16:9 XviD resolution.

[pcroland]

Hi! I know that mod16 is important in XviD encoding, but I don't understand why 624x352 is the most used resolution at 16:9 ratio?
These are the AR errors for 16:9 resolutions:
720x400 1.23%
704x400 1.01%
688x384 0.77%
672x384 1.58%
656x368 0.27%
640x368 2.22%
624x352 0.28%
So why not 688x384 or 656x368?

[Bloax]

Because at 624x352 you have less pixels to squish into dat 700 MB CD? :-)

[pcroland]

I see that resolution in every XviD release of series. And those files usually have 300-400MB file size :D I think that nowdays no one really want to fit anything into a CD :D

[detmek]

No, but old habits don't go easily.

[mariush]

An explanation would be... because it's most likely pirated content ("scene release") and those are usually encoded following some "scene rules".

For example, see "XviD Releasing Standards 2005" : http://savedonthe.net/a/txd2k5.nfo.txt

Basically, release groups made some rules in order to "release" pirated content with a "guaranteed" minimal quality, otherwise each group would have used the fastest encoding settings possible to be the first group to release the pirated content and score virtual points and credit.
So as you can see in the text document, unless a group wants their release "nuked", they must follow some rules including these:



│ Movie Length: │
│ - PAL (25 fps) = MINIMUM runtime is 100 minutes/CD. │
│ - FILM (23.976 fps) = MINIMUM runtime is 105 minutes/CD. │
│ - NTSC (29.97 fps) = MINIMUM runtime is 87 minutes/CD. │
│ - These runtimes are scalable via the following equation: │
│ N CD time minimum = (N-1) * allowed time where N is number of CDs and │
│ allowable time applies to fps as outlined above: │
│ i.e. 3 CD FILM rip minimum = 105 x (3-1) = 210 minutes. │

³ Resolution and Aspect Ratio: ³
³ - Width: 512 - 672 pixels for WS movies (Letterboxed is considered WS). ³
³ 448 - 576 pixels for FS movies (Only 4:3 images). ³
³ - Height and Width: Must be a multiple of 16. ³
³ - Cropping is required to be the MAXIMUM possible (black borders must ³
³ be cropped to their maximum). Over cropped releases are considered ³
³ a technical flaw. Some movies present changing ARs, in that case the ³
³ cropping applies only to the image that presents more pixels (Means ³
³ that part of the movie will have bad cropping). ³
³ - Movie encodes must be within 5% of the original aspect ratio. ³
³ Calculating AR % error: (Release AR - Original AR)/Original AR x 100 ³


I hope mentioning this is not against the forum rules (I'm not promoting piracy or posting pirated content), and the document is public, available on the web.

[Sparktank]

http://i.imgur.com/r9ykpqd.gif (http://imgur.com/r9ykpqd) rule 6?
Seems to be more about pirating encodes rather than something personal (for personal encoding that dont' violate rule 6).