Audio and Video files require the correct filters,and codecs installed on the computer for playback.If you are also trying the backup your DVD or converting a video for playback on mobile devices like iPad, iPhone etc., you need the exact codec installed on your machine for proper conversion.
Read about 3 Audio – Video Converters For Conversion, Encoding, Ripping Audio and Video Files.
Sometimes to be able to preview media files the codec required to play the files need to be available on the system, Here’s are 2 codec packs 
- KLite Codec Pack – The K-Lite Codec Pack is a collection of DirectShow filters, VFW/ACM codecs, and tools. Codecs and DirectShow filters are needed for encoding and decoding audio and video formats.It has 5 variants right from the basic pack aimed at general playback support for AVI, MKV, MP4, OGM, and FLV formats and the higher end version mega pack which also has contains Real Alternative and some extra VFW/ACM codecs.
Codec Pack : Basic, Standard and Full. Check out the complete list of differences in the packs here.
K-Lite Codec Pack Basic contains only the most essential things. It contains everything you need to be able to play the most popular and widespread formats. It is small enough to fit on a single floppy. Also great for including on your movie CDs.
K-Lite Codec Pack Standard contains everything you need to play all the commonly used formats. This package should be enough for the average user.
K-Lite Codec Pack Full contains even more codecs. It also has encoding support for the various formats. This package is for power users and people who do their own encodings.The installation is fully customizable, allowing the user to install just those components that you really want and the un-installation is also clean removing all traces of the pack even from the registry.
KLite Codec pack is compatible with Windows 2000, XP, 2003, Vista, and Windows 7. - Combined Community Codec Pack – CCC Pack is a filter pack that install a wide range of codec and containers for playback on Windows irrespective of the codec used to make the video.It also comes with a media player Media Player Classic – HomeCinema (MPC-HC) along with the installer, so the end user does not even need to worry about the media player to use.It supports Windows XP, Vista and Windows 7 and also has a extended version for the MAC OS.
Here’s a list of formats for which CCCPack enables playback.
- Containers:
- AVI – including multiple audio streams and softsubs
- MKV
- MP4 – including partial MOV support
- FLV (Flash Video container)
- TS (MPEG Transport Stream)
- 3GP
- OGM & Ogg
- Video codecs:
- MPEG-1 – comes with Windows
- MPEG-2 – including DVD playback
- MPEG-4 ASP
- Xvid
- DivX (all versions)
- Generic/Others (3ivx, lavc, etc.)
- MPEG-4 AVC – better known as H.264
- WMV & VC-1
- VP6F (Flash Video)
- Theora
- H.263+
- Audio codecs:
- MP3, MP2 and MP1
- AC3
- DTS
- AAC
- Vorbis
- FLAC
- TTA
- WavPack
- AMR
- LPCM
- IMA ADPCM
- Subtitle formats
- SRT
- Vobsub (.idx + .sub)
- SSA / ASS
Note : Both the Packs cannot be installed at the same time, as that could lead the incompatibility of audio and video codecs and filters.
