[Ffmpeg-devel] DAR and SAR FFmpeg option confusion

[Trent Piepho]

On Tue, 13 Mar 2007, [utf-8] M??ns Rullg??rd wrote:
>
> You can't have SAR=10:11, DAR=4:3 and size=720x480, all at the same time.
> The maths simply don't work out.

There are two different sizes.  There is the size of the image, 720x480 in
this case.  And there is the displayed size, 704x480 is this case.  For
something like DV or a DVD, you have SAR=10:11, DAR=4:3, display size =
704x480, and image size = 720x480.

The DAR of 4:3 (or 16:9) doesn't refer to the aspect ratio of the entire
image, just to part of it.  You might say that it should be the entire
image, and that 4:3 is wrong in this case, but that's not what the
convention is.  Everyone says a 720x480 NTSC DVD is 4:3, not 15:11.  The
aspect code in the mpeg header is 4:3, there isn't any code for 15:11.