Unit Test For VCMReceiver::FrameForDecoding Timing Test

webrtc/modules/video_coding/main/source/receiver_unittest.cc

 /*  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include <string.h>
 
 #include <list>
+#include <queue>
 
 #include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/base/checks.h"
 #include "webrtc/modules/video_coding/main/source/packet.h"
 #include "webrtc/modules/video_coding/main/source/receiver.h"
 #include "webrtc/modules/video_coding/main/source/test/stream_generator.h"
 #include "webrtc/modules/video_coding/main/source/timing.h"
 #include "webrtc/modules/video_coding/main/test/test_util.h"
 #include "webrtc/system_wrappers/interface/clock.h"
 #include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
 
 namespace webrtc {
 
 class TestVCMReceiver : public ::testing::Test {
  protected:
   enum { kWidth = 640 };
   enum { kHeight = 480 };
 
   TestVCMReceiver()
       : clock_(new SimulatedClock(0)),
         timing_(clock_.get()),
         receiver_(&timing_, clock_.get(), &event_factory_) {
-    stream_generator_.reset(
-        new StreamGenerator(0, clock_->TimeInMilliseconds()));
+
+    stream_generator_.reset(new
+        StreamGenerator(0, clock_->TimeInMilliseconds()));
   }
 
   virtual void SetUp() {
     receiver_.Reset();
   }
 
   int32_t InsertPacket(int index) {
     VCMPacket packet;
     bool packet_available = stream_generator_->GetPacket(&packet, index);
     EXPECT_TRUE(packet_available);
@@ skipping 261 matching lines @@
   // Advance time until it's time to decode the key frame.
   clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
       key_frame_inserted);
   EXPECT_TRUE(DecodeNextFrame());
   // Make sure we don't get a key frame request since we have a key frame
   // in the list.
   bool request_key_frame = false;
   std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
   EXPECT_FALSE(request_key_frame);
 }
+
+// A simulated clock, when time elapses, will insert frames into the jitter
+// buffer, based on initial settings.
+class SimulatedClockWithFrames : public SimulatedClock {
+ public:
+  SimulatedClockWithFrames(StreamGenerator* stream_generator,
+                           VCMReceiver* receiver)
+      : SimulatedClock(0),
+        stream_generator_(stream_generator),
+        receiver_(receiver) {}
+  virtual ~SimulatedClockWithFrames() {}
+
+  // If |stop_on_frame| is true and next frame arrives between now and
+  // now+|milliseconds|, the clock will be advanced to the arrival time of next
+  // frame.
+  // Otherwise, the clock will be advanced by |milliseconds|.
+  //
+  // For both cases, a frame will be inserted into the jitter buffer at the
+  // instant when the clock time is timestamps_.front().arrive_time.
+  //
+  // Return true if some frame arrives between now and now+|milliseconds|.
+  bool AdvanceTimeMilliseconds(int64_t milliseconds, bool stop_on_frame) {
+    return AdvanceTimeMicroseconds(milliseconds * 1000, stop_on_frame);
+  };
+
+  bool AdvanceTimeMicroseconds(int64_t microseconds, bool stop_on_frame) {
+    int64_t start_time = TimeInMicroseconds();
+    int64_t end_time = start_time + microseconds;
+    bool frame_injected = false;
+    while (!timestamps_.empty() &&
+           timestamps_.front().arrive_time <= end_time) {
+      DCHECK(timestamps_.front().arrive_time >= start_time);
+
+      SimulatedClock::AdvanceTimeMicroseconds(timestamps_.front().arrive_time -
+                                              TimeInMicroseconds());
+      GenerateAndInsertFrame((timestamps_.front().render_time + 500) / 1000);
+      timestamps_.pop();
+      frame_injected = true;
+
+      if (stop_on_frame)
+        return frame_injected;
+    }
+
+    if (TimeInMicroseconds() < end_time) {
+      SimulatedClock::AdvanceTimeMicroseconds(end_time - TimeInMicroseconds());
+    }
+    return frame_injected;
+  };
+
+  // Input timestamps are in unit Milliseconds.
+  // And |arrive_timestamps| must be positive and in increasing order.
+  // |arrive_timestamps| determine when we are going to insert frames into the
+  // jitter buffer.
+  // |render_timestamps| are the timestamps on the frame.
+  void SetFrames(const int64_t* arrive_timestamps,
+                 const int64_t* render_timestamps,
+                 size_t size) {
+    int64_t previous_arrive_timestamp = 0;
+    for (size_t i = 0; i < size; i++) {
+      CHECK(arrive_timestamps[i] >= previous_arrive_timestamp);
+      timestamps_.push(TimestampPair(arrive_timestamps[i] * 1000,
+                                     render_timestamps[i] * 1000));
+      previous_arrive_timestamp = arrive_timestamps[i];
+    }
+  }
+
+ private:
+  struct TimestampPair {
+    TimestampPair(int64_t arrive_timestamp, int64_t render_timestamp)
+        : arrive_time(arrive_timestamp), render_time(render_timestamp) {}
+
+    int64_t arrive_time;
+    int64_t render_time;
+  };
+
+  void GenerateAndInsertFrame(int64_t render_timestamp_ms) {
+    VCMPacket packet;
+    stream_generator_->GenerateFrame(FrameType::kVideoFrameKey,
+                                     1,  // media packets
+                                     0,  // empty packets
+                                     render_timestamp_ms);
+
+    bool packet_available = stream_generator_->PopPacket(&packet, 0);
+    EXPECT_TRUE(packet_available);
+    if (!packet_available)
+      return;  // Return here to avoid crashes below.
+    receiver_->InsertPacket(packet, 640, 480);
+  }
+
+  std::queue<TimestampPair> timestamps_;
+  StreamGenerator* stream_generator_;
+  VCMReceiver* receiver_;
+};
+
+// Use a SimulatedClockWithFrames
+// Wait call will do either of these:
+// 1. If |stop_on_frame| is true, the clock will be turned to the exact instant
+// that the first frame comes and the frame will be inserted into the jitter
+// buffer, or the clock will be turned to now + |max_time| if no frame comes in
+// the window.
+// 2. If |stop_on_frame| is false, the clock will be turn to now + |max_time|,
+// and all the frames arriving between now and now + |max_time| will be
+// inserted into the jitter buffer.
+//
+// This is used to simulate the JitterBuffer getting packets from internet as
+// time elapses.
+
+class FrameInjectEvent : public EventWrapper {
+ public:
+  FrameInjectEvent(SimulatedClockWithFrames* clock, bool stop_on_frame)
+      : clock_(clock), stop_on_frame_(stop_on_frame) {}
+
+  bool Set() override { return true; }
+
+  EventTypeWrapper Wait(unsigned long max_time) override {
+    if (clock_->AdvanceTimeMilliseconds(max_time, stop_on_frame_) &&
+        stop_on_frame_) {
+      return EventTypeWrapper::kEventSignaled;
+    } else {
+      return EventTypeWrapper::kEventTimeout;
+    }
+  }
+
+ private:
+  SimulatedClockWithFrames* clock_;
+  bool stop_on_frame_;
+};
+
+class VCMReceiverTimingTest : public ::testing::Test {
+ protected:
+
+  VCMReceiverTimingTest()
+
+      : clock_(&stream_generator_, &receiver_),
+        stream_generator_(0, clock_.TimeInMilliseconds()),
+        timing_(&clock_),
+        receiver_(
+            &timing_,
+            &clock_,
+            rtc::scoped_ptr<EventWrapper>(new FrameInjectEvent(&clock_, false)),
+            rtc::scoped_ptr<EventWrapper>(
+                new FrameInjectEvent(&clock_, true))) {}
+
+
+  virtual void SetUp() { receiver_.Reset(); }
+
+  SimulatedClockWithFrames clock_;
+  StreamGenerator stream_generator_;
+  VCMTiming timing_;
+  VCMReceiver receiver_;
+};
+
+// Test whether VCMReceiver::FrameForDecoding handles parameter
+// |max_wait_time_ms| correctly:
+// 1. The function execution should never take more than |max_wait_time_ms|.
+// 2. If the function exit before now + |max_wait_time_ms|, a frame must be
+//    returned.
+TEST_F(VCMReceiverTimingTest, FrameForDecoding) {
+  const size_t kNumFrames = 100;
+  const int kFramePeriod = 40;
+  int64_t arrive_timestamps[kNumFrames];
+  int64_t render_timestamps[kNumFrames];
+  int64_t next_render_time;
+
+  // Construct test samples.
+  // render_timestamps are the timestamps stored in the Frame;
+  // arrive_timestamps controls when the Frame packet got received.
+  for (size_t i = 0; i < kNumFrames; i++) {
+    // Preset frame rate to 25Hz.
+    // But we add a reasonable deviation to arrive_timestamps to mimic Internet
+    // fluctuation.
+    arrive_timestamps[i] =
+        (i + 1) * kFramePeriod + (i % 10) * ((i % 2) ? 1 : -1);
+    render_timestamps[i] = (i + 1) * kFramePeriod;
+  }
+
+  clock_.SetFrames(arrive_timestamps, render_timestamps, kNumFrames);
+
+  // Record how many frames we finally get out of the receiver.
+  size_t num_frames_return = 0;
+
+  const int64_t kMaxWaitTime = 30;
+
+  // Ideally, we should get all frames that we input in InitializeFrames.
+  // In the case that FrameForDecoding kills frames by error, we rely on the
+  // build bot to kill the test.
+  while (num_frames_return < kNumFrames) {
+    int64_t start_time = clock_.TimeInMilliseconds();
+    VCMEncodedFrame* frame =
+        receiver_.FrameForDecoding(kMaxWaitTime, next_render_time, false);
+    int64_t end_time = clock_.TimeInMilliseconds();
+
+    // In any case the FrameForDecoding should not wait longer than
+    // max_wait_time.
+    // In the case that we did not get a frame, it should have been waiting for
+    // exactly max_wait_time. (By the testing samples we constructed above, we
+    // are sure there is no timing error, so the only case it returns with NULL
+    // is that it runs out of time.)
+    if (frame) {
+      receiver_.ReleaseFrame(frame);
+      ++num_frames_return;
+      EXPECT_GE(kMaxWaitTime, end_time - start_time);
+    } else {
+      EXPECT_EQ(kMaxWaitTime, end_time - start_time);
+    }
+  }
+}
+
 }  // namespace webrtc