5 Replies Latest reply on Nov 30, 2012 5:22 AM by will.reeves

    Settings to accurately "un-squash" PAL DV to square pixels




      I just wondered if anybody knew the settings to "accuratly" un-squash DV PAL widescreen video?


      I've "done the math" and the results just don't cut it.


      For example:


      The original DV is reported to be 720x576.  So using "square pixels" and a 16:9 aspect ratio, by rights the output size should be 576*(16/9) = 1024.  Settings:


      dv settings1.PNG


      However there are two issues here.  Firstly I get two thin black bands top and bottom of the image - so this is crazy since if the input video is 576 pixels and the output is also 576 pixels, why has Premiere Pro resampled in the vertical direction?


      I've noticed that by setting the width to 1054, I can make the black bands dissapear but this 3% difference in expected aspect ratio is very disturbing.


      Even then the resampling quality is poor.  My original video has a title on the screen (white on black - static and constant throught the video) here's a screen grab:




      The 1024 pixel wide version looks like this:



      Significantly worse I think you'll agree. Now some of this could be related to the H.264 compression but I suspect that most of it is due to unnescessary resampling artifacts in the vertical direction.


      Here's the 1054 width version (still 576 high):


      And for fun here's a 1052:


      Notice in all these examples how the horizontal "resampling" is being affected (especially bad in the 1054 version) and again note that I'm not changing the height at all!!!


      So my question is:  Why does changing the width of the target video affect the resampling in the height when I've specifically selected the exact height and switched off the "preserve aspect ratio lock"?  I think this is a bug.  This would not be a problem in Photoshop...


      Alternativly, please let me know where I'm going wrong and what settings I should use to preserve vertical resolution precicely, whilst stretching the width by a factor of 16/9.


      Thanks in advance for your help!