View source for PAK

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'''PAK''' file formats are package formats previously used by {{gldsrc|4}} engine games to store content. It was first introduced in {{quake|4}} engine which {{gldsrc|1}} subsequently adopted it. Unlike Quake, GoldSrc prioritizes loose files over those found in a PAK.

This was changed during the '''WON/Retail''' to {{steamicon|1}} transition in 2003, when the game files were stored inside [[GCF]] files located in {{path|...\Steam\steamapps\username\}} folder. Since the 2013 [[SteamPipe]] update, the game file have been stored directly to the filesystem (example: {{path|...\SteamApps\common\Half-Life\valve}}), as opposed to {{source|1}} and {{source2|1}} engines (which continued to packing game files inside multiple [[VPK]] files after SteamPipe transition) as most modern systems are fast enough to load {{gldsrc|1}} game files quickly.

As of today, the Steam version of {{hl|1}}, along with other {{gldsrc|1}} games are still able to load the {{path|.pak}} file despite longer being used to store vanilla game files.

{{important|PAK is often used as a generic file extension in the industry. PAK files used by other software, such as [[W:Google Chrome|Chromium]], [[Wikipedia:Unreal_Engine|Unreal Engine 4+]], or [[W:CryEngine|CryEngine]] are completely unrelated to the file format used by {{gldsrc|2}} and {{idtech2|2}}.}}
{{note|[[MP3]] files ''cannot'' be packaged in a PAK file. {{confirm|This might also be the case for [[WebM]], and formerly [[AVI]].}} }}

== Structs ==
{{license|type=gpl|version=2}}

{{w|C (programming language)|C}} code from {{file|common/qfiles|h}} in [https://github.com/id-Software/Quake-2-Tools/ the original Quake II development tools]:
<source lang=c>
#define IDPAKHEADER		(('K'<<24)+('C'<<16)+('A'<<8)+'P')

typedef struct
{
	char	name[56];
	int		filepos, filelen;
} dpackfile_t;

typedef struct
{
	int		ident;		// == IDPAKHEADER
	int		dirofs;
	int		dirlen;
} dpackheader_t;

#define	MAX_FILES_IN_PACK	4096
</source>
{{todo|Explain what the variable names mean, and how the structs are laid out in a PAK}}

{{important|{{code|MAX_FILES_IN_PACK}} is an engine limit, not a format one. The 2023 Kex remaster of {{quake2|2}} exceeds {{code|MAX_FILES_IN_PACK}}, and as such will not load in some tools such as {{pakscape|2}}.}}

== See also ==
* [[VPK]] - Package format used by {{src|2}} and {{src2|2}}
* [[HLLib]] - Library which can load PAK files
* {{vPKEdit|2}} - Program which can create and modify PAK files
* {{pakscape|2}} - Ditto
* [[PakExplorer]] - Ditto

[[Category:File formats]]