h264decoder_test1.cpp

#include <cstdio>
#include <cstdlib>
#include <stdexcept>
#include <vector>

extern "C" {
  #include <libavcodec/avcodec.h>
}

#include "h264decoder.hpp"

typedef unsigned char ubyte;


/* shamelessly copy pasted from
 * http://dranger.com/ffmpeg/tutorial01.html
*/
void SaveFrame(const AVFrame &frame, int iFrame) 
{
  const auto *pFrame = &frame;
  FILE *pFile;
  char szFilename[32];
  int  y;
  
  // Open file
  sprintf(szFilename, "frame%02d.ppm", iFrame);
  pFile=fopen(szFilename, "wb");
  if(pFile==NULL)
    return;
  
  // Write header
  fprintf(pFile, "P6\n%d %d\n255\n", pFrame->width, pFrame->height);
  
  // Write pixel data
  for(y=0; y<pFrame->height; y++)
    fwrite(pFrame->data[0]+y*pFrame->linesize[0], 1, pFrame->width*3, pFile);
  
  // Close file
  fclose(pFile);
}


static constexpr int file_read_size = 1024;


int main(int argc, char *argv[])
{
  H264Decoder decoder;
  ConverterRGB24 converter;
  disable_logging();
  
  std::FILE* fp = std::fopen(argv[1], "r");
  if (!fp)
  {
    fprintf(stderr, "cannot open file %s\n", argv[1]);
    return -1;
  }
  
  int frame_num = 0;
  std::vector<ubyte> framebuffer;
  std::vector<ubyte> buffer(file_read_size);
  for (;;)
  {
    int n = std::fread(&buffer[0], 1, buffer.size(), fp);
    if (n <= 0) break;
    
    auto const *data = &buffer[0];
    while (n > 0)
    {
      int num_parsed = decoder.parse(data, n);
      n -= num_parsed;
      data += num_parsed;
            
      if (decoder.is_frame_available())
      {
        const AVFrame& frame = decoder.decode_frame();
	//NOTE: pixel format of enum symbol named AV_PIX_FMT_YUV420P comes out of h264 decoder. 
	// This symbols happens to have numeric value zero. So it is no bug when frame->format == 0.
	printf("frame decoded: %i x %i, fmt = %i\n", frame.width, frame.height, frame.format);
	
	framebuffer.resize(converter.predict_size(frame.width, frame.height));
	const AVFrame& rgbframe = converter.convert(frame, &framebuffer[0]);
	
	++frame_num;
	if (frame_num < 10)
	  SaveFrame(rgbframe, frame_num);
      }
    } // while(n)
  }
  
  return 0;
}