DVD opening modes - CellWalk, CellTrim, CellFull

[mike admin]

Starting from version 1.17.0 MakeMKV has a new DVD processing engine. When MakeMKV opens a DVD disc, it can do it using one of 4 modes (set in preferences on DVD tab) - Auto(default), CellWallk, CellTrim, CellFull. In a perfect world (in practice when opening a simple disc without any structure protections) all modes provide the same result. The differences arise when opening any modern commercial DVD with structure protection. In each mode MakeMKV uses different approach to distinguish "real" titles from "fake" ones. Each mode has its own benefits and drawbacks. As of now, with version 1.17.0 and beyond, the "Auto" is a very sane default one should rarely override.

Below is description of every mode.

CellWalk - The program emulates a DVD player. A virtual monkey sits before a virtual player, selects every menu, presses every button, watches everything, and records every title that was played. Doing so it marks every title with a comment consisting a letter and a number. The letter describes menu level, and the number - the button pressed in such menu. For discs with a "standard" menu - "1:play title, 2:scene selection, 3: special features, ..." the "A1" or "B1" would be assigned to the main movie (and related trailers). For series disc the episodes are usually easily distinguishable as well. The only drawback of this mode (aside from the case when it fails due to a bug) is that the program opens only accessible titles. Any well-hidden special features, that one cannot open from a DVD player menu would stay hidden as well. These are, however, very rare.

CellTrim - A blunt crowbar approach. The program tries to open every possible title (including all fakes), and trims junk content from the beginning and the end of a title. This method picks all possible content from the disc, but often produces a lot of useless content. No comments are assigned to titles. This was the main mode of operation before 1.17.0 .

CellFull - Run a CellWalk, and then run a CellTrim on all titles not referenced by a CellWalk . This extracts absolutely all content from a disc. In 99.99% the additional content would be just fake titles, however.

Auto - run CellWalk, and only if it fails for any reason, run CellTrim .

UDATE 13.07.2022: Very few discs still may hang in "Scanning Contents" phase when using Auto mode. Starting from 1.17.1 pressing the "Cancel" icon and confirming "Are you sure to cancel the current operation" would cancel just the scanning phase, not entire disc opening process. So, if the program hangs at this phase, pressing "Cancel" would abort the CellWalk scan and automatically switch to the CellTrim for the current disc.