Reducing the IPC latency for MSE video decoding

media/base/android/media_source_player.cc

Index: media/base/android/media_source_player.cc
diff --git a/media/base/android/media_source_player.cc b/media/base/android/media_source_player.cc
index 584d50b2385167d44046b41bfb0c8b139c3279e6..cb63e1c31142def843b2198aa9d713f64fc848a8 100644
--- a/media/base/android/media_source_player.cc
+++ b/media/base/android/media_source_player.cc
@@ -61,7 +61,9 @@ MediaSourcePlayer::MediaSourcePlayer(
       reconfig_video_decoder_(false),
       weak_this_(this),
       drm_bridge_(NULL),
-      is_waiting_for_key_(false) {
+      is_waiting_for_key_(false),
+      has_pending_audio_data_request_(false),
+      has_pending_video_data_request_(false) {
   demuxer_->Initialize(this);
   clock_.SetMaxTime(base::TimeDelta());
 }
@@ -106,7 +108,7 @@ void MediaSourcePlayer::SetVideoSurface(gfx::ScopedJavaSurface surface) {
 }
 
 void MediaSourcePlayer::ScheduleSeekEventAndStopDecoding(
-    const base::TimeDelta& seek_time) {
+    base::TimeDelta seek_time) {
   DVLOG(1) << __FUNCTION__ << "(" << seek_time.InSecondsF() << ")";
   DCHECK(!IsEventPending(SEEK_EVENT_PENDING));
 
@@ -177,7 +179,7 @@ int MediaSourcePlayer::GetVideoHeight() {
   return height_;
 }
 
-void MediaSourcePlayer::SeekTo(const base::TimeDelta& timestamp) {
+void MediaSourcePlayer::SeekTo(base::TimeDelta timestamp) {
   DVLOG(1) << __FUNCTION__ << "(" << timestamp.InSecondsF() << ")";
 
   if (IsEventPending(SEEK_EVENT_PENDING)) {
@@ -222,7 +224,7 @@ void MediaSourcePlayer::Release() {
   // Clear all the pending events except seeks and config changes.
   pending_event_ &= (SEEK_EVENT_PENDING | CONFIG_CHANGE_EVENT_PENDING);
   is_surface_in_use_ = false;
-  audio_decoder_job_.reset();
+  ResetAudioDecoderJob();
   ResetVideoDecoderJob();
 
   // Prevent job re-creation attempts in OnDemuxerConfigsAvailable()
@@ -345,8 +347,24 @@ void MediaSourcePlayer::OnDemuxerConfigsAvailable(
 void MediaSourcePlayer::OnDemuxerDataAvailable(const DemuxerData& data) {
   DVLOG(1) << __FUNCTION__ << "(" << data.type << ")";
   DCHECK_LT(0u, data.access_units.size());
+
+  if (has_pending_audio_data_request_ && data.type == DemuxerStream::AUDIO) {
+    has_pending_audio_data_request_ = false;
+    ProcessPendingEvents();
+    return;
+  }
+
+  if (has_pending_video_data_request_ && data.type == DemuxerStream::VIDEO) {
+    next_video_data_is_iframe_ = false;
+    has_pending_video_data_request_ = false;
+    ProcessPendingEvents();
+    return;
+  }
+
   if (data.type == DemuxerStream::AUDIO && audio_decoder_job_) {
     audio_decoder_job_->OnDataReceived(data);
+
+

[wolenetz, 2014/03/18 21:14:47]

nit: remove extra lines (both of these)

[qinmin, 2014/03/19 02:45:22]

Done.

   } else if (data.type == DemuxerStream::VIDEO) {
     next_video_data_is_iframe_ = false;
     if (video_decoder_job_)
@@ -397,7 +415,7 @@ void MediaSourcePlayer::SetDrmBridge(MediaDrmBridge* drm_bridge) {
 }
 
 void MediaSourcePlayer::OnDemuxerSeekDone(
-    const base::TimeDelta& actual_browser_seek_time) {
+    base::TimeDelta actual_browser_seek_time) {
   DVLOG(1) << __FUNCTION__;
 
   ClearPendingEvent(SEEK_EVENT_PENDING);
@@ -418,15 +436,16 @@ void MediaSourcePlayer::OnDemuxerSeekDone(
   // I-frame later than the requested one due to data removal or GC. Update
   // player clock to the actual seek target.
   if (doing_browser_seek_) {
-    DCHECK(actual_browser_seek_time != kNoTimestamp());
+    base::TimeDelta seek_time = (actual_browser_seek_time == kNoTimestamp()) ?

[wolenetz, 2014/03/18 21:14:47]

See also comment in unit tests. Why are we now allowing kNoTimestamp() for
browser seek actual seek time?

[qinmin, 2014/03/19 02:45:22]

I saw the kNoTimestamp() in unit tests and it makes me unsure about what the
chunk demuxer may return. Removed this if we can guarantee there will be no
kNoTimestamp from the demuxer.

On 2014/03/18 21:14:47, wolenetz wrote:

+        base::TimeDelta() : actual_browser_seek_time;
     // A browser seek must not jump into the past. Ideally, it seeks to the
     // requested time, but it might jump into the future.
-    DCHECK(actual_browser_seek_time >= GetCurrentTime());
+    DCHECK(seek_time >= GetCurrentTime());
     DVLOG(1) << __FUNCTION__ << " : setting clock to actual browser seek time: "
-             << actual_browser_seek_time.InSecondsF();
-    clock_.SetTime(actual_browser_seek_time, actual_browser_seek_time);
+             << seek_time.InSecondsF();
+    clock_.SetTime(seek_time, seek_time);
     if (audio_timestamp_helper_)
-      audio_timestamp_helper_->SetBaseTimestamp(actual_browser_seek_time);
+      audio_timestamp_helper_->SetBaseTimestamp(seek_time);
   }
 
   reached_audio_eos_ = false;
@@ -450,7 +469,7 @@ void MediaSourcePlayer::OnDemuxerSeekDone(
 }
 
 void MediaSourcePlayer::UpdateTimestamps(
-    const base::TimeDelta& presentation_timestamp, size_t audio_output_bytes) {
+    base::TimeDelta presentation_timestamp, size_t audio_output_bytes) {
   base::TimeDelta new_max_time = presentation_timestamp;
 
   if (audio_output_bytes > 0) {
@@ -476,6 +495,11 @@ void MediaSourcePlayer::ProcessPendingEvents() {
     return;
   }
 
+  if (has_pending_audio_data_request_ || has_pending_video_data_request_) {
+    DVLOG(1) << __FUNCTION__ << " : has pending data request.";
+    return;
+  }
+
   if (IsEventPending(PREFETCH_DONE_EVENT_PENDING)) {
     DVLOG(1) << __FUNCTION__ << " : PREFETCH_DONE still pending.";
     return;
@@ -510,6 +534,14 @@ void MediaSourcePlayer::ProcessPendingEvents() {
 
   if (IsEventPending(PREFETCH_REQUEST_EVENT_PENDING)) {
     DVLOG(1) << __FUNCTION__ << " : Handling PREFETCH_REQUEST_EVENT.";
+    // If one of the decoder is not initialized, cancel this event as it will be
+    // called later when Start() is called again.
+    if ((HasVideo() && !video_decoder_job_) ||
+        (HasAudio() && !audio_decoder_job_)) {
+      ClearPendingEvent(PREFETCH_REQUEST_EVENT_PENDING);
+      return;
+    }
+
     DCHECK(audio_decoder_job_ || AudioFinished());
     DCHECK(video_decoder_job_ || VideoFinished());
 
@@ -545,7 +577,7 @@ void MediaSourcePlayer::ProcessPendingEvents() {
 
 void MediaSourcePlayer::MediaDecoderCallback(
     bool is_audio, MediaCodecStatus status,
-    const base::TimeDelta& presentation_timestamp, size_t audio_output_bytes) {
+    base::TimeDelta presentation_timestamp, size_t audio_output_bytes) {
   DVLOG(1) << __FUNCTION__ << ": " << is_audio << ", " << status;
 
   // TODO(xhwang): Drop IntToString() when http://crbug.com/303899 is fixed.
@@ -747,7 +779,7 @@ bool MediaSourcePlayer::VideoFinished() {
 
 void MediaSourcePlayer::ConfigureAudioDecoderJob() {
   if (!HasAudio()) {
-    audio_decoder_job_.reset();
+    ResetAudioDecoderJob();
     return;
   }
 
@@ -761,8 +793,8 @@ void MediaSourcePlayer::ConfigureAudioDecoderJob() {
 
   DCHECK(!audio_decoder_job_ || !audio_decoder_job_->is_decoding());
 
+  ResetAudioDecoderJob();
   DVLOG(1) << __FUNCTION__ << " : creating new audio decoder job";
-
   audio_decoder_job_.reset(AudioDecoderJob::Create(
       audio_codec_, sampling_rate_, num_channels_, &audio_extra_data_[0],
       audio_extra_data_.size(), media_crypto.obj(),
@@ -777,6 +809,10 @@ void MediaSourcePlayer::ConfigureAudioDecoderJob() {
 }
 
 void MediaSourcePlayer::ResetVideoDecoderJob() {
+  if (video_decoder_job_) {
+    has_pending_video_data_request_ =
+        video_decoder_job_->is_requesting_demuxer_data();
+  }
   video_decoder_job_.reset();
 
   // Any eventual video decoder job re-creation will use the current |surface_|.
@@ -784,6 +820,14 @@ void MediaSourcePlayer::ResetVideoDecoderJob() {
     ClearPendingEvent(SURFACE_CHANGE_EVENT_PENDING);
 }
 
+void MediaSourcePlayer::ResetAudioDecoderJob() {
+  if (audio_decoder_job_) {
+    has_pending_audio_data_request_ =
+        audio_decoder_job_->is_requesting_demuxer_data();
+  }
+  audio_decoder_job_.reset();
+}
+
 void MediaSourcePlayer::ConfigureVideoDecoderJob() {
   if (!HasVideo() || surface_.IsEmpty()) {
     ResetVideoDecoderJob();
@@ -860,7 +904,7 @@ void MediaSourcePlayer::OnDecoderStarved() {
 }
 
 void MediaSourcePlayer::StartStarvationCallback(
-    const base::TimeDelta& presentation_timestamp) {
+    base::TimeDelta presentation_timestamp) {
   // 20ms was chosen because it is the typical size of a compressed audio frame.
   // Anything smaller than this would likely cause unnecessary cycling in and
   // out of the prefetch state.