Why does the Blu-ray specification only allow for a fixed set of resolutions instead of defining an upper bound on resolution? If arbitrary resolutions were allowed it would solve two problems:

  1. Double letter boxing or window-boxing. This happens when a movie has hard borders and the aspect ratio of the viewing device does not match the aspect ratio of the video.

  2. Certain movies were mastered at resolutions not in the list of allowed resolutions. This would avoid the need to resample the video which either results in a reduction in resolution or having to store upscaled video which wastes space.

Blu-Ray players already need to upscale or downscale the video to match the resolution of the device it's plugged into so I don't see any reason for not allowing this.

If the reason for not doing that is complexity, what about a fixed horizontal resolution and an arbitrary vertical resolution with an upper bound? That should be very simple to do because the player won't need to change how it upscales or downscales video it would just need to center it.

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    I’m voting to close this question because it would seem to fall under the heading of Technology questions about playing content which are specifically off-topic
    – Paulie_D
    Jul 31, 2020 at 10:11
  • @Paulie_D Thinking this over could the issue be that the rule needs to be clarified or in actuality means "Technology questions about how to playing content"? Under the current rule I guess this could be debatable but if there rule were changed to add how to play content we could still avoid having low quality questions such as "how do you use Windows Media Player?" while allowing for discussions regarding things that impact everyone who is interested in home video. Aug 2, 2020 at 9:04
  • 1
    The issue here is that this is not a Movie/TV question...it's a technology question. M&TV is primarily about appreciation of the actual show and it's production rather than the technology in showing it on screen. As to your question this is something that should be addressed to the spec writers rather than here.
    – Paulie_D
    Aug 2, 2020 at 10:22


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