Now a days a wide range of video formats are available. common video file extensions are .3gp, .264, .3g2, .3gp2, .3gpp, .3gpp2, .3mm, .3p2,  .dat, .avi, .mpeg4, .mp4, .mkv etc., we can convert from one format to another format using audio and video converter software. Not only video format these software can also convert audio from one to another format.

According to my experience i suggest you to download some freeware software which are available from net. these softwares can convert  video and audio files from one format to another.

Free Studio	Free Studio is an all-in-one package bundling all free multimedia applications developed by DVDVideosoft. It is absolutely free and completly safe to install and run. With this free software you can easily convert video and audio files between different formats as well as ipod,psp, iphone, blackberry and and all popular mobile phones. burn to DVDs and Audio CDs Upload and download you tube videos and music to your computer, ipod,psp, iphone or blackberry Record videos and make snapshots. perform basic and editing of audio and video files. Supporting Operating System: Windows XP SP3, Vista, Windows 7 and .Net Framework 2 sp2, Official web site link: http://www.dvdvideosoft.com Download Software: Download Free Studio
Any-Video-Convertor	All-in-One Free Video Converter There is open source software to perform almost every task for video conversion. But if you are one of these windows users who are looking for an All-in-One video converting tool with easy-to-use graphical interface, Any Video Converter Freeware provides just that, allowing you to effortlessly convert video files for FREE! Free Video to Video Converter Whether you are looking for free AVI video converter, free mxf converter, free MKV video converter, free FLV video converter, free MP4 converter, free iPad converter, free Android converter, or free YouTube converter, Any Video Converter Freeware is the right application for you. Download the free video converter now to convert videos and experience better digital life.   Download link: Download,  AVC download Official Web site link: http://www.any-video-converter.com

About Media player:Media player is a computer software for play back  multimedia files. Most of the media players can play both audio and video files, Audio Files are .mp3,. Aiff, .wav, .au, .snd etc., and video files are .flv, .avi, .mkv, .mp4, .mpg, .wmv. .3gp, .swf etc., The most  popular and best media players (both audio and video) and their links are listed below.

Freeware

Name	Description
VLC media player	It is Simple, fast and powerful media player. It Plays most codecs with no codec packs needed:  MPEG-2, DivX, H264, MKV, WebM, WMV, MP3, Runs on all platforms: Windows, Linux, Mac OS X, Unix Official link http://www.videolan.org/ download: http://www.videolan.org/vlc/ for Windows  for mac os X and Other platforms External link download: http://www.filehippo.com/download_vlc_32/comments/ http://vlc-media-player.en.softonic.com/
K-Lite Codec Pack	K-Lite Codec Pack is a collection of DirectShow filters, DirectShow filters are needed for encoding and decoding audio and video formats. It is user friendly download from: www.freecodecs.com or www.freecodecs.com/download   http://www.filehippo.com/download_klite_codec_pack/
Windows Media Player 11 for XP   Windows Media Player 12 for windows 7	Windows Media Player for Windows XP offers great new ways to store and enjoy all your music, video, pictures, and recorded TV. Play it, view it, and sync it to a portable device for enjoying on the go or even share with devices around your home, all from one place. Official link www.microsoft.com windows.microsoft.com/download External link http://www.filehippo.com/download_windows_media_player/
Real Player	The easiest way to download & convert video or music in any format. Official link www.real.com External link www.filehippo.com/download www.softpedia.com/download
winamp	Winamp supports a wide variety of contemporary and specialized music file formats, including MIDI, MOD, MPEG-1 audio layers 1 and 2, AAC, M4A, FLAC, WAV, OGG Vorbis, and Windows Media Audio. Easily access the Media Library, Playlist Editor, Video, Visualizations, Media Monitor Browser, EQ, Skin Options and Color Themes all from one single user interface. Wireless desktop sync with winamp for  android, itunes library import, major podcast overhaul including new directory powered by mediafly, new windows7 support including taskbar player controls, availablein 16 languages, improved playlist generator, add winamp toolbar and control playback from browser. Official link http://www.winamp.com/ http://www.winamp.com/media-player/all External link http://www.filehippo.com/download_winamp/ http://www.softpedia.com/get/Multimedia/Audio/Audio-Players/Winamp-5.shtml
KMPlayer	The KMPlayer is a versatile media player which can cover various types of container format such as VCD, DVD, AVI, MKV, Ogg Theora, OGM, 3GP, MPEG-1/2/4, WMV, RealMedia, and QuickTime among others. Official link http://www.kmpmedia.net/ External link http://www.filehippo.com/download_kmplayer/ http://www.free-codecs.com/KMPlayer_download.htm http://www.softpedia.com/get/Multimedia/Video/Video-Players/KMPlayer.shtml

Latest versions of Media players: VLC Media Player 2.0.3 (32-bit), K-Lite Codec Pack9.20(Full), Windows media player 11 (XP), Windows media player 12 (win7), RealPlayer 15.0.6.14, XP codec pack, FFDShow MPEG-4 Video Decoder, LAV Filters, Koepi’s Xvid Codec, Divx8, DScaler MPEG Filters, Ogg Codecs, Xvid Video Codec 1.4-127, Ligos Indeo Codec 5.11, AC3 Filter 2.5b , AC-3 ACM Codec 2.2 , CoreVorbis 1.1.0.79,LAME DirectShow Filter 3.99.5, Fraunhofer MPEG Layer-3 Audio Decoder, Monkey’s Audio 4.10, Ogg Vorbis ACM Codec 0.0.3.6, KMPlayer 3.3.0.33, DVD Audio Ripper 7.4, winamp media player 5.63

Most popular website list to download media players:

• www.filehippo.com       (download all types of media players)
• www.free-codecs.com   (download video codecs, audio codecs, codec packs, and other tools)
• www.softpedia.com
• www.winamp.com

What is a Virus:

Virus (Vital Information Retrieved Under Seized) is a harmful program which are written by people (who wish to gain control of your system resources and are continually updated to try and break through any barriers you may have installed.)  perform different destructive functions. It may destroy programs and data .

Common Virus Infection Symptoms are

• Unexplained printing problems occur
• Operating System software appears to be modified
• The Keyboard does not work properly
• An entire disk or drive is erased
• Specific files are mysteriously deleted
• Unexplained messages appear on the screen
• Application software seems to be changed

The best way to detect virus is to use anti-virus software.

About Antivirus

Antivirus software  is designed to detect, prevent and removing malicious software like viruses, malware, worms, trojans etc., A virus signature is based on unique segment of code within the malware, typically checksummed/hashed and distributed in the form of antivirus signature updates.

The most popular Antivirus softwares and their link are listed below  (download always latest versions).

Freeware:

Name	Description
Avast Antivirus	avast! Free Antivirus is the best virus and spyware protection available. Download the world's most popular antivirus software completely free. Official link www.avast.com External Link http://filehippo.com/download_avast_antivirus/ http://www.avast.com/index
AVG Antivirus	Free antivirus and anti-spyware security software for Windows. Get free antivirus protection now! Official link www.avg.com External link http://filehippo.com/download_avg_antivirus_32/
Avira Antivirus	Avira offers best free antivirus protection against dangerous viruses, worms, Trojans and spyware Official link www.avira.com External link http://filehippo.com/download_antivir/

Premium Software

Symantec Endpoint Protection (Enterprise Edition)	Symantec Endpoint Protection is the fastest, most powerful endpoint security software solution. It provides state-of-the-art protection against all types of attacks through its network, file, reputation and behavior layers of defense. Symantec Insight makes scanning smarter resulting in dramatically better endpoint security performance. Endpoint Protection can integrate with VMware vShield Endpoint in virtual environments providing maximum performance without sacrificing security. Endpoint Protection seamlessly combines the essential endpoint security tools you need into a single, high performance agent with a single management console. Official link www.symantec.com http://store.symantec.com/ External link http://www.softpedia.com/get/Antivirus/Symantec-Endpoint-Protection.shtml http://download.cnet.com/Symantec-Endpoint-Protection/3000-2239_4-75133536.html
Norton by Symantec	Protect your small, medium or enterprise business with the latest security solutions from Symantec. Official link http://in.norton.com/antivirus/ External link http://in.norton.com/downloads/ http://www.softpedia.com/dyn-postdownload.php?p=4338&t=0&i=1
Kaspersky Internet Security	Kaspersky Lab is one of the fastest growing IT security vendors worldwide. Today it is firmly positioned as one of the world’s top four leading antivirus vendors*. Kaspersky Lab continues to further improve its market position, demonstrating higher growth rates than the market in general. According to the company’s 2011 unaudited financial results, Kaspersky Lab’s global revenue grew by 14% compared to the previous year and reached $612 million. Today it’s the world’s largest privately held vendor of endpoint protection solutions. Official link http://www.kaspersky.com/ External link http://www.kaspersky.com/trials http://www.softpedia.com/get/Antivirus/Kaspersky-Antivirus-Personal.shtml http://www.filehippo.com/download_kaspersky_antivir/ http://www.soft82.com/download/windows/kaspersky-anti-virus/
ESEC NOD32	ESET NOD32 Antivirus is the most effective protection you can find to combat today's huge volumes of Internet and email threats. It provides comprehensive antivirus and antispyware protection without affecting your computer's performance. official link www.eset.com http://www.esetindia.com/shop/home/ External link http://www.esetindia.com/shop/home/ http://www.filehippo.com/download_nod32/
Alwil Avast Professional Edition	Full-featured antivirus software with advanced virtualization technology. Any application can be run in the virtual desktop avast! Safezone. Official link www.avast.com External link http://www.avast.com/pro-antivirus http://www.softpedia.com/get/Antivirus/Avast-Professional-Edition.shtml

Other popular Antivirus for Home

Bit Defender  Antivirus	Award-winning antivirus software from Bitdefender. Get the best real-time security for your PC with our advanced software. Official link www.bitdefender.com http://www.bitdefender.com/Downloads/
Panda Antivirus	Harness the power of the cloud and help automatically improve the protection of every computer in the Panda community. Protect yourself from all kinds of online threats: viruses, hackers, online fraud, identity theft and all other known and unknown malware. Panda Global Protection Panda Internet Security Panda Antivirus Pro Official link www.pandasecurity.com http://www.pandasecurity.com/homeusers/downloads/ External link http://www.softpedia.com/get/Antivirus/Panda-Antivirus-Titanium.shtml http://www.scanwith.com/download/Panda_Antivirus_Pro.htm
Trend Micro	Trend Micro™ Titanium™ Antivirus+ provides easy-to-use security for the tasks you do every day—email, socialize, and surf the web, hassle free. It features: Antivirus and Antispyware, Antispam ,Security ,Social Networking,Windows 8 Secure Browser ,Fully compatible with Microsoft windows 8,Facebook Privacy Scanner Official link www.trendmicro.com http://downloadcenter.trendmicro.com/?regs=APAC
McAfee Virus scan	McAfee VirusScan Enterprise combines anti-virus, anti-spyware, firewall, and intrusion prevention technologies to stop and remove malicious software. Official link www.mcafee.com http://apac.trendmicro.com/apac/products/sb/ http://home.mcafee.com/downloads/free-virus-scan?ctst=1 External link http://www.filehippo.com/download_mcafee_virusscan/ http://mcafee-total-protection.en.softonic.com/
F-secure	F-Secure Internet Security is antivirus software that protects your computer against viruses and other malware and lets you browse the web safely. Official link www.f-secure.com http://www.f-secure.com/en/web/business_global/support/downloads External link http://www.scanwith.com/download/F-Secure_Anti-Virus.htm http://www.softpedia.com/get/Antivirus/F-Secure-Internet-Security.shtml

Latest versions of Antivirus:

Symantec Endpoint Protection Small Business Edition, Bitdefender Antivirus Plus 2013,Bitdefender Internet Security 2013, Bitdefender Antivirus for Mac, Bitdefender Sphere 2013, Bitdefender Total Security 2013, ESET Smart Security, ESET NOD32 Antivirus, ESET Cybersecurity, ESET Nod32 Antivirus for linux Desktop, ESET Mobile Security,Panda Antivirus 2013, Panda Internet Security 2013, Panda Global Protection 2013,Avast Antivirus 7.0.1466, Kaspersky Antivirus 2013.13.0.1.4190, AVG Antivirus 2012, F-Secure Anti-virus 2013, McAfee Total Protection 2013 , Trend Micro Antivirus plus Antispyware, Trend Micro Titanium Internet Security 2011, Trend micro Worry-Free Business Security, Trend micro  Worry-Free Standard Edition