# Can't play MP4s



## Janglur (May 23, 2010)

I donno why, but NOTHING will play an MP4, all of a sudden.

I reinstalled, uninstalled and reinstalled, KLite Codec Pack
Tried VLC
Winamp
Media Player Classic

All the same.  Black or no video, but audio plays.  WTF!?


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## Usarise (May 23, 2010)

Have you tried iTunes?  Its able to play and convert mp4s.


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## Janglur (May 23, 2010)

I would really rather not.  If it won't play in three different players, the problem is either the codec or something else, not the player.

It should be noted that ALL my MP4s are doing this.  No exceptions.


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## Smelge (May 23, 2010)

Go into the options for your media players, you can normally select what formats will play. Maybe MP4 has just dropped off.

Failing that, run a virus scan. Maybe there's an odd but very specific virus out there.


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## Taralack (May 23, 2010)

Try a different codec pack? I use CCCP and so far it has never given me problems.


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## Janglur (May 23, 2010)

CCCP and K-Lite are the same.  K-Lite contains CCCP.  It's part of the FDDShow grouping.

Regardless, it's not a problem with the codec.  The same codec played fine before, and now it doesn't, even after a reinstall.
I firmly beleive that it is something else.  Things don't just break without experiencing a change of some sort.


The question now, is...
What Microsoft file broke now!?


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## Smelge (May 23, 2010)

You could run a registry checker. See if anything is up in the main files.


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## Runefox (May 23, 2010)

Players like VLC come with their own codecs that aren't registered with the system, and they're entirely stand-alone, so even if something took out the system-wide codecs, VLC should still be able to open everything it could before.

One possibility (if other MP4 files that used to work now fail) is that your video drivers might need to be reinstalled if you're getting audio but no video.


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## yak (May 24, 2010)

What Runefox said.
Most modern video cards have onboard hardware decoders, and most modern player make use of those.


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## Ames (May 24, 2010)

Or you could just convert all your MP4s to another format.


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## Janglur (May 26, 2010)

Since everyone keeps suggesting it, I went ahead and tried to convert the MP4s.  They failed to convert-  the output file is the same.  (However all players will try to play the video.  Winamp wouldn't show a video screen, behaving like an mp3, while all the others (VLC, MPC) would play a blank black video screen.  After conversion, winamp tries to play a blank black video screen.)

This suggests that something IS preventing the MP4s from getting through.  However, I sent a couple of my files to a friend, and they play fine on their computer.  So i'm stumped.

I've reinstalled the drivers twice, and also tried third party ATI drivers.  Also tried older drivers.  No difference (except the third party drivers made my games look wierd.)  I've reverted back to the latest ATI drivers.

I'm going to remove my videocard and try the onboard video and see how that works.  I'll keep you posted on the results.


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## Runefox (May 26, 2010)

Out of curiosity, if you disable hardware acceleration / video overlay support in the players of your choice, does that make any difference?


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## Janglur (May 28, 2010)

Nope.  =/

I'm completely stumped on this.


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