[Chromecast] Make ALSA rendering delay either accurate or kNoTimestamp

chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.cc

 // 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 "chromecast/media/cma/backend/alsa/stream_mixer_alsa_input_impl.h"
 
 #include <algorithm>
+#include <limits>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chromecast/media/cma/backend/alsa/stream_mixer_alsa.h"
 #include "chromecast/media/cma/base/decoder_buffer_base.h"
@@ skipping 28 matching lines @@
 namespace {
 
 const int kNumOutputChannels = 2;
 const int64_t kMaxInputQueueUs = 90000;
 const int64_t kFadeMs = 15;
 // Number of samples to report as readable when paused. When paused, the mixer
 // will still pull this many frames each time it tries to write frames, but we
 // fill the frames with silence.
 const int kPausedReadSamples = 512;
 const int kDefaultReadSize = ::media::SincResampler::kDefaultRequestSize;
+const int64_t kNoTimestamp = std::numeric_limits<int64_t>::min();
 
 }  // namespace
 
 StreamMixerAlsaInputImpl::StreamMixerAlsaInputImpl(
     StreamMixerAlsaInput::Delegate* delegate,
     int input_samples_per_second,
     bool primary,
     StreamMixerAlsa* mixer)
     : delegate_(delegate),
       input_samples_per_second_(input_samples_per_second),
@@ skipping 127 matching lines @@
     const scoped_refptr<DecoderBufferBase>& data) {
   queue_lock_.AssertAcquired();
   if (!data->end_of_stream()) {
     int frames = data->data_size() / (kNumOutputChannels * sizeof(float));
     queue_.push_back(data);
     queued_frames_ += frames;
     queued_frames_including_resampler_ += frames;
   }
 
   MediaPipelineBackendAlsa::RenderingDelay delay = mixer_rendering_delay_;
-  delay.delay_microseconds += static_cast<int64_t>(
-      queued_frames_including_resampler_ * base::Time::kMicrosecondsPerSecond /
-      input_samples_per_second_);
+  if (delay.timestamp_microseconds != kNoTimestamp) {
+    delay.delay_microseconds += static_cast<int64_t>(
+        queued_frames_including_resampler_ *
+        base::Time::kMicrosecondsPerSecond / input_samples_per_second_);
+  }
   return delay;
 }
 
 void StreamMixerAlsaInputImpl::PostPcmCallback(
     const MediaPipelineBackendAlsa::RenderingDelay& delay) {
   RUN_ON_CALLER_THREAD(PostPcmCallback, delay);
   delegate_->OnWritePcmCompletion(MediaPipelineBackendAlsa::kBufferSuccess,
                                   delay);
 }
 
@@ skipping 268 matching lines @@
   DCHECK(!IsDeleting());
   if (multiplier > 1.0f)
     multiplier = 1.0f;
   if (multiplier < 0.0f)
     multiplier = 0.0f;
   volume_multiplier_ = multiplier;
 }
 
 }  // namespace media
 }  // namespace chromecast