Video doesn't show while playing .mp4 files

[shiningwizard]

OK, so recently, I tried converting a .avi file to a .wmv format using Replay Converter (which, btw, I've uninstalled)... the size decreased drastically (from 350 MB to 20 MB) and I was like happy and all.. then I tried playing that file, but for some reason, the video never showed up.. I tried playing it in many players : Windows Media Player, Media Player Classic, WinAmp, Real Player. I opened the file in VirtualDub and I was able to see the video perfectly, though the other players were recognizing it as an audio file.

Now, the problem is that, I had downloaded videos from YouTube in .mp4 format, and for some reason, whenever I try to play these .mp4 files in the players mentioned above, the video doesn't show! It was working fine before I did the Replay Converter thing..... I have to resort to VLC Media Player now..

Also, whatever files I've downloaded from YouTube after this whole Replay Converter thingy, they're playing just fine in Media Player Classic (6.4) but when I try to play the older files (the ones I downloaded before the Replay Converter thingy) the video doesn't show for some reason. I can't figure out what could be wrong.

{I use Windows XP Professional SP2}

[poisondeathray]

You probably don't have the proper codecs installed.

VLC has internal codecs so it can play most things without installing extra codecs.

If you want to view what codecs are being used by that particular file, use mediainfo (view=>text)

If you install that specific codec, it should be able to be played on various software players. I can tell you right now ffdshow is probably the one you want installed.

Cheers

[shiningwizard]

I downloaded ffdshow and it works! Thanks a lot!