I'm working with footages that were shot on an Epic at 4K, 24fps, 16:9 aspect ratio. We transcoded them to ProRes LT 2K resolution. The frame size reads 2048 x 1152, which is a 16:9 aspect ratio. However, the standard size for 2K is usually listed as 2048 x 1920 (like on the AJA T-Tap's tech specs) which works out to be another aspect ratio.
Am I doing something wrong? Why is there this discrepancy?
2048 x 1152 is mathematically correct for the HDTV 16:9 (1.78:1) aspect ratio.
The DCI standard uses a 1.89:1 aspect ratio which equates to 2048 x 1080.
You are not doing anything wrong, it just depends on which "standard" you are going to follow.