Encode video frame by frame in C++ using FFmpeg

Results of scientific or engineering simulations are often needed to be recorded on-the-fly. That is, the volume of data is often inapplicable to saving all individual frames on disk and postprocess them into video afterwards. This library leverages FFmpeg to embed video encoding directly into frame-producing application:

#include "movie.h"

#include <cstdio>
#include <vector>

using namespace std;

...

const unsigned int width = 1024;
const unsigned int height = 768;
const unsigned int nframes = 128;

MovieWriter movie("random_pixels", width, height);

vector<uint8_t> pixels(4 * width * height);
for (unsigned int iframe = 0; iframe < nframes; iframe++)
{
        for (unsigned int j = 0; j < height; j++)
                for (unsigned int i = 0; i < width; i++)
                {
                        pixels[4 * width * j + 4 * i + 0] = rand() % 256;
                        pixels[4 * width * j + 4 * i + 1] = rand() % 256;
                        pixels[4 * width * j + 4 * i + 2] = rand() % 256;
                        pixels[4 * width * j + 4 * i + 3] = rand() % 256;
                }

        movie.addFrame(&pixels[0]);
}

Additionally, the library offers an interface to encode SVG images.

Prerequisites

sudo apt install gcc-c++ cmake librsvg2-dev libx264-dev libgtk-3-dev

Building

git clone https://github.com/apc-llc/moviemaker-cpp.git
cd moviemaker-cpp
mkdir build
cd build
cmake ..
make -j12
./moviemaker-cpp_test

Acknowledgements

利用FFMPEG查看视频帧数的方法

ffmpeg -i "path to file" -f null /dev/null

or

ffmpeg -i 00000.avi -map 0:v:0 -c copy -f null -y /dev/null 2>&1 | grep -Eo 'frame= *[0-9]+ *' | grep -Eo '[0-9]+' | tail -1 

This work is largely based on original example on StackOverflow.