Free-Codecs.com :: Download audio and video Codec Identifiers (http://www.free-codecs.com/Software/Codec_Identifiers.htm)
除了AVIcodec 和GSpot 之外, MediaInfo (http://mediainfo.sourceforge.net) 在Codec 辨識上可說一點也不遜色, 尤其是對於MPEG4

補充:
YAAI - Yet Another Avi Info (http://www.free-codecs.com/download/YAAI_Yet_Another_Avi_Info.htm)
KC Softwares - VideoInspector (http://www.kcsoftwares.com/index.php?vtb)
FIX：當您在 Windows Media Player 9 或 10 中播放 MPEG4 影片時，可能會遭遇到模糊不清或是滲色的現象 (http://support.microsoft.com/kb/895181)

需要各種Codec 的網友, 請到Free-Codecs.com (http://www.free-codecs.com/Codec_Packs.htm) 尋找, 原則上, 參考網頁左下方 "MOST WANTED" 就對了, 建議安裝K-Lite Codec Pack Full (>18MB) (http://www.free-codecs.com/download/K_Lite_Codec_Pack.htm) 和Codec Installation Package for Windows Media Player 7.1 and later (1.35MB) (http://www.free-codecs.com/download/Codec_Installation_Package_for_Windows_Media_Player_7_8_9_10.htm) (或Windows Media Player 9 Codecs Pack (http://www.microsoft.com/windows/windowsmedia/forpros/format/codecdownload.aspx))

Free-Codecs.com :: The K-Lite Mega Codec Pack (>34MB) (http://www.free-codecs.com/download/K_Lite_Mega_Codec_Pack.htm), 這個Codec 包比K-Lite Codec Pack Full 還多了QuickTime Alternative, Real Alternative support 和Monkey's Audio DirectShow decoder 等等

豆芽菜看不懂的這有中文的
GSpot.exe Version 2.52 Build 040915
GraphEdt.exe [DirectShow SDK Filter Graph Editor] 檔案版本9.4.78.0
ffdshow語系檔 自行複製c:\....\K-Lite Codec Pack 2.7.6F\ffdshow\languages