starting decoding frame and figuring out how to convert to png

src/Main.cpp

@@ -25,10 +25,14 @@ int main(int argc, char *argv[]) {
   std::unique_ptr<ThumbnailGenerator> thumbnailGenerator =
       std::make_unique<ThumbnailGenerator>();
 
-  int duration = thumbnailGenerator->get_duration(input_file_path);
+  int duration = thumbnailGenerator->get_duration_microseconds(input_file_path);
   std::cout << "duration: " << duration << std::endl;
 
   // thumbnailGenerator->read_video_frames(input_file_path);
 
+  std::string thumbnail_path =
+      thumbnailGenerator->generate_thumbnail(input_file_path);
+  std::cout << "thumbnail path: " << thumbnail_path << std::endl;
+
   return 0;
 }

src/ThumbnailGenerator.cpp

@@ -1,5 +1,7 @@
 #include "include/ThumbnailGenerator.hpp"
 #include <iostream>
+#include <libavutil/pixdesc.h>
+#include <libavutil/pixfmt.h>
 extern "C" {
 #include <libavcodec/avcodec.h>
 #include <libavformat/avformat.h>
@@ -35,9 +37,104 @@ int ThumbnailGenerator::get_duration_microseconds(std::string input_file_path) {
   return duration;
 }
 
-std::string ThumbnailGenerator::generate_thumbnail(std::string path) {
-  std::cout << "generateThumbnail: " << path << std::endl;
-  return "generateThumbnail: " + path;
+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) {