K-Lite Codec Pack 3.30 Full
Before installation:

It is highly recommended to first uninstall other codec related packages before installing this package. This way your system stays clean and potential problems will be avoided. This installer is able to automatically detect a lot of codec packs and it will ask you if you want to uninstall them.
Close all multimedia applications (media players, video editors, browsers, filesharing tools, etc) before installing this pack.

Installation:

Below on this page you can find some information about all components included in this codec pack. Please read this information thoroughly. Leave all settings in the installer at their default values if you don't know exactly what you should install. Do NOT simply select all components because you think that more means better. In fact, less is better. Many components are not selected by default since it is very unlikely that you actually need them. Click on the 'Print' button to open this documentation in Wordpad. That way you can view it during the entire installation procedure.

After installation:

It is recommended to run the Reset to recommended settings shortcut after the first installation. This should be done on all user accounts, except for the administrator account that was used to perform the installation. This will make sure all filters are correctly configured.

Unattended installation:

Run the setup with the command-line parameter -MakeUnattended to create an unattended setup. A wizard called "Unattended Install Maker" will appear. Follow the instructions given in the wizard.

Components:

#   means that ffdshow is able to decode the same format(s) as the marked component. So you don't necessarily need to install the marked component if you install ffdshow.
#   means that Media Player Classic is able to decode the same format(s) as the marked component. So you don't necessarily need to install the marked component if you install MPC and use it as your default player.

Player:

Media Player Classic [version 6.4.9.0+ | Mod by Casimir666 v1.0.9.0]
This is a full-featured player which has internal decoding support for DVD, MPEG-1/2, MP3, MP2, AAC, AC3 and DTS. It also has internal support for opening MP4, Matroska and Ogg containers. Media Player Classic is also capable of playing QuickTime and RealMedia content if those codecs are installed.

ffdshow:

ffdshow [revision 1371]
ffdshow is a very powerful DirectShow filter can decode various audio and video formats. For example: DivX, Xvid, MPEG-4, H.263, H.264, MPEG1, MPEG2, FLV1, FLV4, MJPEG, CinePack, VP3, huffyuv, Theora, AAC, AC3, DTS, MP1, MP2, MP3 and TrueAudio. When using ffdshow you don't need to install separate DirectShow filters for all of these formats.
ffdshow VFW interface
For encoding into various formats: MPEG-4, DV, H.263, Theora, MPEG-2, MPEG-1, MJPEG and a couple more.
extra plugins
ff_kernelDeint.dll, TomsMoComp_ff.dll, FLT_ffdshow.dll, ff_samplerate.dll

DirectShow video filters:

Xvid [version 1.1.3] #
For decoding Xvid video. This is currently the most popular video format.
DivX [version 6.6.1.4] #
For decoding DivX video.
CoreAVC [version 1.3.0.0] #
For decoding H.264/AVC video.
On2 VP6 [version 6.4.2.0]
For decoding VP6 video. This format is not very common.
On2 VP7 [version 7.0.10.0]
For decoding VP7 video. This format is not very common.
MPEG-2 (Cyberlink) [version 6.0.0.3402] # #
MPEG-2 (Gabest) [version 1.0.0.3+] # #
For decoding MPEG-2 video.
Cyberlink also support playback of DVD video in Windows Media Player and Windows Media Center.
Windows Vista (Home Premium / Ultimate) already contains its own MPEG-2 and DVD decoder. So you don't need to install one of these, unless you prefer them over the MS decoder.
MPEG-1 (MainConcept) [version 1.0.0.78] # #
For decoding MPEG-1 video.
Windows already contains its own MPEG-1 decoder. So you don't need to install this, unless you prefer it over the MS decoder.

VFW video codecs:

Xvid [version 1.1.3]
For encoding video in the Xvid format.
DivX Pro [version 6.6.1.4]
For encoding video in the DivX format.
x264 [revision 606]
For encoding video in the H.264 format. We don't recommend using the VFW system to encode H.264 video. It is better to use a CLI based solution, such as MeGUI.
On2 VP6 [version 6.4.2.0] [Encoding]
For encoding video in the VP6 format.
On2 VP7 [version 7.0.10.0] [Encoding]
For encoding video in the VP7 format.
Intel Indeo 4 [version 4.51.16.2]
For decoding Indeo 4 video.
For encoding video in the Indeo 4 format.
Intel Indeo 5 [version 5.2562.15.54]
For decoding Indeo 5 video.
For encoding video in the Indeo 5 format.
Intel I.263 [version 2.55.1.16]
For decoding I.263 video.
For encoding video in the I.263 format.
huffyuv [version 2.1.1 CCE Patch 0.2.5]
For decoding huffyuv video.
For encoding video in the huffyuv format.
huffyuv is a lossless (no quality loss) video compression format.
I420 (Helix) [version 1.2]
For decoding from and encoding in the I420 format.
YV12 (Helix) [version 1.2]
For decoding from and encoding in the YV12 format.

DirectShow audio filters:

MP3 (Fraunhofer) [version 1.9.0.311] # #
For decoding MP3 audio.
AC3/DTS/LPCM/MP1/MP2 (AC3Filter) [version 1.45b] # #
For decoding AC3 and DTS audio. Also decodes DVD audio.
Vorbis (CoreVorbis) [version 1.1.0.79] #
For decoding Vorbis audio. This is the recommended Vorbis decoder.
AAC (CoreAAC) [version 1.2.0.575] #
For decoding AAC audio.
MusePack (RadLight) [version 1.0.0.4]
For decoding MusePack audio files (.mpc).
WavPack (CoreWavPack) [version 1.1.0]
For decoding WavPack audio files (.wv).
OptimFROG (RadLight) [version 1.0.0.1]
For decoding OptimFROG audio files (.ofr .ofs).
DC-Bass Source [version 1.1.0]
This filter supports the following audio files: AAC (.aac .m4a) - Alac (.alac) - FLAC (.flac) - Monkey's Audio (.ape) - Tracker (.mod .it .xm .umx. s3m .mtm .mo3) - TrueAudio (.tta)
It also contains a source filter for .mp3 files that works a bit better than the default filter of Windows.
It also contains a source filter for SHOUTcast streams.

ACM audio codecs:

MP3 (Fraunhofer) [version 3.4.0.0]
MP3 (LAME) [version 3.97]
This can be used to decode/encode MP3 audio in applications like VirtualDub.
AC3Filter.ACM [version 0.4b]
This can be used to decode AC3 and DTS audio in applications like VirtualDub.
Vorbis [version 0.0.3.6]
Required for playing AVI files that contains Vorbis audio. These files are very uncommon.
DivX ;) Audio [version 4.2.0.0]
Some old DivX 3.11 videos use this audio codec.

DirectShow source filters:

AVI splitter (Gabest) [version 1.0.0.7+] #
AVI splitter (Haali Media Splitter) [version 1.7.189.11] #
For opening audio and video streams in a AVI container (.avi files).
MP4 splitter (Haali Media Splitter) [version 1.7.189.11] #
MP4/MOV splitter (Gabest) [version 1.0.0.3+] #
For opening audio and video streams in a MP4 container (.mp4 files).
Matroska splitter (Haali Media Splitter) [version 1.7.189.11] #
Matroska splitter (Gabest) [version 1.0.2.9+] #
For opening audio and video streams in a Matroska container (.mkv .mka files).
Ogg splitter (Haali Media Splitter) [version 1.7.189.11] #
Ogg splitter (Gabest) [version 1.0.0.0+] #
For opening audio and video streams in an Ogg container (.ogm .ogg files).
FLV splitter (Gabest) [version 1.0.0.2] #
For opening audio and video streams in a FLV container (.flv files).
MPEG PS/TS splitter (Gabest) [version 1.0.0.3 | revision 611] #
MPEG PS/TS splitter (Haali Media Splitter) [version 1.7.189.11] #
For opening audio and video streams in a MPEG Transport Stream container (.ts .m2ts .tp files).
For opening audio and video streams in a MPEG Program Stream container (.mpg .mpeg files).
The Haali MPEG PS splitter supports .evo files, however its support for regular MPEG files is currectly broken.
CDDA Reader (Gabest) [version 1.0.0.1] #
For opening CD audio tracks (.cda files).
CDXA Reader (Gabest) [version 1.0.0.1] #
For reading SVCD and XCD discs.
AC3/DTS Source (AC3File) [version 0.5b] #
For opening .ac3 and .dts files.

DirectShow subtitle filter:

DirectVobSub (a.k.a. VSFilter) [version 2.37 + fixes] # #
DirectVobSub is a filter for displaying subtitles (ssa/ass, srt and vobsub). Your subtitle file(s) should have the same filename as your video file (for example: MovieName.avi + MovieName.idx + MovieName.sub) and should be in the same folder as your video file. Then the subtitles will automatically be displayed in most players.

Tools:

K-Lite Codec Tweak Tool [version 2.1.0]
With this multi-functional tool you can (1) detect and fix some common problems (2) generate a detailed list of all installed codecs and filters (3) reset settings (4) backup/restore settings (5) manage the installed codecs and filters.
GSpot Codec Information Appliance [version 2.70a]
GSpot is a tool that can analyze AVI, MPEG and MP4 files and tell you which audio and video formats it contains. It can also perform a render test that shows you which filters are being used to play the file.
VobSubStrip [version 0.11]
With this tool you can strip languages from VobSub subtitle files (.idx and .sub files).
GraphEdit [build 041201]
GraphEdit is a visual tool for building and testing DirectShow filter graphs.
AVI Fixed [version 2.0b1]
This tool can rebuild the index section of .avi files. This can make files with broken frames playable. In some cases it will also solve synchronisation problems and incorrectly displayed movie lengths.
FourCC Changer
The FourCC (Four Character Code) Changer is a program for changing the FourCC of a video file, which is used to identify which codec should be used to decode the file. This tool is for expert users only.
Bitrate Calculator
This can be used to calculate the bitrate to use when encoding a movie.