Deliver video frames on Android, on the decode thread.

webrtc/modules/video_coding/video_receiver.cc

Index: webrtc/modules/video_coding/video_receiver.cc
diff --git a/webrtc/modules/video_coding/video_receiver.cc b/webrtc/modules/video_coding/video_receiver.cc
index 84f5af521f6a8e9970e628b6e905da6efd53db73..f1503ba89e2aab7359fbb1fd225893ace3f65729 100644
--- a/webrtc/modules/video_coding/video_receiver.cc
+++ b/webrtc/modules/video_coding/video_receiver.cc
@@ -9,12 +9,14 @@
  */
 
 #include "webrtc/base/checks.h"
+#include "webrtc/base/location.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/trace_event.h"
 #include "webrtc/common_types.h"
 #include "webrtc/common_video/libyuv/include/webrtc_libyuv.h"
-#include "webrtc/modules/video_coding/include/video_codec_interface.h"
+#include "webrtc/modules/utility/include/process_thread.h"
 #include "webrtc/modules/video_coding/encoded_frame.h"
+#include "webrtc/modules/video_coding/include/video_codec_interface.h"
 #include "webrtc/modules/video_coding/jitter_buffer.h"
 #include "webrtc/modules/video_coding/packet.h"
 #include "webrtc/modules/video_coding/video_coding_impl.h"
@@ -40,7 +42,6 @@ VideoReceiver::VideoReceiver(Clock* clock,
       _frameTypeCallback(nullptr),
       _receiveStatsCallback(nullptr),
       _packetRequestCallback(nullptr),
-      _frameFromFile(),
       _scheduleKeyRequest(false),
       drop_frames_until_keyframe_(false),
       max_nack_list_size_(0),
@@ -48,18 +49,23 @@ VideoReceiver::VideoReceiver(Clock* clock,
       pre_decode_image_callback_(pre_decode_image_callback),
       _receiveStatsTimer(1000, clock_),
       _retransmissionTimer(10, clock_),
-      _keyRequestTimer(500, clock_) {}
+      _keyRequestTimer(500, clock_) {
+  decoder_thread_.DetachFromThread();
+  module_thread_.DetachFromThread();
+}
 
-VideoReceiver::~VideoReceiver() {}
+VideoReceiver::~VideoReceiver() {
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+}
 
 void VideoReceiver::Process() {
+  RTC_DCHECK_RUN_ON(&module_thread_);
   // Receive-side statistics
 
   // TODO(philipel): Remove this if block when we know what to do with
   //                 ReceiveStatisticsProxy::QualitySample.
   if (_receiveStatsTimer.TimeUntilProcess() == 0) {
     _receiveStatsTimer.Processed();
-    rtc::CritScope cs(&process_crit_);
     if (_receiveStatsCallback != nullptr) {
       _receiveStatsCallback->OnReceiveRatesUpdated(0, 0);
     }
@@ -68,10 +74,10 @@ void VideoReceiver::Process() {
   // Key frame requests
   if (_keyRequestTimer.TimeUntilProcess() == 0) {
     _keyRequestTimer.Processed();
-    bool request_key_frame = false;
-    {
+    bool request_key_frame = _frameTypeCallback != nullptr;
+    if (request_key_frame) {
       rtc::CritScope cs(&process_crit_);
-      request_key_frame = _scheduleKeyRequest && _frameTypeCallback != nullptr;
+      request_key_frame = _scheduleKeyRequest;
     }
     if (request_key_frame)
       RequestKeyFrame();
@@ -82,13 +88,8 @@ void VideoReceiver::Process() {
   // disabled when NACK is off.
   if (_retransmissionTimer.TimeUntilProcess() == 0) {
     _retransmissionTimer.Processed();
-    bool callback_registered = false;
-    uint16_t length;
-    {
-      rtc::CritScope cs(&process_crit_);
-      length = max_nack_list_size_;
-      callback_registered = _packetRequestCallback != nullptr;
-    }
+    bool callback_registered = _packetRequestCallback != nullptr;
+    uint16_t length = max_nack_list_size_;
     if (callback_registered && length > 0) {
       // Collect sequence numbers from the default receiver.
       bool request_key_frame = false;
@@ -98,7 +99,6 @@ void VideoReceiver::Process() {
         ret = RequestKeyFrame();
       }
       if (ret == VCM_OK && !nackList.empty()) {
-        rtc::CritScope cs(&process_crit_);
         if (_packetRequestCallback != nullptr) {
           _packetRequestCallback->ResendPackets(&nackList[0], nackList.size());
         }
@@ -107,7 +107,18 @@ void VideoReceiver::Process() {
   }
 }
 
+void VideoReceiver::ProcessThreadAttached(ProcessThread* process_thread) {
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  if (process_thread) {
+    is_attached_to_process_thread_ = true;
+    process_thread_ = process_thread;
+  } else {
+    is_attached_to_process_thread_ = false;
+  }
+}
+
 int64_t VideoReceiver::TimeUntilNextProcess() {
+  RTC_DCHECK_RUN_ON(&module_thread_);
   int64_t timeUntilNextProcess = _receiveStatsTimer.TimeUntilProcess();
   if (_receiver.NackMode() != kNoNack) {
     // We need a Process call more often if we are relying on
@@ -122,7 +133,7 @@ int64_t VideoReceiver::TimeUntilNextProcess() {
 }
 
 int32_t VideoReceiver::SetReceiveChannelParameters(int64_t rtt) {
-  rtc::CritScope cs(&receive_crit_);
+  RTC_DCHECK_RUN_ON(&module_thread_);
   _receiver.UpdateRtt(rtt);
   return 0;
 }
@@ -142,7 +153,6 @@ int32_t VideoReceiver::SetVideoProtection(VCMVideoProtection videoProtection,
     }
 
     case kProtectionNackFEC: {
-      rtc::CritScope cs(&receive_crit_);
       RTC_DCHECK(enable);
       _receiver.SetNackMode(kNack,
                             media_optimization::kLowRttNackMs,
@@ -165,20 +175,22 @@ int32_t VideoReceiver::SetVideoProtection(VCMVideoProtection videoProtection,
 // ready for rendering.
 int32_t VideoReceiver::RegisterReceiveCallback(
     VCMReceiveCallback* receiveCallback) {
-  RTC_DCHECK(construction_thread_.CalledOnValidThread());
-  // TODO(tommi): Callback may be null, but only after the decoder thread has
-  // been stopped. Use the signal we now get that tells us when the decoder
-  // thread isn't running, to DCHECK that the method is never called while it
-  // is. Once we're confident, we can remove the lock.
-  rtc::CritScope cs(&receive_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
+  // This value is set before the decoder thread starts and unset after
+  // the decoder thread has been stopped.
   _decodedFrameCallback.SetUserReceiveCallback(receiveCallback);
   return VCM_OK;
 }
 
 int32_t VideoReceiver::RegisterReceiveStatisticsCallback(
     VCMReceiveStatisticsCallback* receiveStats) {
-  RTC_DCHECK(construction_thread_.CalledOnValidThread());
-  rtc::CritScope cs(&process_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
+  // |_receiver| is used on both the decoder and module threads.
+  // However, since we make sure that we never do anything on the module thread
+  // when the decoder thread is not running, we don't need a lock for the
+  // |_receiver| or |_receiveStatsCallback| here.
   _receiver.RegisterStatsCallback(receiveStats);
   _receiveStatsCallback = receiveStats;
   return VCM_OK;
@@ -187,10 +199,8 @@ int32_t VideoReceiver::RegisterReceiveStatisticsCallback(
 // Register an externally defined decoder object.
 void VideoReceiver::RegisterExternalDecoder(VideoDecoder* externalDecoder,
                                             uint8_t payloadType) {
-  RTC_DCHECK(construction_thread_.CalledOnValidThread());
-  // TODO(tommi): This method must be called when the decoder thread is not
-  // running.  Do we need a lock in that case?
-  rtc::CritScope cs(&receive_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
   if (externalDecoder == nullptr) {
     RTC_CHECK(_codecDataBase.DeregisterExternalDecoder(payloadType));
     return;
@@ -201,53 +211,87 @@ void VideoReceiver::RegisterExternalDecoder(VideoDecoder* externalDecoder,
 // Register a frame type request callback.
 int32_t VideoReceiver::RegisterFrameTypeCallback(
     VCMFrameTypeCallback* frameTypeCallback) {
-  rtc::CritScope cs(&process_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
+  // This callback is used on the module thread, but since we don't get
+  // callbacks on the module thread while the decoder thread isn't running
+  // (and this function must not be called when the decoder is running),
+  // we don't need a lock here.
   _frameTypeCallback = frameTypeCallback;
   return VCM_OK;
 }
 
 int32_t VideoReceiver::RegisterPacketRequestCallback(
     VCMPacketRequestCallback* callback) {
-  rtc::CritScope cs(&process_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
+  // This callback is used on the module thread, but since we don't get
+  // callbacks on the module thread while the decoder thread isn't running
+  // (and this function must not be called when the decoder is running),
+  // we don't need a lock here.
   _packetRequestCallback = callback;
   return VCM_OK;
 }
 
 void VideoReceiver::TriggerDecoderShutdown() {
-  RTC_DCHECK(construction_thread_.CalledOnValidThread());
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(IsDecoderThreadRunning());
   _receiver.TriggerDecoderShutdown();
 }
 
+void VideoReceiver::DecoderThreadStarting() {
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
+  if (process_thread_ && !is_attached_to_process_thread_) {
+    process_thread_->RegisterModule(this, RTC_FROM_HERE);
+  }
+#if RTC_DCHECK_IS_ON
+  decoder_thread_is_running_ = true;
+#endif
+}
+
+void VideoReceiver::DecoderThreadStopped() {
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(IsDecoderThreadRunning());
+  if (process_thread_ && is_attached_to_process_thread_) {
+    process_thread_->DeRegisterModule(this);
+  }
+#if RTC_DCHECK_IS_ON
+  decoder_thread_is_running_ = false;
+  decoder_thread_.DetachFromThread();
+#endif
+}
+
 // Decode next frame, blocking.
 // Should be called as often as possible to get the most out of the decoder.
 int32_t VideoReceiver::Decode(uint16_t maxWaitTimeMs) {
-  bool prefer_late_decoding = false;
-  {
-    // TODO(tommi): Chances are that this lock isn't required.
-    rtc::CritScope cs(&receive_crit_);
-    prefer_late_decoding = _codecDataBase.PrefersLateDecoding();
-  }
-
-  VCMEncodedFrame* frame =
-      _receiver.FrameForDecoding(maxWaitTimeMs, prefer_late_decoding);
+  RTC_DCHECK_RUN_ON(&decoder_thread_);
+  VCMEncodedFrame* frame = _receiver.FrameForDecoding(
+      maxWaitTimeMs, _codecDataBase.PrefersLateDecoding());
 
   if (!frame)
     return VCM_FRAME_NOT_READY;
 
+  bool drop_frame = false;
   {
     rtc::CritScope cs(&process_crit_);
     if (drop_frames_until_keyframe_) {
       // Still getting delta frames, schedule another keyframe request as if
       // decode failed.
       if (frame->FrameType() != kVideoFrameKey) {
+        drop_frame = true;
         _scheduleKeyRequest = true;
-        _receiver.ReleaseFrame(frame);
-        return VCM_FRAME_NOT_READY;
+      } else {
+        drop_frames_until_keyframe_ = false;
       }
-      drop_frames_until_keyframe_ = false;
     }
   }
 
+  if (drop_frame) {
+    _receiver.ReleaseFrame(frame);
+    return VCM_FRAME_NOT_READY;
+  }
+
   if (pre_decode_image_callback_) {
     EncodedImage encoded_image(frame->EncodedImage());
     int qp = -1;
@@ -258,7 +302,6 @@ int32_t VideoReceiver::Decode(uint16_t maxWaitTimeMs) {
                                                frame->CodecSpecific(), nullptr);
   }
 
-  rtc::CritScope cs(&receive_crit_);
   // If this frame was too late, we should adjust the delay accordingly
   _timing->UpdateCurrentDelay(frame->RenderTimeMs(),
                               clock_->TimeInMilliseconds());
@@ -278,7 +321,7 @@ int32_t VideoReceiver::Decode(uint16_t maxWaitTimeMs) {
 // TODO(philipel): Clean up among the Decode functions as we replace
 //                 VCMEncodedFrame with FrameObject.
 int32_t VideoReceiver::Decode(const webrtc::VCMEncodedFrame* frame) {
-  rtc::CritScope lock(&receive_crit_);
+  RTC_DCHECK_RUN_ON(&decoder_thread_);
   if (pre_decode_image_callback_) {
     EncodedImage encoded_image(frame->EncodedImage());
     int qp = -1;
@@ -291,19 +334,20 @@ int32_t VideoReceiver::Decode(const webrtc::VCMEncodedFrame* frame) {
   return Decode(*frame);
 }
 
-void VideoReceiver::DecodingStopped() {
-  // No further calls to Decode() will be made after this point.
-  // TODO(tommi): Make use of this to clarify and check threading model.
-}
-
 int32_t VideoReceiver::RequestKeyFrame() {
+  RTC_DCHECK_RUN_ON(&module_thread_);
+
+  // Since we deregister from the module thread when the decoder thread isn't
+  // running, we should get no calls here if decoding isn't being done.
+  RTC_DCHECK(IsDecoderThreadRunning());
+
   TRACE_EVENT0("webrtc", "RequestKeyFrame");
-  rtc::CritScope cs(&process_crit_);
   if (_frameTypeCallback != nullptr) {
     const int32_t ret = _frameTypeCallback->RequestKeyFrame();
     if (ret < 0) {
       return ret;
     }
+    rtc::CritScope cs(&process_crit_);
     _scheduleKeyRequest = false;
   } else {
     return VCM_MISSING_CALLBACK;
@@ -313,6 +357,7 @@ int32_t VideoReceiver::RequestKeyFrame() {
 
 // Must be called from inside the receive side critical section.
 int32_t VideoReceiver::Decode(const VCMEncodedFrame& frame) {
+  RTC_DCHECK_RUN_ON(&decoder_thread_);
   TRACE_EVENT0("webrtc", "VideoReceiver::Decode");
   // Change decoder if payload type has changed
   VCMGenericDecoder* decoder =
@@ -324,31 +369,41 @@ int32_t VideoReceiver::Decode(const VCMEncodedFrame& frame) {
   int32_t ret = decoder->Decode(frame, clock_->TimeInMilliseconds());
 
   // Check for failed decoding, run frame type request callback if needed.
-  bool request_key_frame = false;
-  if (ret < 0) {
-    request_key_frame = true;
-  }
+  bool request_key_frame = (ret < 0);
 
   if (!frame.Complete() || frame.MissingFrame()) {
     request_key_frame = true;
     ret = VCM_OK;
   }
+
   if (request_key_frame) {
     rtc::CritScope cs(&process_crit_);
-    _scheduleKeyRequest = true;
+    if (!_scheduleKeyRequest) {
+      _scheduleKeyRequest = true;
+      // TODO(tommi): Consider if we could instead post a task to the module
+      // thread and call RequestKeyFrame directly. Here we call WakeUp so that
+      // TimeUntilNextProcess() gets called straight away.
+      process_thread_->WakeUp(this);
+    }
   }
   return ret;
 }
 
+#if defined(WEBRTC_ANDROID)
+void VideoReceiver::PollDecodedFrames() {
+  RTC_DCHECK_RUN_ON(&decoder_thread_);
+  auto* current_decoder = _codecDataBase.GetCurrentDecoder();
+  if (current_decoder)
+    current_decoder->PollDecodedFrames();
+}
+#endif
+
 // Register possible receive codecs, can be called multiple times
 int32_t VideoReceiver::RegisterReceiveCodec(const VideoCodec* receiveCodec,
                                             int32_t numberOfCores,
                                             bool requireKeyFrame) {
-  RTC_DCHECK(construction_thread_.CalledOnValidThread());
-  // TODO(tommi): This method must only be called when the decoder thread
-  // is not running. Do we need a lock? If not, it looks like we might not need
-  // a lock at all for |_codecDataBase|.
-  rtc::CritScope cs(&receive_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
   if (receiveCodec == nullptr) {
     return VCM_PARAMETER_ERROR;
   }
@@ -363,6 +418,7 @@ int32_t VideoReceiver::RegisterReceiveCodec(const VideoCodec* receiveCodec,
 int32_t VideoReceiver::IncomingPacket(const uint8_t* incomingPayload,
                                       size_t payloadLength,
                                       const WebRtcRTPHeader& rtpInfo) {
+  RTC_DCHECK_RUN_ON(&module_thread_);
   if (rtpInfo.frameType == kVideoFrameKey) {
     TRACE_EVENT1("webrtc", "VCM::PacketKeyFrame", "seqnum",
                  rtpInfo.header.sequenceNumber);
@@ -394,6 +450,7 @@ int32_t VideoReceiver::IncomingPacket(const uint8_t* incomingPayload,
 // to sync with audio. Not included in  VideoCodingModule::Delay()
 // Defaults to 0 ms.
 int32_t VideoReceiver::SetMinimumPlayoutDelay(uint32_t minPlayoutDelayMs) {
+  RTC_DCHECK_RUN_ON(&module_thread_);
   _timing->set_min_playout_delay(minPlayoutDelayMs);
   return VCM_OK;
 }
@@ -401,22 +458,24 @@ int32_t VideoReceiver::SetMinimumPlayoutDelay(uint32_t minPlayoutDelayMs) {
 // The estimated delay caused by rendering, defaults to
 // kDefaultRenderDelayMs = 10 ms
 int32_t VideoReceiver::SetRenderDelay(uint32_t timeMS) {
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
   _timing->set_render_delay(timeMS);
   return VCM_OK;
 }
 
 // Current video delay
 int32_t VideoReceiver::Delay() const {
+  RTC_DCHECK_RUN_ON(&module_thread_);
   return _timing->TargetVideoDelay();
 }
 
+// Only used by VCMRobustnessTest.
 int VideoReceiver::SetReceiverRobustnessMode(
     VideoCodingModule::ReceiverRobustness robustnessMode,
     VCMDecodeErrorMode decode_error_mode) {
-  RTC_DCHECK(construction_thread_.CalledOnValidThread());
-  // TODO(tommi): This method must only be called when the decoder thread
-  // is not running and we don't need to hold this lock.
-  rtc::CritScope cs(&receive_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
   switch (robustnessMode) {
     case VideoCodingModule::kNone:
       _receiver.SetNackMode(kNoNack, -1, -1);
@@ -434,24 +493,40 @@ int VideoReceiver::SetReceiverRobustnessMode(
 }
 
 void VideoReceiver::SetDecodeErrorMode(VCMDecodeErrorMode decode_error_mode) {
-  rtc::CritScope cs(&receive_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
   _receiver.SetDecodeErrorMode(decode_error_mode);
 }
 
 void VideoReceiver::SetNackSettings(size_t max_nack_list_size,
                                     int max_packet_age_to_nack,
                                     int max_incomplete_time_ms) {
-  if (max_nack_list_size != 0) {
-    rtc::CritScope cs(&process_crit_);
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
+
+  if (max_nack_list_size != 0)
     max_nack_list_size_ = max_nack_list_size;
-  }
   _receiver.SetNackSettings(max_nack_list_size, max_packet_age_to_nack,
                             max_incomplete_time_ms);
 }
 
 int VideoReceiver::SetMinReceiverDelay(int desired_delay_ms) {
+  RTC_DCHECK_RUN_ON(&construction_thread_);
+  RTC_DCHECK(!IsDecoderThreadRunning());
+  // TODO(tommi): Is the method only used by tests? Maybe could be offered
+  // via a test only subclass?
+  // Info from Stefan: If it is indeed only used by tests I think it's just that
+  // it hasn't been cleaned up when the calling code was cleaned up.
   return _receiver.SetMinReceiverDelay(desired_delay_ms);
 }
 
+bool VideoReceiver::IsDecoderThreadRunning() {
+#if RTC_DCHECK_IS_ON
+  return decoder_thread_is_running_;
+#else
+  return true;
+#endif
+}
+
 }  // namespace vcm
 }  // namespace webrtc