Tutorial: Converting PNG into YUV Using FFmpeg or OpenCV C++ API

Sik-Ho Tsang
2 min readMay 12, 2020


FFmpeg & OpenCV

In this short story, I just want to mark down the way to convert PNG into YUV either using FFmpeg, or OpenCV C++ API. Of course, there are many ways to do it. (Sik-Ho Tsang @ Medium)

1. FFmpeg

1.1. Download FFmpeg

1.2. Convert PNG into YUV

  • To convert a PNG file into YUV, just simply enter below command with pixel format specified as YUV420:
ffmpeg -i 0001.png -pix_fmt yuv420p 0001.yuv
  • Then we can convert 0001.png into 0001.yuv.

2. OpenCV C++ API

  • As I need some manipulations during the conversion, so I also tried OpenCV C++ API.

2.1. OpenCV C++ API Installation

2.2. Convert PNG into YUV

  • First, include some headers:
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <iostream>
using namespace cv;
using namespace std;
  • Then, in the main function, to read the 0001.png, and also get the width and height of the image:
Mat image =  imread("0001.png");
int iHeight = image.size[0];
int iWidth = image.size[1];
  • And convert image into yuv by specifying COLOR_BGR2YUV_I420:
Mat yuv;
cvtColor(image, yuv, COLOR_BGR2YUV_I420);
  • Finally, estimate the buffer size for YUV420, write out the YUV buffer to file as 0001.yuv:
int bufLen = iWidth * iHeight * 3 / 2;
unsigned char* pYuvBuf = new unsigned char[bufLen];
File * pFileYuv;
fopen_s(&pFileYuv, "0001.yuv", "wb");
fwrite(yuv.data, sizeof(unsigned char), bufLen, pFileYuv);fclose(pFileYuv);
pFileYuv = NULL;
delete [] pYuvBuf;

During the days of coronavirus, let me have a challenge of writing 30 stories again for this month ..? Is it good? This is the 17th story in this month. Thanks for visiting my story..



Sik-Ho Tsang

PhD, Researcher. I share what I learn. :) Linktree: https://linktr.ee/shtsang for Twitter, LinkedIn, etc.