есть ещё более простой способ ! для тихой установки KLiteMegaCodec131.exe - импортируем в реестр с ключом S
Код:

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\KLiteCodecPack_is1]
"Inno Setup: Setup Version"="5.1.3-beta"
"Inno Setup: App Path"="C:\\Program Files\\K-Lite Codec Pack"
"InstallLocation"="C:\\Program Files\\K-Lite Codec Pack\\"
"Inno Setup: Icon Group"="K-Lite Codec Pack"
"Inno Setup: User"="ANDY"
"Inno Setup: Setup Type"="custom"
"Inno Setup: Selected Components"="player,player\\bsplayer,player\\mpclassic,player\\mpclassic\\settings,video,video\\divx,video\\divx\\dec,video\\divx\\enc,video\\xvid,video\\xvid\\dec,video\\xvid\\enc,video\\3ivx,video\\3ivx\\dec,video\\3ivx\\enc,video\\wmv9vcm,video\\wmv,video\\vp3,video\\vp6,video\\vp6\\dec,video\\vp6\\enc,video\\indeo,video\\indeo\\5,video\\indeo\\4,video\\indeo\\32,video\\i263,video\\huffyuv,video\\msmpeg4,video\\divxmpeg4,video\\dvd,video\\mpeg2,video\\mpeg2\\splt,video\\mpeg2\\splt\\ec,video\\mpeg2\\dec,video\\mpeg2\\dec\\lg,qt,qt\\codec,qt\\codec\\browser,qt\\codec\\plugins,qt\\directshow,real,real\\codec,real\\codec\\browser,real\\directshow,audio,audio\\mp3,audio\\wma,audio\\ac3,audio\\ac3\\boostvolume,audio\\ac3acm,audio\\vorbis,audio\\aac,audio\\3ivx,audio\\3ivx\\dec,audio\\3ivx\\enc,audio\\musepack,audio\\voxware,audio\\ape,audio\\divxwma,audio\\mp3lame,filters,filters\\mp4,filters\\ogg,filters\\ogg\\oggds,filters\\matroska,filters\\matroska\\gabest,filters\\matroskamuxer,filters\\vsfilter,filters\\matrixmixer,filters\\shoutcast,filters\\mmswitch,filters\\dcdsp,ffdshow,ffdshow\\keepconfig,ffdshow\\vfw,tools,tools\\gspot,tools\\sherlock,tools\\vobsubstrip,tools\\fourcc,tools\\minicalc,compat,compat\\dshow"
"Inno Setup: Deselected Components"="video\\mpeg2\\splt\\mc,video\\mpeg2\\splt\\lg,video\\mpeg2\\dec\\cl,video\\mpeg2\\dec\\mc,real\\clearsettings,filters\\ogg\\gabest,filters\\matroska\\haali,ffdshow\\newconfig,ffdshow\\newconfig\\all"
"Inno Setup: Selected Tasks"="icons,icons\\bsplayerdesktop,icons\\bsplayerquicklaunch,fa_mpc,fa_mpc\\avi,fa_mpc\\mpeg,fa_mpc\\wmv,fa_mpc\\ogm,fa_mpc\\mkv,fa_mpc\\mp4,fa_mpc\\qt,fa_mpc\\real"
"Inno Setup: Deselected Tasks"="icons\\mpcdesktop,icons\\mpcquicklaunch,checknews"
"DisplayName"="K-Lite Mega Codec Pack 1.31"
"UninstallString"="\"C:\\Program Files\\K-Lite Codec Pack\\unins000.exe\""
"QuietUninstallString"="\"C:\\Program Files\\K-Lite Codec Pack\\unins000.exe\" /SILENT"
"DisplayVersion"="1.31"
"NoModify"=dword:00000001
"NoRepair"=dword:00000001