vea_unittest: Calculate per-frame encode latency

Calculates per-frame encode latency, which is basically the time delay from
input of each VideoFrame (VEA::Encode()) to output of the corresponding
BitstreamBuffer (VEA::Client::BitstreamBufferReady()).

It calculates encode latency values at the 50th(median), 75th, and 95th percentiles.

Also fix a wrong comment.

BUG=345181
TEST=Check "Encode latency for the 50%/75%/95%" in output logs.

Committed: https://crrev.com/b21ffeee2aff4da8edb9808b2227165c37e5ce86
Cr-Commit-Position: refs/heads/master@{#329819}

Review URL: https://codereview.chromium.org/1117853002

Cr-Commit-Position: refs/heads/master@{#329838}

content/common/gpu/media/video_encode_accelerator_unittest.cc

@@ -2,6 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <inttypes.h>
+
+#include <algorithm>
+
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/command_line.h"
@@ -70,6 +74,8 @@ const uint32 kMinPerfFPS = 30;
 // The input stream will be looped as many times as needed in bitrate tests
 // to reach at least this number of frames before calculating final bitrate.
 const unsigned int kMinFramesForBitrateTests = 300;
+// The percentiles to measure for encode latency.
+const unsigned int kLoggedLatencyPercentiles[] = {50, 75, 95};
 
 // The syntax of multiple test streams is:
 //  test-stream1;test-stream2;test-stream3
@@ -190,6 +196,19 @@ static bool WriteFile(base::File* file,
   return true;
 }
 
+// Return the |percentile| from a sorted vector.
+static base::TimeDelta Percentile(
+    const std::vector<base::TimeDelta>& sorted_values,
+    unsigned int percentile) {
+  size_t size = sorted_values.size();
+  CHECK_GT(size, 0UL);
+  CHECK_LE(percentile, 100);
+  // Use Nearest Rank method in http://en.wikipedia.org/wiki/Percentile.
+  int index =
+      std::max(static_cast<int>(ceil(0.01f * percentile * size)) - 1, 0);
+  return sorted_values[index];
+}
+
 static bool IsH264(media::VideoCodecProfile profile) {
   return profile >= media::H264PROFILE_MIN && profile <= media::H264PROFILE_MAX;
 }
@@ -361,10 +380,12 @@ class VideoEncodeAcceleratorTestEnvironment : public ::testing::Environment {
   VideoEncodeAcceleratorTestEnvironment(
       scoped_ptr<base::FilePath::StringType> data,
       const base::FilePath& log_path,
-      bool run_at_fps)
-      : run_at_fps_(run_at_fps),
-        test_stream_data_(data.Pass()),
-        log_path_(log_path) {}
+      bool run_at_fps,
+      bool needs_encode_latency)
+      : test_stream_data_(data.Pass()),
+        log_path_(log_path),
+        run_at_fps_(run_at_fps),
+        needs_encode_latency_(needs_encode_latency) {}
 
   virtual void SetUp() {
     if (!log_path_.empty()) {
@@ -382,23 +403,35 @@ class VideoEncodeAcceleratorTestEnvironment : public ::testing::Environment {
     log_file_.reset();
   }
 
-  // Log one entry of machine-readable data to file.
+  // Log one entry of machine-readable data to file and LOG(INFO).
   // The log has one data entry per line in the format of "<key>: <value>".
+  // Note that Chrome OS video_VEAPerf autotest parses the output key and value
+  // pairs. Be sure to keep the autotest in sync.
   void LogToFile(const std::string& key, const std::string& value) {
+    std::string s = base::StringPrintf("%s: %s\n", key.c_str(), value.c_str());
+    LOG(INFO) << s;
     if (log_file_) {
-      std::string s =
-          base::StringPrintf("%s: %s\n", key.c_str(), value.c_str());
       log_file_->WriteAtCurrentPos(s.data(), s.length());
     }
   }
 
+  // Feed the encoder with the input buffers at the requested framerate. If
+  // false, feed as fast as possible. This is set by the command line switch
+  // "--run_at_fps".
+  bool run_at_fps() const { return run_at_fps_; }
+
+  // Whether to measure encode latency. This is set by the command line switch
+  // "--measure_latency".
+  bool needs_encode_latency() const { return needs_encode_latency_; }
+
   ScopedVector<TestStream> test_streams_;
-  bool run_at_fps_;
 
  private:
   scoped_ptr<base::FilePath::StringType> test_stream_data_;
   base::FilePath log_path_;
   scoped_ptr<base::File> log_file_;
+  bool run_at_fps_;
+  bool needs_encode_latency_;
 };
 
 enum ClientState {
@@ -559,15 +592,11 @@ class VEAClient : public VideoEncodeAccelerator::Client {
             bool force_bitrate,
             bool test_perf,
             bool mid_stream_bitrate_switch,
-            bool mid_stream_framerate_switch,
-            bool run_at_fps);
+            bool mid_stream_framerate_switch);
   ~VEAClient() override;
   void CreateEncoder();
   void DestroyEncoder();
 
-  // Return the number of encoded frames per second.
-  double frames_per_second();
-
   // VideoDecodeAccelerator::Client implementation.
   void RequireBitstreamBuffers(unsigned int input_count,
                                const gfx::Size& input_coded_size,
@@ -580,6 +609,9 @@ class VEAClient : public VideoEncodeAccelerator::Client {
  private:
   bool has_encoder() { return encoder_.get(); }
 
+  // Return the number of encoded frames per second.
+  double frames_per_second();
+
   scoped_ptr<media::VideoEncodeAccelerator> CreateFakeVEA();
   scoped_ptr<media::VideoEncodeAccelerator> CreateV4L2VEA();
   scoped_ptr<media::VideoEncodeAccelerator> CreateVaapiVEA();
@@ -603,15 +635,17 @@ class VEAClient : public VideoEncodeAccelerator::Client {
   // and accounting. Returns false once we have collected all frames we needed.
   bool HandleEncodedFrame(bool keyframe);
 
+  // Verify the minimum FPS requirement.
+  void VerifyMinFPS();
+
   // Verify that stream bitrate has been close to current_requested_bitrate_,
   // assuming current_framerate_ since the last time VerifyStreamProperties()
   // was called. Fail the test if |force_bitrate_| is true and the bitrate
   // is not within kBitrateTolerance.
   void VerifyStreamProperties();
 
-  // Test codec performance, failing the test if we are currently running
-  // the performance test.
-  void VerifyPerf();
+  // Log the performance data.
+  void LogPerf();
 
   // Write IVF file header to test_stream_->out_filename.
   void WriteIvfFileHeader();
@@ -619,9 +653,11 @@ class VEAClient : public VideoEncodeAccelerator::Client {
   // Write an IVF frame header to test_stream_->out_filename.
   void WriteIvfFrameHeader(int frame_index, size_t frame_size);
 
-  // Prepare and return a frame wrapping the data at |position| bytes in
-  // the input stream, ready to be sent to encoder.
-  scoped_refptr<media::VideoFrame> PrepareInputFrame(off_t position);
+  // Prepare and return a frame wrapping the data at |position| bytes in the
+  // input stream, ready to be sent to encoder.
+  // The input frame id is returned in |input_id|.
+  scoped_refptr<media::VideoFrame> PrepareInputFrame(off_t position,
+                                                     int32* input_id);
 
   // Update the parameters according to |mid_stream_bitrate_switch| and
   // |mid_stream_framerate_switch|.
@@ -639,11 +675,18 @@ class VEAClient : public VideoEncodeAccelerator::Client {
   // Used to notify another thread about the state. VEAClient does not own this.
   ClientStateNotification<ClientState>* note_;
 
-  // Ids assigned to VideoFrames (start at 1 for easy comparison with
-  // num_encoded_frames_).
+  // Ids assigned to VideoFrames.
   std::set<int32> inputs_at_client_;
   int32 next_input_id_;
 
+  // Encode start time of all encoded frames. The position in the vector is the
+  // frame input id.
+  std::vector<base::TimeTicks> encode_start_time_;
+  // The encode latencies of all encoded frames. We define encode latency as the
+  // time delay from input of each VideoFrame (VEA::Encode()) to output of the
+  // corresponding BitstreamBuffer (VEA::Client::BitstreamBufferReady()).
+  std::vector<base::TimeDelta> encode_latencies_;
+
   // Ids for output BitstreamBuffers.
   typedef std::map<int32, base::SharedMemory*> IdToSHM;
   ScopedVector<base::SharedMemory> output_shms_;
@@ -700,9 +743,6 @@ class VEAClient : public VideoEncodeAccelerator::Client {
 
   scoped_ptr<StreamValidator> validator_;
 
-  // The time when the encoding started.
-  base::TimeTicks encode_start_time_;
-
   // The time when the last encoded frame is ready.
   base::TimeTicks last_frame_ready_time_;
 
@@ -723,11 +763,6 @@ class VEAClient : public VideoEncodeAccelerator::Client {
 
   // The timer used to feed the encoder with the input frames.
   scoped_ptr<base::RepeatingTimer<VEAClient>> input_timer_;
-
-  // Feed the encoder with the input buffers at the |requested_framerate_|. If
-  // false, feed as fast as possible. This is set by the command line switch
-  // "--run_at_fps".
-  bool run_at_fps_;
 };
 
 VEAClient::VEAClient(TestStream* test_stream,
@@ -737,8 +772,7 @@ VEAClient::VEAClient(TestStream* test_stream,
                      bool force_bitrate,
                      bool test_perf,
                      bool mid_stream_bitrate_switch,
-                     bool mid_stream_framerate_switch,
-                     bool run_at_fps)
+                     bool mid_stream_framerate_switch)
     : state_(CS_CREATED),
       test_stream_(test_stream),
       note_(note),
@@ -763,8 +797,7 @@ VEAClient::VEAClient(TestStream* test_stream,
       requested_bitrate_(0),
       requested_framerate_(0),
       requested_subsequent_bitrate_(0),
-      requested_subsequent_framerate_(0),
-      run_at_fps_(run_at_fps) {
+      requested_subsequent_framerate_(0) {
   if (keyframe_period_)
     CHECK_LT(kMaxKeyframeDelay, keyframe_period_);
 
@@ -908,7 +941,8 @@ void VEAClient::UpdateTestStreamData(bool mid_stream_bitrate_switch,
 }
 
 double VEAClient::frames_per_second() {
-  base::TimeDelta duration = last_frame_ready_time_ - encode_start_time_;
+  CHECK(!encode_start_time_.empty());
+  base::TimeDelta duration = last_frame_ready_time_ - encode_start_time_[0];
   return num_encoded_frames_ / duration.InSecondsF();
 }
 
@@ -925,6 +959,11 @@ void VEAClient::RequireBitstreamBuffers(unsigned int input_count,
   if (g_num_frames_to_encode > 0)
     num_frames_to_encode_ = g_num_frames_to_encode;
 
+  // Speed up vector insertion.
+  encode_start_time_.reserve(num_frames_to_encode_);
+  if (g_env->needs_encode_latency())
+    encode_latencies_.reserve(num_frames_to_encode_);
+
   // We may need to loop over the stream more than once if more frames than
   // provided is required for bitrate tests.
   if (force_bitrate_ && num_frames_to_encode_ < kMinFramesForBitrateTests) {
@@ -950,8 +989,7 @@ void VEAClient::RequireBitstreamBuffers(unsigned int input_count,
     FeedEncoderWithOutput(shm);
   }
 
-  encode_start_time_ = base::TimeTicks::Now();
-  if (run_at_fps_) {
+  if (g_env->run_at_fps()) {
     input_timer_.reset(new base::RepeatingTimer<VEAClient>());
     input_timer_->Start(
         FROM_HERE, base::TimeDelta::FromSeconds(1) / current_framerate_,
@@ -1031,11 +1069,12 @@ void VEAClient::InputNoLongerNeededCallback(int32 input_id) {
   std::set<int32>::iterator it = inputs_at_client_.find(input_id);
   ASSERT_NE(it, inputs_at_client_.end());
   inputs_at_client_.erase(it);
-  if (!run_at_fps_)
+  if (!g_env->run_at_fps())
     FeedEncoderWithOneInput();
 }
 
-scoped_refptr<media::VideoFrame> VEAClient::PrepareInputFrame(off_t position) {
+scoped_refptr<media::VideoFrame> VEAClient::PrepareInputFrame(off_t position,
+                                                              int32* input_id) {
   CHECK_LE(position + test_stream_->aligned_buffer_size,
            test_stream_->mapped_aligned_in_file.length());
 
@@ -1066,8 +1105,8 @@ scoped_refptr<media::VideoFrame> VEAClient::PrepareInputFrame(off_t position) {
                          next_input_id_)));
 
   CHECK(inputs_at_client_.insert(next_input_id_).second);
-  ++next_input_id_;
 
+  *input_id = next_input_id_++;
   return frame;
 }
 
@@ -1096,16 +1135,19 @@ void VEAClient::FeedEncoderWithOneInput() {
     pos_in_input_stream_ = 0;
   }
 
+  int32 input_id;
+  scoped_refptr<media::VideoFrame> video_frame =
+      PrepareInputFrame(pos_in_input_stream_, &input_id);
+  pos_in_input_stream_ += test_stream_->aligned_buffer_size;
+
   bool force_keyframe = false;
-  if (keyframe_period_ && next_input_id_ % keyframe_period_ == 0) {
+  if (keyframe_period_ && input_id % keyframe_period_ == 0) {
     force_keyframe = true;
     ++num_keyframes_requested_;
   }
 
-  scoped_refptr<media::VideoFrame> video_frame =
-      PrepareInputFrame(pos_in_input_stream_);
-  pos_in_input_stream_ += test_stream_->aligned_buffer_size;
-
+  CHECK_EQ(input_id, static_cast<int32>(encode_start_time_.size()));
+  encode_start_time_.push_back(base::TimeTicks::Now());
   encoder_->Encode(video_frame, force_keyframe);
 }
 
@@ -1131,11 +1173,18 @@ bool VEAClient::HandleEncodedFrame(bool keyframe) {
   // return value from this method.
   CHECK_LE(num_encoded_frames_, num_frames_to_encode_);
 
+  last_frame_ready_time_ = base::TimeTicks::Now();
+
+  if (g_env->needs_encode_latency()) {
+    CHECK_LT(num_encoded_frames_, encode_start_time_.size());
+    base::TimeTicks start_time = encode_start_time_[num_encoded_frames_];
+    CHECK(!start_time.is_null());
+    encode_latencies_.push_back(last_frame_ready_time_ - start_time);
+  }
+
   ++num_encoded_frames_;
   ++num_frames_since_last_check_;
 
-  last_frame_ready_time_ = base::TimeTicks::Now();
-
   // Because the keyframe behavior requirements are loose, we give
   // the encoder more freedom here. It could either deliver a keyframe
   // immediately after we requested it, which could be for a frame number
@@ -1164,13 +1213,14 @@ bool VEAClient::HandleEncodedFrame(bool keyframe) {
         requested_subsequent_framerate_ != current_framerate_) {
       SetStreamParameters(requested_subsequent_bitrate_,
                           requested_subsequent_framerate_);
-      if (run_at_fps_ && input_timer_)
+      if (g_env->run_at_fps() && input_timer_)
         input_timer_->Start(
             FROM_HERE, base::TimeDelta::FromSeconds(1) / current_framerate_,
             base::Bind(&VEAClient::OnInputTimer, base::Unretained(this)));
     }
   } else if (num_encoded_frames_ == num_frames_to_encode_) {
-    VerifyPerf();
+    LogPerf();
+    VerifyMinFPS();
     VerifyStreamProperties();
     SetState(CS_FINISHED);
     return false;
@@ -1179,13 +1229,26 @@ bool VEAClient::HandleEncodedFrame(bool keyframe) {
   return true;
 }
 
-void VEAClient::VerifyPerf() {
-  double measured_fps = frames_per_second();
-  LOG(INFO) << "Measured encoder FPS: " << measured_fps;
+void VEAClient::LogPerf() {
   g_env->LogToFile("Measured encoder FPS",
-                   base::StringPrintf("%.3f", measured_fps));
+                   base::StringPrintf("%.3f", frames_per_second()));
+
+  // Log encode latencies.
+  if (g_env->needs_encode_latency()) {
+    std::sort(encode_latencies_.begin(), encode_latencies_.end());
+    for (const auto& percentile : kLoggedLatencyPercentiles) {
+      base::TimeDelta latency = Percentile(encode_latencies_, percentile);
+      g_env->LogToFile(
+          base::StringPrintf("Encode latency for the %dth percentile",
+                             percentile),
+          base::StringPrintf("%" PRId64 " us", latency.InMicroseconds()));
+    }
+  }
+}
+
+void VEAClient::VerifyMinFPS() {
   if (test_perf_)
-    EXPECT_GE(measured_fps, kMinPerfFPS);
+    EXPECT_GE(frames_per_second(), kMinPerfFPS);
 }
 
 void VEAClient::VerifyStreamProperties() {
@@ -1292,11 +1355,10 @@ TEST_P(VideoEncodeAcceleratorTest, TestSimpleEncode) {
          !g_env->test_streams_[test_stream_index]->out_filename.empty());
 
     notes.push_back(new ClientStateNotification<ClientState>());
-    clients.push_back(
-        new VEAClient(g_env->test_streams_[test_stream_index], notes.back(),
-                      encoder_save_to_file, keyframe_period, force_bitrate,
-                      test_perf, mid_stream_bitrate_switch,
-                      mid_stream_framerate_switch, g_env->run_at_fps_));
+    clients.push_back(new VEAClient(
+        g_env->test_streams_[test_stream_index], notes.back(),
+        encoder_save_to_file, keyframe_period, force_bitrate, test_perf,
+        mid_stream_bitrate_switch, mid_stream_framerate_switch));
 
     encoder_thread.message_loop()->PostTask(
         FROM_HERE,
@@ -1396,6 +1458,7 @@ int main(int argc, char** argv) {
   DCHECK(cmd_line);
 
   bool run_at_fps = false;
+  bool needs_encode_latency = false;
   base::FilePath log_path;
 
   base::CommandLine::SwitchMap switches = cmd_line->GetSwitches();
@@ -1417,6 +1480,10 @@ int main(int argc, char** argv) {
       CHECK(base::StringToInt(input, &content::g_num_frames_to_encode));
       continue;
     }
+    if (it->first == "measure_latency") {
+      needs_encode_latency = true;
+      continue;
+    }
     if (it->first == "fake_encoder") {
       content::g_fake_encoder = true;
       continue;
@@ -1432,6 +1499,13 @@ int main(int argc, char** argv) {
     LOG(FATAL) << "Unexpected switch: " << it->first << ":" << it->second;
   }
 
+  if (needs_encode_latency && !run_at_fps) {
+    // Encode latency can only be measured with --run_at_fps. Otherwise, we get
+    // skewed results since it may queue too many frames at once with the same
+    // encode start time.
+    LOG(FATAL) << "--measure_latency requires --run_at_fps enabled to work.";
+  }
+
 #if defined(OS_CHROMEOS) && defined(ARCH_CPU_X86_FAMILY)
   content::VaapiWrapper::PreSandboxInitialization();
 #endif
@@ -1440,7 +1514,8 @@ int main(int argc, char** argv) {
       reinterpret_cast<content::VideoEncodeAcceleratorTestEnvironment*>(
           testing::AddGlobalTestEnvironment(
               new content::VideoEncodeAcceleratorTestEnvironment(
-                  test_stream_data.Pass(), log_path, run_at_fps)));
+                  test_stream_data.Pass(), log_path, run_at_fps,
+                  needs_encode_latency)));
 
   return RUN_ALL_TESTS();
 }