4 Replies Latest reply on Jan 9, 2009 3:26 PM by Jonas Hummelstrand

    HD frame sizes and pixel aspect ratios

      I have 1920 x 1080 HD footage shot on the Canon 5D Mark II and trying to add some filters to it in AE and then render as a 1280 x 720 file. None of the DVC PRO HD presets seem to get me to this frame size and when I've rendered to that frame size the renders come out distorted, indicating to me that the pixel aspect ratio is off. The DVC PRO HD preset renders a 960 x720 movie. I've been told that these will play at 1280 x 720 but am nervous about this as the work is for an event and I don't want anything to go wrong. I can't figure out how to render a movie that has the right dimensions and the right pixel aspect ratio.

      One workaround seems to be to render at 1920 x 1080 and import it into Final Cut and make it 1280 x 720 there. But of course this is an extra step.

      Any advice out there? Thanks in advance,

      Loch
        • 1. Re: HD frame sizes and pixel aspect ratios
          Mylenium Most Valuable Participant
          I don't quite follow. Feel free to define a custom composition size as you see fit. Indeed AE does not provide presets for everything, but given the plethora of possible output targets, this cannot be the goal of such an exercise. You should only use the DVCPro preset, if you plan on roundtripping without modifying the resolution, i.e. writing the modified clips back to a tape with the same specs/ via the same deck. The more interesting question here is, whether the stuff will actually be played via such a deck on the event or if it e.g. will be output from a BluRay disc via a Playstation or something. In the latter case they'd probably even prefer it to remain at the original full HD res for output via HDMI without extra conversions, as the 960x res would be of no use to them...

          Mylenium
          • 2. Re: HD frame sizes and pixel aspect ratios
            Level 1
            Thanks and just got back from a test. What you say is dead on.

            I have a job yet to do however where I will have to take a variety of HD sources and combine them in AE and then output to 1280 x 720. I remain unsure about how to do this without having some distortion via pixel aspect ration and/or frame size problems. But I will try what you say, and output custom via Animation compressor and avoid DVC PRO HD presets altogether. That may just do it.
            • 3. Re: HD frame sizes and pixel aspect ratios
              Mylenium Most Valuable Participant
              While AE may not provide custom composition presets for everything, these problems should be covered correctly by the automatic footage interpretation. Therefore, your 960x720 pixel footage will be correctly "un-squeezed" when dropping it into a 1280x720 comp. Regardless of this, you can of course always enforce a different interpretation to correct any mix&match issues.

              Mylenium
              • 4. Re: HD frame sizes and pixel aspect ratios
                Jonas Hummelstrand Level 2
                Loch,

                If I'm not mistaken, the Canon 5D mkII shoots square-pixel 1920 x 1080 30p, so that's how you should interpret the footage. Just drop that into a comp with a 1280 x 720, square pixels at 30 fps and you're good to go.

                - Jonas Hummelstrand
                http://generalspecialist.com/