Added unit test for 4x4 forward dct

Change-Id: I1607676879c29adc0173a3c0355a0e5d8a84fc3b

test/fdct4x4_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 <math.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+
+extern "C" {
+#include "vpx_rtcd.h"
+}
+
+#include "third_party/googletest/src/include/gtest/gtest.h"
+#include "vpx/vpx_integer.h"
+#include "vpx_mem/vpx_mem.h"
+#include "vp8/encoder/onyx_int.h"
+
+
+namespace {
+
+const int cospi8sqrt2minus1 = 20091;
+const int sinpi8sqrt2 = 35468;
+
+void reference_idct4x4(const int16_t *input, int16_t *output) {
+  const int16_t *ip = input;
+  int16_t *op = output;
+
+  for (int i = 0; i < 4; ++i) {
+    const int a1 = ip[0] + ip[8];
+    const int b1 = ip[0] - ip[8];
+    const int temp1 = (ip[4] * sinpi8sqrt2) >> 16;
+    const int temp2 = ip[12] + ((ip[12] * cospi8sqrt2minus1) >> 16);
+    const int c1 = temp1 - temp2;
+    const int temp3 = ip[4] + ((ip[4] * cospi8sqrt2minus1) >> 16);
+    const int temp4 = (ip[12] * sinpi8sqrt2) >> 16;
+    const int d1 = temp3 + temp4;
+    op[0] = a1 + d1;
+    op[12] = a1 - d1;
+    op[4] = b1 + c1;
+    op[8] = b1 - c1;
+    ++ip;
+    ++op;
+  }
+  ip = output;
+  op = output;
+  for (int i = 0; i < 4; ++i) {
+    const int a1 = ip[0] + ip[2];
+    const int b1 = ip[0] - ip[2];
+    const int temp1 = (ip[1] * sinpi8sqrt2) >> 16;
+    const int temp2 = ip[3] + ((ip[3] * cospi8sqrt2minus1) >> 16);
+    const int c1 = temp1 - temp2;
+    const int temp3 = ip[1] + ((ip[1] * cospi8sqrt2minus1) >> 16);
+    const int temp4 = (ip[3] * sinpi8sqrt2) >> 16;
+    const int d1 = temp3 + temp4;
+    op[0] = (a1 + d1 + 4) >> 3;
+    op[3] = (a1 - d1 + 4) >> 3;
+    op[1] = (b1 + c1 + 4) >> 3;
+    op[2] = (b1 - c1 + 4) >> 3;
+    ip += 4;
+    op += 4;
+  }
+}
+
+// This is a class that generate random numbers for test input.
+class ACMRandom {
+public:
+  explicit ACMRandom(int seed) { Reset(seed); }
+
+  void Reset(int seed) { srand(seed); }
+
+  uint8_t Rand8(void) { return (rand() >> 8) & 0xff; }
+
+  int PseudoUniform(int range) { return (rand() >> 8) % range; }
+
+  int operator()(int n) { return PseudoUniform(n); }
+
+  static int DeterministicSeed(void) { return 0xbaba; }
+};
+
+
+TEST(Vp8FdctTest, SignBiasCheck) {
+  ACMRandom rnd(ACMRandom::DeterministicSeed());
+  int16_t test_input_block[16];
+  int16_t test_output_block[16];
+  const int pitch = 8;
+  int count_sign_block[16][2];
+  const int count_test_block = 1000000;
+
+  memset(count_sign_block, 0, sizeof(count_sign_block));
+
+  for (int i = 0; i < count_test_block; ++i) {
+    // Initialize a test block with input range [-255, 255].
+    for (int j = 0; j < 16; ++j)
+      test_input_block[j] = rnd.Rand8() - rnd.Rand8();
+
+    vp8_short_fdct4x4_c(test_input_block, test_output_block, pitch);
+
+    for (int j = 0; j < 16; ++j) {
+      if (test_output_block[j] < 0)
+        ++count_sign_block[j][0];
+      else if (test_output_block[j] > 0)
+        ++count_sign_block[j][1];
+    }
+  }
+
+  bool bias_acceptable = true;
+  for (int j = 0; j < 16; ++j)
+    bias_acceptable = bias_acceptable &&
+    (abs(count_sign_block[j][0] - count_sign_block[j][1]) < 10000);
+
+  EXPECT_EQ(true, bias_acceptable)
+    << "Error: 4x4 FDCT has a sign bias > 1% for input range [-255, 255]";
+
+  memset(count_sign_block, 0, sizeof(count_sign_block));
+
+  for (int i = 0; i < count_test_block; ++i) {
+    // Initialize a test block with input range [-15, 15].
+    for (int j = 0; j < 16; ++j)
+      test_input_block[j] = (rnd.Rand8() >> 4) - (rnd.Rand8() >> 4);
+
+    vp8_short_fdct4x4_c(test_input_block, test_output_block, pitch);
+
+    for (int j = 0; j < 16; ++j) {
+      if (test_output_block[j] < 0)
+        ++count_sign_block[j][0];
+      else if (test_output_block[j] > 0)
+        ++count_sign_block[j][1];
+    }
+  }
+
+  bias_acceptable = true;
+  for (int j = 0; j < 16; ++j)
+    bias_acceptable = bias_acceptable &&
+    (abs(count_sign_block[j][0] - count_sign_block[j][1]) < 100000);
+
+  EXPECT_EQ(true, bias_acceptable)
+    << "Error: 4x4 FDCT has a sign bias > 10% for input range [-15, 15]";
+};
+
+TEST(Vp8FdctTest, RoundTripErrorCheck) {
+  ACMRandom rnd(ACMRandom::DeterministicSeed());
+  int max_error = 0;
+  double total_error = 0;
+  const int count_test_block = 1000000;
+  for (int i = 0; i < count_test_block; ++i) {
+    int16_t test_input_block[16];
+    int16_t test_temp_block[16];
+    int16_t test_output_block[16];
+
+    // Initialize a test block with input range [-255, 255].
+    for (int j = 0; j < 16; ++j)
+      test_input_block[j] = rnd.Rand8() - rnd.Rand8();
+
+    const int pitch = 8;
+    vp8_short_fdct4x4_c(test_input_block, test_temp_block, pitch);
+    reference_idct4x4(test_temp_block, test_output_block);
+
+    for (int j = 0; j < 16; ++j) {
+      const int diff = test_input_block[j] - test_output_block[j];
+      const int error = diff * diff;
+      if (max_error < error)
+        max_error = error;
+      total_error += error;
+    }
+  }
+
+  EXPECT_GE(1, max_error )
+    << "Error: FDCT/IDCT has an individual roundtrip error > 1";
+
+  EXPECT_GE(count_test_block, total_error)
+    << "Error: FDCT/IDCT has average roundtrip error > 1 per block";
+};
+
+}  // namespace

test/test.mk

@@ -6,6 +6,7 @@ LIBVPX_TEST_SRCS-yes += encode_test_driver.h
 LIBVPX_TEST_SRCS-yes += i420_video_source.h
 LIBVPX_TEST_SRCS-yes += idctllm_test.cc
 LIBVPX_TEST_SRCS-yes += intrapred_test.cc
+LIBVPX_TEST_SRCS-yes += fdct4x4_test.cc
 LIBVPX_TEST_SRCS-yes += keyframe_test.cc
 LIBVPX_TEST_SRCS-yes += pp_filter_test.cc
 LIBVPX_TEST_SRCS-yes += resize_test.cc