[В гугле забанили] Примеры кодирования в theora

// Преобразование изображения в jpeg (~11 мс полный кадр)
void stream_jpeg(FILE *fp, char *data, int width, int height, int jpeg_quality){
        struct jpeg_compress_struct cinfo;
        struct jpeg_error_mgr jerr;
        int i,nc;
        unsigned char *line = data;
        if(jpeg_quality<10 || jpeg_quality>100) jpeg_quality = JPEG_QUALITY;
        nc = 1;
        cinfo.err = jpeg_std_error(&jerr);
        jpeg_create_compress(&cinfo);
        jpeg_stdio_dest(&cinfo, fp);
        cinfo.image_width = width;
        cinfo.image_height = height;
        cinfo.input_components = nc;
        cinfo.in_color_space = JCS_GRAYSCALE;
        jpeg_set_defaults(&cinfo);
        cinfo.JFIF_major_version = 1;
        cinfo.JFIF_minor_version = 2;
        jpeg_start_compress(&cinfo, TRUE);
        for (i = 0, line = data; i < height; i++, line += width*nc)
                jpeg_write_scanlines(&cinfo, &line, 1);
        jpeg_finish_compress(&(cinfo));

}