+ char buffer[256];
+ snprintf (
+ buffer, sizeof(buffer),
+ "video_size=%dx%d:pix_fmt=%d:frame_rate=%d/%d:time_base=1/1:pixel_aspect=1/1",
+ _size.width, _size.height,
+ _pixel_format,
+ _frame_rate.numerator, _frame_rate.denominator
+ );
+ return buffer;
+}