Quote:
Originally Posted by Robbie
I'm not sure if "cropping" is the right word, as I don't see anything missing. What I mean is if I crop a picture I remove some of it. When I encode the 720 x 480 AVI over to a 640 X 480 .mp4 using h264 compresson it doesn't crop anything off...it just seems to change the aspect slightly, and makes it look "correct" My understanding is that is simply the change in pixel shape which accounts for the difference of 80 pixels in width for the entire movie. I hope that makes sense, because I know I'm not communicating this in the correct technical terminology.
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The pixel aspect ratio of SD digital video is .9, so when you capture SD 720 x 480 footage you should always change the pixel aspect ratio to square pixels (1.0) for display on your computer monitor, which will result in a 640 x 480 frame size which can then be encoded into 320 x 240 video clips for example. I prefer to convert to square pixels when I encode my video clips from the edited DV AVI in a video encoding app like Cleaner XL.
On the other hand, HDV cameras record footage with a pixel aspect ratio of 1.333, so when you capture footage from your camera it will appear to be 1440 x 1080, until you convert it to square pixels, which has the opposite effect of the way the conversion from SD works and makes the frame size bigger. 1920 x 1080. Then one can one can encode to computer files like WMV or Flash or Quicktime in smaller multiples, most commonly 1280 x 720 or 480 x 270. Likewise, I do this when I encode the edited movie in an encoding app.