Selur's Little Message Board

I have a 1080p file of Trần Anh Hùng's Xích lô (Cyclo, 1995) that I would like to apply de-blocking to. The 123-minute feature has been compressed to 4.4 GB so I'd like to get as much blockiness out of the image as I can. Actually, compression artifacts aren't too bad. By glimpsing at the first reel, which of the following filters and settings should I try:

VapourSynth

1. Deblock
   
2. DeblockPP7
   
3. Deblock_QED
   
4. DPIRDeblock
   

AviSynth

1. Deblock
   
2. DeblockQED
   
3. amDCT
   
4. DeblockPP7
   

Also, do you think any debanding could be needed, too?

[/url]Here is the file:

[url=https://drive.google.com/file/d/1b4WF7AgGh5UIkahNtU9PXxfsA5oc24b2/view?usp=drive_link]https://drive.google.com/file/d/1b4WF7AgGh5UIkahNtU9PXxfsA5oc24b2/view?usp=drive_link

Personally I would try DPIRdeblock with high values like 75, 100, 150,...
I expect, conventional deblockers to either do nothing noticeable or blur too much.
You might also want to check BasicVSR++, 'NTIRE 2021 (1)' should perform well at such resolutions.
On some scenes, 'Video Deblurring (GoPro)' or 'Video Deblurring (DVD)' might also be worth a look, but probably will seem 'unnatural' in most scenes.
Another thing, independent of what deblocker you choose, might be to try testing what happens if you use CAS (0.7, 0.8.0.9, 1) before the deblocker.

Cu Selur

Ps.: In the future, use i.e. mkvtoolnix to cut yoru source and only share a chuck of it.

Ah, thanks very much for the quality suggestions and recommended settings, Selur! 

So, if I understand you correctly, I should first run CAS and then DPIRdeblock, right? (If I chose to execute that combo.)

Gotcha! Yeah, I'll just post selected clips on Google Drive.

I have the latest version of MKVToolNix installed on my ASUS but haven't done any editing with it before. So I can trim and cut scenes with it? Do you know which section/feature performs editing in the app? I'll have to peruse its documentation.

On remuxing MKVtoolnix allows to Split by size other criteria.
It also can Split by a given time, but will only cut on key frames

Cu Selur
Ps.: Here is an example of a. a cut of the file you linked b. a reencoded version where I used cas 0.9 and BasicVSR++.