7 Replies Latest reply on Feb 1, 2010 8:48 PM by the_wine_snob

    Trouble converting 720p to 720x480

    ISTMAN

      Hello everyone.  I am very new to Premiere Pro and am trying to convert video shot at 720p in XDCAM EX format to NTSC 720x480 in DV widescreen format.  The video converts fine and looks great with exception to two vertical black lines on both sides of the video.  I see aspect ratio between the two videos are different and can not seem to get the correct settings to correct this.  I have tried zooming in as little as possible but when I do the video loses detail.  Any ideas where I am going wrong?

       

      Thank you,

      ISTMAN

        • 1. Re: Trouble converting 720p to 720x480
          Harm Millaard Level 7

          You are converting from square pixels to NTSC PAR.

          • 2. Re: Trouble converting 720p to 720x480
            ISTMAN Level 1

            Okay, thanks for the quick response.  Upon my brief google search of square pixels and PAR I can somewhat understand this.  However, I'm sure this issue must have been dealt with before.  Any suggestions on how to correct?  I would think part of the bottom and top of the frame would be cropped to allow the horizontal to encompass the entire frame.  Am I on the right track?  This is what I did when encoding with Adobe Media Encoder but again it just seemed to lower the detail drastically when compared to not cropping/zooming.

            • 3. Re: Trouble converting 720p to 720x480
              Colin Brougham Level 6

              Yep, you need to crop the top and bottom of the frame. Should be 8 pixels/lines off of both the top and bottom.

              • 4. Re: Trouble converting 720p to 720x480
                ISTMAN Level 1

                Just in case I did something wrong, I decided to re-convert a clip.  This time I verified 8 pixels off the top and bottom.  The preview in Adobe Media Encoder did worry me as the output definitely looked softer (less sharp, less focused) than the original.  I let it convert and compared the file to an identical uncropped version.  The difference is obvious.  The cropped file lost so much detail.  Why on earth is this happening?  I am going to a lower resolution on both files but they look so different. 

                • 5. Re: Trouble converting 720p to 720x480
                  Colin Brougham Level 6

                  Why on earth is this happening?

                  1. You're going from HD to SD.
                  2. You're going from progressive to interlaced scanning.
                  3. You're going from one framerate (23.976p, 29.97p, 59.94p) to another (29.97i).
                  4. You're using Adobe Media Encoder, which results in questionable quality on such exports.

                   

                  You can reduce but not eliminate some of the quality loss (at the expense of time) by using the Maximum Render Quality (MRQ) option in the encoder setup window. In the flyout menu (that tiny icon that looks like a stack of pancakes with downward-facing triangle), check that "Use Maximum Render Quality" is enabled. You should see somewhat better results, in approximately five times however long you waited for the original export.

                  • 6. Re: Trouble converting 720p to 720x480
                    ISTMAN Level 1

                    Colin, thanks for the info and tip.  I understand what you are stating, however, why is it the quality loss is so great when the frame is cropped by just 16 pixels?  If I do not crop and otherwise use identical compression settings the video looks great.  Cropped looks terrible.  With this I can come to the conclusion that statements 1 thru 4 are not pertinent because all settings are identical with exception to the slight crop.

                     

                    Oh, perhaps it is because with the extra 16 horizontal pixels being thrown out, the video is expanded both horizontally and vertically to fill the frame.  In that case, wouldn't it just be prudent to let the vertical black bars on either side just remain?

                     

                    Your statement in step 4 implies the possibility of using a different encoder; correct?  Would you suggest I transcode prior to importing to Premiere?

                     

                    Thanks for all of your help.

                    • 7. Re: Trouble converting 720p to 720x480
                      the_wine_snob Level 9

                      If you have not seen Jeff Bellune's HD to SD tutorials, this ARTICLE has some useful links. Be sure to go down-thread a bit, as I think that the URL might have changed.

                       

                      Hope that this helps,

                       

                      Hunt