vea_unittest: Calculate per-frame encode latency

content/common/gpu/media/video_encode_accelerator_unittest.cc

Index: content/common/gpu/media/video_encode_accelerator_unittest.cc
diff --git a/content/common/gpu/media/video_encode_accelerator_unittest.cc b/content/common/gpu/media/video_encode_accelerator_unittest.cc
index 19a9d34c25c0cbb16f2de12380f91acce7b3eaa7..fd44eb34f06c8c60e329a861bf23dfc44e330c0f 100644
--- a/content/common/gpu/media/video_encode_accelerator_unittest.cc
+++ b/content/common/gpu/media/video_encode_accelerator_unittest.cc
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <algorithm>
+
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/command_line.h"
@@ -69,6 +71,8 @@ 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.
+static unsigned int kLoggedLatencyPercentiles[] = {50, 75, 95};
 
 // The syntax of multiple test streams is:
 //  test-stream1;test-stream2;test-stream3
@@ -189,6 +193,19 @@ 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, 0);
+  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;
 }
@@ -381,12 +398,14 @@ 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());
     }
   }
@@ -564,9 +583,6 @@ class VEAClient : public VideoEncodeAccelerator::Client {
   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,
@@ -579,6 +595,14 @@ class VEAClient : public VideoEncodeAccelerator::Client {
  private:
   bool has_encoder() { return encoder_.get(); }
 
+  // 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.
+  bool needs_encode_latency() { return run_at_fps_; }
+
+  // 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();
@@ -602,15 +626,17 @@ 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();
@@ -618,9 +644,11 @@ 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|.
@@ -638,11 +666,18 @@ 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_;
@@ -699,9 +734,6 @@ 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_;
 
@@ -907,7 +939,7 @@ void VEAClient::UpdateTestStreamData(bool mid_stream_bitrate_switch,
 }
 
 double VEAClient::frames_per_second() {
-  base::TimeDelta duration = last_frame_ready_time_ - encode_start_time_;
+  base::TimeDelta duration = last_frame_ready_time_ - encode_start_time_[0];
   return num_encoded_frames_ / duration.InSecondsF();
 }
 
@@ -924,6 +956,11 @@ 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 (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) {
@@ -949,7 +986,6 @@ void VEAClient::RequireBitstreamBuffers(unsigned int input_count,
     FeedEncoderWithOutput(shm);
   }
 
-  encode_start_time_ = base::TimeTicks::Now();
   if (run_at_fps_) {
     input_timer_.reset(new base::RepeatingTimer<VEAClient>());
     input_timer_->Start(
@@ -1034,7 +1070,8 @@ void VEAClient::InputNoLongerNeededCallback(int32 input_id) {
     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());
 
@@ -1065,8 +1102,8 @@ 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;
 }
 
@@ -1095,16 +1132,19 @@ 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);
 }
 
@@ -1130,11 +1170,17 @@ 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 (needs_encode_latency()) {
+    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
@@ -1169,7 +1215,8 @@ bool VEAClient::HandleEncodedFrame(bool keyframe) {
             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;
@@ -1178,13 +1225,27 @@ 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() {
+  // Log measured FPS.
   g_env->LogToFile("Measured encoder FPS",
-                   base::StringPrintf("%.3f", measured_fps));
+                   base::StringPrintf("%.3f", frames_per_second()));
+
+  // Log encode latencies.
+  if (needs_encode_latency()) {
+    std::sort(encode_latencies_.begin(), encode_latencies_.end());
+    for (unsigned int percentile : kLoggedLatencyPercentiles) {

[Pawel Osciak, 2015/05/13 03:21:18]

s/unsigned int/const auto&/ ?

[Justin Chuang, 2015/05/13 13:59:35]

Done. I changed to unsigned int because Percentile() uses this type explicitly,
but using auto is also okay.

+      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() {