How is a 1280×544 film considered to be 720p?
Horizontally, the picture is 1280 pixels, and this is the requirement of 720p. The “720p” tag is used for all frames of that size, whether they are 1280×720 or 1280×544, or any other height. Releases with these different dimensions have different aspect ratios or “degrees of widescreen”.
In the scene, instead of releasing them with black bars hardcoded into the video above and below the picture (known as matte), the releasers remove the ‘dead’ space for us. This results in a shorter image, and thus no wasted space, bandwidth or processing power. Also, for very wide screens, and fullscreen (non-widescreen) films, a matte might cause the picture to not even stretch the full width of the screen.