cpp_thumbnail_generator/src/ThumbnailGenerator.cpp

#include "include/ThumbnailGenerator.hpp"
#include <iostream>
#include <libavutil/pixdesc.h>
#include <libavutil/pixfmt.h>
extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/avutil.h>
#include <libavutil/error.h>
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>
}

ThumbnailGenerator::ThumbnailGenerator() { av_register_all(); }

int ThumbnailGenerator::get_duration_microseconds(std::string input_file_path) {
  // Open input file and allocate format context
  AVFormatContext *format_ctx = nullptr;
  int ret = avformat_open_input(&format_ctx, input_file_path.c_str(), nullptr,
                                nullptr);
  if (ret < 0) {
    std::cerr << "Could not open input file: " << input_file_path << std::endl;
    // char buff[256];
    // av_strerror(ret, buff, 256);
    // printf(buff);

    std::cerr << "Error: " << ret << std::endl;
    AVERROR(ret);

    throw std::runtime_error("Could not open input file");
  }

  int duration = format_ctx->duration;

  avformat_close_input(&format_ctx);

  return duration;
}

std::string ThumbnailGenerator::generate_thumbnail(std::string input_file_path) {
  std::cout << "generating thumbnail: " << input_file_path << std::endl;

  // Open input file and allocate format context
  AVFormatContext *format_ctx = nullptr;
  int ret = avformat_open_input(&format_ctx, input_file_path.c_str(), nullptr,
                                nullptr);
  if (ret < 0) {
    std::cerr << "Could not open input file: " << input_file_path << std::endl;
    // char buff[256];
    // av_strerror(ret, buff, 256);
    // printf(buff);

    std::cerr << "Error: " << ret << std::endl;
    AVERROR(ret);

    throw std::runtime_error("Could not open input file");
  }

  // Retrieve stream information
  if (avformat_find_stream_info(format_ctx, nullptr) < 0) {
    std::cerr << "Could not find stream information" << std::endl;
    throw std::runtime_error("Could not find stream information");
  }

  // Find video stream
  int video_stream_idx = -1;
  for (unsigned int i = 0; i < format_ctx->nb_streams; ++i) {
    if (format_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
      video_stream_idx = i;
      break;
    }
  }

  if (video_stream_idx == -1) {
    std::cerr << "Could not find video stream" << std::endl;
    throw std::runtime_error("Could not find video stream");
  }

  // Get codec parameters and codec context
  AVCodecParameters *codecpar = format_ctx->streams[video_stream_idx]->codecpar;
  AVCodec *codec = avcodec_find_decoder(codecpar->codec_id);
  AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
  avcodec_parameters_to_context(codec_ctx, codecpar);

  // Open codec
  if (avcodec_open2(codec_ctx, codec, nullptr) < 0) {
    std::cerr << "Could not open codec" << std::endl;
    throw std::runtime_error("Could not open codec");
  }

  // Allocate frame and packet
  AVFrame *frame = av_frame_alloc();
  AVPacket packet;
  av_init_packet(&packet);

  // Read frames from the video stream
  while (av_read_frame(format_ctx, &packet) >= 0) {
    if (packet.stream_index == video_stream_idx) {
      // Decode video frame
      int ret = avcodec_send_packet(codec_ctx, &packet);
      if (ret < 0) {
        std::cerr << "Error sending packet for decoding" << std::endl;
        break;
      }

      while (ret >= 0) {
        ret = avcodec_receive_frame(codec_ctx, frame);

        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
          break;
        } else if (ret < 0) {
          std::cerr << "Error during decoding" << std::endl;
          break;
        }

        std::cout << "return value: " << ret << std::endl;
        std::cout << "frame->format: " << frame->format << std::endl;
        std::cout << frame->width << "x" << frame->height << std::endl;
        std::cout << frame->linesize[0] << std::endl;

        // Print basic frame properties
        std::cout << "Frame " << codec_ctx->frame_number
                  << " (type=" << av_get_picture_type_char(frame->pict_type)
                  << ", size=" << frame->pkt_size << " bytes) pts "
                  << frame->pts << " key_frame " << frame->key_frame
                  << std::endl;
      }
    }

    av_packet_unref(&packet);
  }

  // Free allocated resources
  av_frame_free(&frame);
  avcodec_free_context(&codec_ctx);
  avformat_close_input(&format_ctx);
  return "generateThumbnail: " + input_file_path;
}

void ThumbnailGenerator::read_video_frames(std::string input_file_path) {
  std::cout << "readVideoFrames: " << input_file_path << std::endl;

  // Open input file and allocate format context
  AVFormatContext *format_ctx = nullptr;
  int ret = avformat_open_input(&format_ctx, input_file_path.c_str(), nullptr,
                                nullptr);
  if (ret < 0) {
    std::cerr << "Could not open input file: " << input_file_path << std::endl;
    // char buff[256];
    // av_strerror(ret, buff, 256);
    // printf(buff);

    std::cerr << "Error: " << ret << std::endl;
    AVERROR(ret);

    throw std::runtime_error("Could not open input file");
  }

  // Retrieve stream information
  if (avformat_find_stream_info(format_ctx, nullptr) < 0) {
    std::cerr << "Could not find stream information" << std::endl;
    throw std::runtime_error("Could not find stream information");
  }

  // Find video stream
  int video_stream_idx = -1;
  for (unsigned int i = 0; i < format_ctx->nb_streams; ++i) {
    if (format_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
      video_stream_idx = i;
      break;
    }
  }

  if (video_stream_idx == -1) {
    std::cerr << "Could not find video stream" << std::endl;
    throw std::runtime_error("Could not find video stream");
  }

  // Get codec parameters and codec context
  AVCodecParameters *codecpar = format_ctx->streams[video_stream_idx]->codecpar;
  AVCodec *codec = avcodec_find_decoder(codecpar->codec_id);
  AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
  avcodec_parameters_to_context(codec_ctx, codecpar);

  // Open codec
  if (avcodec_open2(codec_ctx, codec, nullptr) < 0) {
    std::cerr << "Could not open codec" << std::endl;
    throw std::runtime_error("Could not open codec");
  }

  // Allocate frame and packet
  AVFrame *frame = av_frame_alloc();
  AVPacket packet;
  av_init_packet(&packet);

  // Read frames from the video stream
  while (av_read_frame(format_ctx, &packet) >= 0) {
    if (packet.stream_index == video_stream_idx) {
      // Decode video frame
      int ret = avcodec_send_packet(codec_ctx, &packet);
      if (ret < 0) {
        std::cerr << "Error sending packet for decoding" << std::endl;
        break;
      }

      while (ret >= 0) {
        ret = avcodec_receive_frame(codec_ctx, frame);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
          break;
        } else if (ret < 0) {
          std::cerr << "Error during decoding" << std::endl;
          break;
        }

        // Print basic frame properties
        std::cout << "Frame "
                  << codec_ctx->frame_number
                  // << " (type=" << av_get_picture_type_char(frame->pict_type)
                  << ", size=" << frame->pkt_size << " bytes) pts "
                  << frame->pts << " key_frame " << frame->key_frame
                  << std::endl;
      }
    }

    av_packet_unref(&packet);
  }

  // Free allocated resources
  av_frame_free(&frame);
  avcodec_free_context(&codec_ctx);
  avformat_close_input(&format_ctx);
}