PERIOD = local_time::from_msec(10);
ThrottleOutput::ThrottleOutput(AudioOutputManager* manager)
: StandardOutputBase(manager) {}
ThrottleOutput::~ThrottleOutput() {}
AudioOutputPtr ThrottleOutput::New(AudioOutputManager* manager) {
return AudioOutputPtr(new ThrottleOutput(manager));
}
MediaResult ThrottleOutput::Init() {
last_sched_time_ = LocalClock::now();
return MediaResult::OK;
}
bool ThrottleOutput::StartMixJob(MixJob* job,
const LocalTime& process_start) {
// Compute our next callback time, and check to see if we are falling behind
// in the process.
last_sched_time_ += TRIM_PERIOD;
if (process_start > last_sched_time_) {
// TODO(johngro): We are falling behind on our trimming. We should
// probably tell someone.
last_sched_time_ = process_start + TRIM_PERIOD;;
}
// TODO(johngro): We could optimize this trim operation by scheduling our
// callback to the time at which the first pending packet in our queue will
// end, instead of using this polling style. This would have the addition
// benefit of tighten the timing on returning packets (currently, we could
// hold a packet for up to TRIM_PERIOD - episilon past its end pts before
// releasing it)
//
// In order to do this, however, we would to wake up and recompute whenever
// the rate transformations for one of our client tracks changes. For now, we
// just poll because its simpler.
SetNextSchedTime(last_sched_time_);
// The throttle output never actually mixes anything, it just provides
// backpressure to the pipeline by holding references to AudioPackets until
// after their presentation should be finished. All we need to do here is
// schedule our next callback to keep things running, and let the base class
// implementation handle trimming the output.
return false;
}
bool ThrottleOutput::FinishMixJob(const MixJob& job) {
// Since we never start any jobs, this should never be called.
DCHECK(false);
return false;
}
} // namespace audio
} // namespace media
} // namespace mojo