1440 has a “PAR” – pixel aspect ratio. Meaning that each pixel has a shape, it isn’t square.
There are several dimensions that are non standard –
1440×1080 — 1280×1080 which both become 1920 when you multiply them by their respective PARs (1.33 and 1.5)
960×720 is an anamorphic version of 1280×720 (multiplied by 1.33)
In standard def, it’s the same way that the same dimensions (720×486 could become 16×9 or 4×3)…you don’t change the NUMBER of pixels, just the SHAPE.
This always creates an issue when played back in a media player, like Quicktime…because you are trying to interpret non-square pixels…and if that flag isn’t embedded correctly, it won’t play back right. It’s all about knowing what your source is and interpreting it correctly.
HTH,
-Jason