| // 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 |
| |