test/idct8x8_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 <stdlib.h>
#include <string.h>

#include "third_party/googletest/src/include/gtest/gtest.h"

#include "./vpx_dsp_rtcd.h"
#include "test/acm_random.h"
#include "vpx/vpx_integer.h"

using libvpx_test::ACMRandom;

namespace {

#ifdef _MSC_VER
static int round(double x) {
  if (x < 0)
    return static_cast<int>(ceil(x - 0.5));
  else
    return static_cast<int>(floor(x + 0.5));
}
#endif

void reference_dct_1d(double input[8], double output[8]) {
  const double kPi = 3.141592653589793238462643383279502884;
  const double kInvSqrt2 = 0.707106781186547524400844362104;
  for (int k = 0; k < 8; k++) {
    output[k] = 0.0;
    for (int n = 0; n < 8; n++)
      output[k] += input[n]*cos(kPi*(2*n+1)*k/16.0);
    if (k == 0)
      output[k] = output[k]*kInvSqrt2;
  }
}

void reference_dct_2d(int16_t input[64], double output[64]) {
  // First transform columns
  for (int i = 0; i < 8; ++i) {
    double temp_in[8], temp_out[8];
    for (int j = 0; j < 8; ++j)
      temp_in[j] = input[j*8 + i];
    reference_dct_1d(temp_in, temp_out);
    for (int j = 0; j < 8; ++j)
      output[j*8 + i] = temp_out[j];
  }
  // Then transform rows
  for (int i = 0; i < 8; ++i) {
    double temp_in[8], temp_out[8];
    for (int j = 0; j < 8; ++j)
      temp_in[j] = output[j + i*8];
    reference_dct_1d(temp_in, temp_out);
    for (int j = 0; j < 8; ++j)
      output[j + i*8] = temp_out[j];
  }
  // Scale by some magic number
  for (int i = 0; i < 64; ++i)
    output[i] *= 2;
}

TEST(VP9Idct8x8Test, AccuracyCheck) {
  ACMRandom rnd(ACMRandom::DeterministicSeed());
  const int count_test_block = 10000;
  for (int i = 0; i < count_test_block; ++i) {
    int16_t input[64];
    tran_low_t coeff[64];
    double output_r[64];
    uint8_t dst[64], src[64];

    for (int j = 0; j < 64; ++j) {
      src[j] = rnd.Rand8();
      dst[j] = rnd.Rand8();
    }
    // Initialize a test block with input range [-255, 255].
    for (int j = 0; j < 64; ++j)
      input[j] = src[j] - dst[j];

    reference_dct_2d(input, output_r);
    for (int j = 0; j < 64; ++j)
      coeff[j] = round(output_r[j]);
    vpx_idct8x8_64_add_c(coeff, dst, 8);
    for (int j = 0; j < 64; ++j) {
      const int diff = dst[j] - src[j];
      const int error = diff * diff;
      EXPECT_GE(1, error)
          << "Error: 8x8 FDCT/IDCT has error " << error
          << " at index " << j;
    }
  }
}

}  // namespace