# File type .COS2 ?



## oldjoe (Aug 8, 2004)

Does anyone have a clue about .COS2 files that appear mysteriously?
Each file is 7KB in size.
Each has a file name matching a valid file name which exists in the same folder.
The valid files are all .wma or .wmv files.

Does anyone know what is generating these files, and for what purpose?

Should I just delete them?

Thanks,
OldJoe


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## calvin-c (May 17, 2006)

Google 'cos2 file extension'. It appears to be some Java cryptography stuff which I'm guessing is tied in with DRM. (I tried to read thru the document google linked too but frankly, I got lost. I'm not that good with cryptography.)

If you want to, delete one from an unimportant file & see if it still plays-then see if it re-created it when it played. It might be a digital signature, or it might be a license key, or it might be something else.


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## oldjoe (Aug 8, 2004)

Calvin.

Thanks for the reply. I accept the JAVA explanation, but I fail to see how JAVA got involved with these media files. I deleted one as you suggested, and the associated wma file played fine without it (using Windows Media Player 9.0), and the cos2 file was not regenerated. I'm still scratching my head... I will try other players too...
(Such as Nero and Pinnacle which I had been using with these media files)

OldJoe


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## Couriant (Mar 26, 2002)

Where are the COS2 files showing? I don't see a valid extension to COS2.


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## oldjoe (Aug 8, 2004)

Some added information:

Even after I have deleted these files, they get recreated the next time that I open the Pinnacle Studio 10.8 program that I use to edit movies.

I tried writing to Pinnacle about this, but the "contact us" part of their website is too complex for me to bother with...

While seemingly harmless, I would still like to stop this from happening.

Any tips ???

OldJoe


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## Couriant (Mar 26, 2002)

maybe it's their temp files... it's the only thing I can think of.


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## tony7896 (Jan 11, 2008)

I have many WMV files from the same source, and only a few have these matching files. I may have used Pinnacle to edit these files, so I think Pinnacle generates them. Maybe some kind of meta-data or index files.

My WMV files are not protected. I don't think it has anything to do with that.

I deleted them and it didn't affect how they played.


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## oldjoe (Aug 8, 2004)

Tony,
Thanks for your input. I agree with your theory, but I would like to read Pinnacle's comments about this. If anyone has a contact, please ask them...

OldJoe


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## carldouglas (Apr 21, 2008)

hi all I have cos2. files on my pc too and use pinnicle studio as well, and after reading this forum i sent pinnicle an email, i will let you know what happens, or doesn't, but i will try and get a difinitive answer for you.


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## oldjoe (Aug 8, 2004)

Thanks, Carl. Please let us know if you find an answer. I'm still curious. The files are small and seem to be harmless, so I've been ignoring them. Deleting them causes no problem either, but they reappear after some future use of Pinnacle... 

OldJoe


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## carldouglas (Apr 21, 2008)

there is another train of thought here but it isn't connected in any way with Pinnicle.
The thought is, as they appear in album folders on my pc, and as you say they come back could they be something to do with internet album information, the files that make up track names in media player, this just a theory at the moment and when of if i actually pin it down i will let you know.


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## carldouglas (Apr 21, 2008)

These files are as correctly stated automatically generated when you launch studio in Edit mode, studio picks up where it left off and the cos2 files are markers/backup files, so they will automaticaaly return each time you delete them if you are still working on that project. 

I am getting them in the folders/albums of the music I am using, presumably once you have finnished the project and either written it to disc, or moved the file to another drive, it should stop happening for that film/project. you can then go around and tidy up so as to say 

There isn't a cure as such yet! though pinnicle isn't doing anything wrong except being a little untidy

hope this helps

Carl


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