webrtc/tools/frame_analyzer/video_quality_analysis.cc

/*
 *  Copyright (c) 2012 The WebRTC 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 "webrtc/tools/frame_analyzer/video_quality_analysis.h"

#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <string>

#define STATS_LINE_LENGTH 32

namespace webrtc {
namespace test {

using std::string;

int GetI420FrameSize(int width, int height) {
  int half_width = (width + 1) >> 1;
  int half_height = (height + 1) >> 1;

  int y_plane = width * height;  // I420 Y plane.
  int u_plane = half_width * half_height;  // I420 U plane.
  int v_plane = half_width * half_height;  // I420 V plane.

  return y_plane + u_plane + v_plane;
}

int ExtractFrameSequenceNumber(std::string line) {
  size_t space_position = line.find(' ');
  if (space_position == string::npos) {
    return -1;
  }
  std::string frame = line.substr(0, space_position);

  size_t underscore_position = frame.find('_');
  if (underscore_position == string::npos) {
    return -1;
  }
  std::string frame_number = frame.substr(underscore_position + 1);

  return strtol(frame_number.c_str(), NULL, 10);
}

int ExtractDecodedFrameNumber(std::string line) {
  size_t space_position = line.find(' ');
  if (space_position == string::npos) {
    return -1;
  }
  std::string decoded_number = line.substr(space_position + 1);

  return strtol(decoded_number.c_str(), NULL, 10);
}

bool IsThereBarcodeError(std::string line) {
  size_t barcode_error_position = line.find("Barcode error");
  if (barcode_error_position != string::npos) {
    return true;
  }
  return false;
}

bool GetNextStatsLine(FILE* stats_file, char* line) {
  int chars = 0;
  char buf = 0;

  while (buf != '\n') {
    size_t chars_read = fread(&buf, 1, 1, stats_file);
    if (chars_read != 1 || feof(stats_file)) {
      return false;
    }
    line[chars] = buf;
    ++chars;
  }
  line[chars-1] = '\0';  // Strip the trailing \n and put end of string.
  return true;
}

bool GetNextI420Frame(FILE* input_file, int width, int height,
                      uint8* result_frame) {
  int frame_size = GetI420FrameSize(width, height);
  bool errors = false;

  size_t bytes_read = fread(result_frame, 1, frame_size, input_file);
  if (bytes_read != static_cast<size_t>(frame_size)) {
    // If end-of-file is reached, don't print an error.
    if (feof(input_file)) {
      return false;
    }
    fprintf(stdout, "Error while reading frame from file\n");
    errors = true;
  }
  return !errors;
}

bool ExtractFrameFromI420(const char* i420_file_name, int width, int height,
                          int frame_number, uint8* result_frame) {
  int frame_size = GetI420FrameSize(width, height);
  int offset = frame_number * frame_size;  // Calculate offset for the frame.
  bool errors = false;

  FILE* input_file = fopen(i420_file_name, "rb");
  if (input_file == NULL) {
    fprintf(stderr, "Couldn't open input file for reading: %s\n",
            i420_file_name);
    return false;
  }

  // Change stream pointer to new offset.
  fseek(input_file, offset, SEEK_SET);

  size_t bytes_read = fread(result_frame, 1, frame_size, input_file);
  if (bytes_read != static_cast<size_t>(frame_size) &&
      ferror(input_file)) {
    fprintf(stdout, "Error while reading frame no %d from file %s\n",
            frame_number, i420_file_name);
    errors = true;
  }
  fclose(input_file);
  return !errors;
}

double CalculateMetrics(VideoAnalysisMetricsType video_metrics_type,
                        const uint8* ref_frame,  const uint8* test_frame,
                        int width, int height) {
  if (!ref_frame || !test_frame)
    return -1;
  else if (height < 0 || width < 0)
    return -1;
  int half_width = (width + 1) >> 1;
  int half_height = (height + 1) >> 1;
  const uint8* src_y_a = ref_frame;
  const uint8* src_u_a = src_y_a + width * height;
  const uint8* src_v_a = src_u_a + half_width * half_height;
  const uint8* src_y_b = test_frame;
  const uint8* src_u_b = src_y_b + width * height;
  const uint8* src_v_b = src_u_b + half_width * half_height;

  int stride_y = width;
  int stride_uv = half_width;

  double result = 0.0;

  switch (video_metrics_type) {
    case kPSNR:
      // In the following: stride is determined by width.
      result = libyuv::I420Psnr(src_y_a, width, src_u_a, half_width,
                                src_v_a, half_width, src_y_b, width,
                                src_u_b, half_width, src_v_b, half_width,
                                width, height);
      // LibYuv sets the max psnr value to 128, we restrict it to 48.
      // In case of 0 mse in one frame, 128 can skew the results significantly.
      result = (result > 48.0) ? 48.0 : result;
      break;
    case kSSIM:
      result = libyuv::I420Ssim(src_y_a, stride_y, src_u_a, stride_uv,
                                src_v_a, stride_uv, src_y_b, stride_y,
                                src_u_b, stride_uv, src_v_b, stride_uv,
                                width, height);
      break;
    default:
      assert(false);
  }

  return result;
}

void RunAnalysis(const char* reference_file_name, const char* test_file_name,
                 const char* stats_file_name, int width, int height,
                 ResultsContainer* results) {
  int size = GetI420FrameSize(width, height);
  FILE* stats_file = fopen(stats_file_name, "r");

  // String buffer for the lines in the stats file.
  char line[STATS_LINE_LENGTH];

  // Allocate buffers for test and reference frames.
  uint8* test_frame = new uint8[size];
  uint8* reference_frame = new uint8[size];
  int previous_frame_number = -1;

  // While there are entries in the stats file.
  while (GetNextStatsLine(stats_file, line)) {
    int extracted_test_frame = ExtractFrameSequenceNumber(line);
    int decoded_frame_number = ExtractDecodedFrameNumber(line);

    // If there was problem decoding the barcode in this frame or the frame has
    // been duplicated, continue.
    if (IsThereBarcodeError(line) ||
        decoded_frame_number == previous_frame_number) {
      continue;
    }

    assert(extracted_test_frame != -1);
    assert(decoded_frame_number != -1);

    ExtractFrameFromI420(test_file_name, width, height, extracted_test_frame,
                         test_frame);
    ExtractFrameFromI420(reference_file_name, width, height,
                         decoded_frame_number, reference_frame);

    // Calculate the PSNR and SSIM.
    double result_psnr = CalculateMetrics(kPSNR, reference_frame, test_frame,
                                          width, height);
    double result_ssim = CalculateMetrics(kSSIM, reference_frame, test_frame,
                                          width, height);

    previous_frame_number = decoded_frame_number;

    // Fill in the result struct.
    AnalysisResult result;
    result.frame_number = decoded_frame_number;
    result.psnr_value = result_psnr;
    result.ssim_value = result_ssim;

    results->frames.push_back(result);
  }

  // Cleanup.
  fclose(stats_file);
  delete[] test_frame;
  delete[] reference_frame;
}

void PrintMaxRepeatedAndSkippedFrames(const char* stats_file_name) {
  FILE* stats_file = fopen(stats_file_name, "r");
  char line[STATS_LINE_LENGTH];

  int repeated_frames = 1;
  int max_repeated_frames = 1;
  int max_skipped_frames = 1;
  int previous_frame_number = -1;

  while (GetNextStatsLine(stats_file, line)) {
    int decoded_frame_number = ExtractDecodedFrameNumber(line);

    if (decoded_frame_number == -1) {
      continue;
    }

    // Calculate how many frames a cluster of repeated frames contains.
    if (decoded_frame_number == previous_frame_number) {
      ++repeated_frames;
      if (repeated_frames > max_repeated_frames) {
        max_repeated_frames = repeated_frames;
      }
    } else {
      repeated_frames = 1;
    }

    // Calculate how much frames have been skipped.
    if (decoded_frame_number != 0 && previous_frame_number != -1) {
      int skipped_frames = decoded_frame_number - previous_frame_number - 1;
      if (skipped_frames > max_skipped_frames) {
        max_skipped_frames = skipped_frames;
      }
    }
    previous_frame_number = decoded_frame_number;
  }
  fprintf(stdout, "Max_repeated:%d Max_skipped:%d\n", max_repeated_frames,
          max_skipped_frames);
}

void PrintAnalysisResults(ResultsContainer* results) {
  std::vector<AnalysisResult>::iterator iter;
  int frames_counter = 0;

  fprintf(stdout, "BSTATS\n");
  for (iter = results->frames.begin(); iter != results->frames.end(); ++iter) {
    ++frames_counter;
    fprintf(stdout, "%f %f;", iter->psnr_value, iter->ssim_value);
  }
  fprintf(stdout, "ESTATS\n");
  if (frames_counter > 0) {
    fprintf(stdout, "Unique_frames_count:%d\n", frames_counter);
  } else {
    fprintf(stdout, "Unique_frames_count:undef\n");
  }
}

}  // namespace test
}  // namespace webrtc