The iPad screen has an aspect ratio of 4:3. 1080p video has an aspect ratio of 16:9.
I tried playing a 1080p video on the built-in player and got this:
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| | iPad | |
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where the outer border is the movie resolution (meaning, the video is getting chopped). I am a bit surprised that I couldn't find a mention of this anywhere online. Does the iPad really truncate 1080p videos by dropping pixels on the left/right of the frame?