Yes avidemix is the video editor i have but haven't used it because i dont know how to. So you're saying that i need to convert my 1080p vids to 1440p at the bit rate of 30,000 right? Okay then what would be the the best video output format to set the bitrate that high? I was using Mpeg4 avc but couldn't find how to increase the bitrate. I can go to "filters" and then change the resolution.
And if you have a video to explaining the 3rd and 4th para that would be great. And yes my uploaded vid was indeed 1080p but it was way way blurry that the original. The chromatic effects of the gold skin effect is completely gone which is absolutely unacceptable.
But what about those videos i see on YouTube they post, is exactly the same quality how the GPU produces the picture quality.
Use Mpeg4 AVC (x264) as your codec, then in the Configure tab set Encoding mode to Average Bitrate (two pass), then set the Average bitrate box to 30,000. Since I use ShadowPlay to capture (usually on Instant Replay 20 min), I just leave Audio at Copy. Then set Output Format to Mp4 Muxer.
To resize under video output category click the Filters tab, scroll near the bottom and double click swsResize. In the Resize Dimensions boxes set Height to 1440. It used to then automatically put width at 2560 when Aspect Ratio is set to the default Lock Aspect Ratio, but now you have to manually set it for some reason. Just one click on the width box sets it to that though. Then in the Resize Method box I recommend Lanczos-3, as it's the sharpest. However it is best when using Lanczos-3 not to use ANY Nvidia Sharpening in NCP's Scaling options, otherwise you get ringing. If you prefer a bit softer look, use the default Bicubic for Resize Method.
You then only need to go to File>Save in Avidemux to save the compressed file as any name you want. If Avidemux starts playing out of sync badly or stops responding well to start and stop commands, this usually means it's cache is too full. To solve this problem, click Recent on the top tool bar, then Clear recent items. Another tip, is you can load your video clips way faster by just clicking Cancel on the little Encoding frame type window that shows when you open a video file, then click Yes.
I decided to show two videos of the same mission in Ghost Recon Wildlands, as after further checking I noticed there seems to be more visible difference when one video is uploaded at 1080p, and the other at 1440p. As I said before, YouTube will sometimes use VP9 processing on 1800p videos, and it could be they use it for that res when uploading a 1400p clip, though I'm not sure.
To get the best example of how these videos differ in sharpness, you'll need to view them both in fullscreen, preferably on a display that's not too small (mine is 32"). Set one to 1080p, the other to 1440p, not Auto. The difference is most noticeable in the last half of the mission where you're escaping on a road. You may also notice less difference here than with the compression method you were using, because Avidemux Average Bitrate using the Mpeg4 AVC (x264) codec at 30,000 bitrate produces very good results.
1080p Upload
1440p Upload
As far as your 3rd paragraph, if you mean why are some people's 1080p videos so good on YouTube, like I said, it's usually to do with how many views they get. Generally if you look at the views of the video and it's got like several hundred thousand views, YouTube will give it VP9 processing, because those videos are valuable ad space for them. This also means people getting lots of views can get monetary kickbacks from YouTube, but it can also mean the viewers have to put up with ads interrupting the viewing experience.
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