(ts to mpeg4) downscale during encode or playback?

[EjectButton]

this is a hypothetical scenario comparing playback of an mpeg4 video at a specific display resolution, I am wondering which would be a better option, downscale during encode or on the fly during playback by the software decoder.

(source material)-
1920 x 1080
mpeg2 transport stream
10gigs

(display)
fixed width of 1600


(option 1)
compress the transport stream to a 4.5gig xvid video
keeping the resolution at 1920x1080, so at playback the player (a computer) would have to downscale the video to 1600 on the fly

(option 2)
compress the transport stream to a 4.5gig xvid video
during compression also resize the video to 1600x900 so the resulting mpeg4 video will be the native resolution of the display


my question is are there any differences between these two options, other than the higher processor requirement for playing back a higher resolution mpeg4 video? would there be any perceivable difference?

[lazyn00b]

I've considered this problem myself because I have a front projector with non-HD resolution. My conclusion is that if you are archiving content for future use, it is better to retain the original resolution of the source material because there is always the possibility that you will acquire a higher resolution display in the future than the one have now. If you downscale during encoding, you will never be able to get back the detail you lost.

[EjectButton]

What you said is similar to my conclusion, thinking that in the future if I were to get a higher res display I would then be forced to upscale and put emphasis on a lack of resolution that I caused myself when downscaling.

I guess my only concern is the possibility that if I go from mpeg2(ts) -> mpeg4(xvid) and half the size I might have compression artifacts visible, especially a lack of sharpness, that might be less visible if the video was also downscaled at the time of compression.

I haven't been able to find any evidence of this yet (though I have been able to find little discussion on this particular topic). This might be a complete non-issue but I'm still unsure, mostly because of my lack of ability to find confirmation one way or the other in the form of guides, tests, or reviews.