add unit test for datarate control

Adds some basic datarate control tests..

Change-Id: I6eff18aa58ef7cfd14886c6b1e048247cd1ad247

test/datarate_test.cc

+/*
+ *  Copyright (c) 2012 The WebM 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 "test/encode_test_driver.h"
+#include "test/i420_video_source.h"
+#include "third_party/googletest/src/include/gtest/gtest.h"
+namespace {
+
+class DatarateTest : public ::libvpx_test::EncoderTest,
+    public ::testing::TestWithParam<enum libvpx_test::TestMode> {
+ protected:
+  virtual void SetUp() {
+    InitializeConfig();
+    SetMode(GetParam());
+    ResetModel();
+  }
+
+  virtual void ResetModel() {
+    last_pts_ = 0;
+    bits_in_buffer_model_ = cfg_.rc_target_bitrate * cfg_.rc_buf_initial_sz;
+    frame_number_ = 0;
+    first_drop_ = 0;
+    bits_total_ = 0;
+    duration_ = 0.0;
+  }
+
+  virtual bool Continue() const {
+    return !HasFatalFailure() && !abort_;
+  }
+
+  virtual void PreEncodeFrameHook(::libvpx_test::VideoSource *video,
+                                  ::libvpx_test::Encoder *encoder) {
+    const vpx_rational_t tb = video->timebase();
+    timebase_ = static_cast<double>(tb.num) / tb.den;
+    duration_ = 0;
+  }
+
+  virtual void FramePktHook(const vpx_codec_cx_pkt_t *pkt) {
+    // Time since last timestamp = duration.
+    vpx_codec_pts_t duration = pkt->data.frame.pts - last_pts_;
+
+    // TODO(jimbankoski): Remove these lines when the issue:
+    // http://code.google.com/p/webm/issues/detail?id=496 is fixed.
+    // For now the codec assumes buffer starts at starting buffer rate
+    // plus one frame's time.
+    if (last_pts_ == 0)
+      duration = 1;
+
+    // Add to the buffer the bits we'd expect from a constant bitrate server.
+    bits_in_buffer_model_ += duration * timebase_ * cfg_.rc_target_bitrate
+        * 1000;
+
+    /* Test the buffer model here before subtracting the frame. Do so because
+     * the way the leaky bucket model works in libvpx is to allow the buffer to
+     * empty - and then stop showing frames until we've got enough bits to
+     * show one. */
+    ASSERT_GE(bits_in_buffer_model_, 0) << "Buffer Underrun at frame "
+        << pkt->data.frame.pts;
+
+    const int frame_size_in_bits = pkt->data.frame.sz * 8;
+
+    // Subtract from the buffer the bits associated with a played back frame.
+    bits_in_buffer_model_ -= frame_size_in_bits;
+
+    // Update the running total of bits for end of test datarate checks.
+    bits_total_ += frame_size_in_bits ;
+
+    // If first drop not set and we have a drop set it to this time.
+    if (!first_drop_ && duration > 1)
+      first_drop_ = last_pts_ + 1;
+
+    // Update the most recent pts.
+    last_pts_ = pkt->data.frame.pts;
+
+    // We update this so that we can calculate the datarate minus the last
+    // frame encoded in the file.
+    bits_in_last_frame_ = frame_size_in_bits;
+
+    ++frame_number_;
+  }
+
+  virtual void EndPassHook(void) {
+    if (bits_total_) {
+      const double file_size_in_kb = bits_total_ / 1000;  /* bits per kilobit */
+
+      duration_ = (last_pts_ + 1) * timebase_;
+
+      // Effective file datarate includes the time spent prebuffering.
+      effective_datarate_ = (bits_total_ - bits_in_last_frame_) / 1000.0
+          / (cfg_.rc_buf_initial_sz / 1000.0 + duration_);
+
+      file_datarate_ = file_size_in_kb / duration_;
+    }
+  }
+
+  vpx_codec_pts_t last_pts_;
+  int bits_in_buffer_model_;
+  double timebase_;
+  int frame_number_;
+  vpx_codec_pts_t first_drop_;
+  int64_t bits_total_;
+  double duration_;
+  double file_datarate_;
+  double effective_datarate_;
+  int bits_in_last_frame_;
+};
+
+TEST_P(DatarateTest, BasicBufferModel) {
+  cfg_.rc_buf_initial_sz = 500;
+  cfg_.rc_dropframe_thresh = 1;
+  cfg_.rc_max_quantizer = 56;
+  cfg_.rc_end_usage = VPX_CBR;
+  // 2 pass cbr datarate control has a bug hidden by the small # of
+  // frames selected in this encode. The problem is that even if the buffer is
+  // negative we produce a keyframe on a cutscene. Ignoring datarate
+  // constraints
+  // TODO(jimbankoski): ( Fix when issue
+  // http://code.google.com/p/webm/issues/detail?id=495 is addressed. )
+  ::libvpx_test::I420VideoSource video("hantro_collage_w352h288.yuv", 352, 288,
+                                       30, 1, 0, 140);
+
+  for (int i = 70; i < 700; i += 200) {
+    cfg_.rc_target_bitrate = i;
+    ResetModel();
+    ASSERT_NO_FATAL_FAILURE(RunLoop(&video));
+    ASSERT_GE(cfg_.rc_target_bitrate, effective_datarate_)
+        << " The datarate for the file exceeds the target!";
+
+    ASSERT_LE(cfg_.rc_target_bitrate, file_datarate_ * 1.3)
+        << " The datarate for the file missed the target!";
+  }
+}
+
+TEST_P(DatarateTest, ChangingDropFrameThresh) {
+  cfg_.rc_buf_initial_sz = 500;
+  cfg_.rc_max_quantizer = 36;
+  cfg_.rc_end_usage = VPX_CBR;
+  cfg_.rc_target_bitrate = 200;
+  cfg_.kf_mode = VPX_KF_DISABLED;
+
+  const int frame_count = 40;
+  ::libvpx_test::I420VideoSource video("hantro_collage_w352h288.yuv", 352, 288,
+                                       30, 1, 0, frame_count);
+
+  // Here we check that the first dropped frame gets earlier and earlier
+  // as the drop frame threshold is increased.
+
+  const int kDropFrameThreshTestStep = 30;
+  vpx_codec_pts_t last_drop = frame_count;
+  for (int i = 1; i < 91; i += kDropFrameThreshTestStep) {
+    cfg_.rc_dropframe_thresh = i;
+    ResetModel();
+    ASSERT_NO_FATAL_FAILURE(RunLoop(&video));
+    ASSERT_LE(first_drop_, last_drop)
+        << " The first dropped frame for drop_thresh " << i
+        << " > first dropped frame for drop_thresh "
+        << i - kDropFrameThreshTestStep;
+    last_drop = first_drop_;
+  }
+}
+
+INSTANTIATE_TEST_CASE_P(AllModes, DatarateTest, ALL_TEST_MODES);
+}  // namespace

test/test.mk

@@ -12,6 +12,7 @@ LIBVPX_TEST_SRCS-yes += video_source.h
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += altref_test.cc
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += config_test.cc
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += cq_test.cc
+LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += datarate_test.cc
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += encode_test_driver.cc
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += encode_test_driver.h
 LIBVPX_TEST_SRCS-$(CONFIG_VP8_ENCODER) += error_resilience_test.cc