Higher resolution or Higher Quantitizer quality?

[DaveScream]

Hello.
My source is 1920x1088. I tryed to encode it to x264 with original quality and Quantitizer set to 30 and get 1,53gb file size.
Also I tryed to resize it to 1280x720 with Quantitizer set to 25 and got almost the same 1,61gb

With equal file size how do you think what is better - higher resolution or higher quality?

I think higher resolution can give more sharpen picture... but what disadvantages?

[fredbe9300]

an interesting question. I've read once (don't remember where) that higher resolution should give the better result; but I that was many years ago in DIVX times - when people were downsizing way more... so (example) downsizing 720p to 480p vs 320p, there's a lot of detail lost in 320p... and doubt a little if that argument is still valid in a comparison 1080p vs 720p, both of which have a good amount of pixels for most of today's screens...

But you have the 2 output files, so it seems you have everything available to you to do a visual comparison? The result of which may differ (hypothetically) based on the chosen output device... artefacts noticed on laptop, may be less relevant on 32" tv if you sit at normal distance (3m), but relevant again on 50" tv (I'm just blabbing out loud, not sure about this).

A CRF of 30 is pretty darn high, so that might loose a lot of quality... so if your intended viewing device is not 1080p in resolution (e.g. many tablets aren't), than I would be indeed quite interested whether 720p at CRF-25 isn't better.

long story short: you tell us?

edit
up to a certain point, I believe that, for same total file size, higher res is better. But I also believe that this rule breaks at one point, when bit/pixel ratio becomes too low.

# disclaimer: I'm no professional, not even an amateur... but I have done quite a bit of downsizing to e.g. fit stuff on my tablet.

[fredbe9300]

by the way, I overlooked that you seem to talk about constant QP (quantization parameter), rather than CRF. Per the reading that i've done, CRF seems to result in better perceived quality at same file size.

e.g. here:
http://forum.doom9.org/showthread.php?p ... post760285
http://slhck.info/articles/crf

[flagpole]

yeah should deffo be using crf rather than CQ.

as for the original question. lord knows.