test/vp8_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 "vp8_rtcd.h"
}

#include "test/acm_random.h"
#include "third_party/googletest/src/include/gtest/gtest.h"
#include "vpx/vpx_integer.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;
  }
}

using libvpx_test::ACMRandom;

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