6 Replies Latest reply on Sep 24, 2008 9:34 AM by Ann Bens

    Cropping (zooming) HD video for standard DVD

      I am making a standard DVD (480 scan lines) but using some 1080i HD video clips (.m2t files) from my Sony HD7E camcorder.

      I assumed that with the 1080i I could crop and zoom and still not lose any quality. 1080 / 480 is 225% by my math. I am only zooming 150% but the quality does not look good. I am getting jaggies.

      Is my assumption wrong?

      Or is PE4 down converting my clips when I import the .m2t files? If so can I prevent it?
        • 1. Re: Cropping (zooming) HD video for standard DVD
          Steve Grisetti Adobe Community Professional
          That's probably not the best way to use hi-def video to make a standard def DVD, born.

          The FAQs at the top of this forum tell you how to downsample your HDV to excellent, high-quality standard DV.
          • 2. Re: Cropping (zooming) HD video for standard DVD
            PeterFDuke Level 1
            This problem has been discussed before in several places, and the prevailing view is that PE (and PPro for that matter) does not do a good job of downsampling, particularly if you do some processing on the HD signal first.

            Downsampling in the camera is fine for straight conversion from HD to SD, but if you want to do things like panning and zooming, then you will certainly lose some quality if you do that on the downsampled signal.

            When you zoom in on a HD signal, you interpolate. Then when you convert that to SD, you interpolate again. Since we are dealing with interlaced signals, the interpolation has to be done on each field separately if there is motion in the video. Interpolation involves compromises which have the potential to degrade the quality.

            Some experimenters have claimed that the interlaced movie has to be converted to progressive before downsampling, but that may be based on the use of static test patterns rather than moving images.

            I used Mercalli stabilizer on a HD signal, zoomed in to crop off the resulting wobbly border, and converted to SD for a DVD. I tried a few of the recommended methods of doing the downconversion, and settled on using AVIsynth. I was still somewhat disappointed, but that was partly due the motion blur from using a hand-held camera. The motion blur is not so obvious in the context of a wobbly shoot, but when you remove all motion from the background, the motion blur stands out more.

            I haven't studied the subject lately to see what the experts currently recommend because I am still mainly working on SD source. I am hoping that the next release of video editors, including PE, will do a better job of downconverting HD to SD.

            I suggest you do a search on other forums to see what others think. Then try some of the methods yourself to see what works best for you.
            • 3. Re: Cropping (zooming) HD video for standard DVD
              Ann Bens Adobe Community Professional & MVP
              Zooming to crop footage always makes things worse. Better is to get yourself a tripod or even a string attached to the camera to act as a monopod instead of using Mercalli.
              • 4. Re: Cropping (zooming) HD video for standard DVD
                Level 1
                Thanks. I did use a tripod to shoot. My issue was getting a little closer. I mistakenly thought I could zoom in post-PE4 import. Anyway, I re-imported all my video from the camcorder with conversion to SD. The Sony HC7 has a "playback zoom" and so I was able to do an in-camera zoom during playback while importing into my computer as SD AVI files. Then used the AVI files to import into PE4 as suggested. The quality now is perfect! Thanks again!!!
                • 5. Re: Cropping (zooming) HD video for standard DVD
                  PeterFDuke Level 1
                  That's thinking outside the square! I never thought that playback effects in the camera would affect the exported video.
                  • 6. Re: Cropping (zooming) HD video for standard DVD
                    Ann Bens Adobe Community Professional & MVP
                    Sounds like digital zooming. Is also quality degrading, but down converting to SD will probably make it unnoticeable.