C library to build video directly from buffers on Linux, preferably portable to Windows and Mac OS X

Question

I have a program that creates frame buffers in OpenGL. I can save out the buffers as .png or as .jpg files, and I am familiar with some utilities on Windows (like http://www.radgametools.com/bnkmain.htm) that will convert multiple image files to .mpg

But I would like an open source library to call with my buffer already in RAM. Does such an API exist?

Answer 1

Since you are looking for a library, I suggest taking a look at OpenCV (it's cross-platform library supported on Windows/Linux/Mac).

I've written the code below some time ago. It loads two JPG images from the current directory and creates a video file with it. I believe it's more than enough to get you started.

#include <cv.h>
#include <highgui.h>

int main()
{
    IplImage* img1 = cvLoadImage("img1.jpg", CV_LOAD_IMAGE_UNCHANGED);
    IplImage* img2 = cvLoadImage("img2.jpg", CV_LOAD_IMAGE_UNCHANGED);

    float fps = 20;
    CvVideoWriter* writer = cvCreateVideoWriter("out.avi", CV_FOURCC('M','J','P','G'), fps, cvGetSize(img1), true);
    if (!writer)
    {
      fprintf (stderr, "VideoWriter failed!\n");
      return -1;
    }

    cvWriteFrame(writer, img1);
    cvWriteFrame(writer, img2);

    cvReleaseVideoWriter(&writer);
    cvReleaseImage(&img1);
    cvReleaseImage(&img2);
}