[MPlayer-users] .wma audio fails to play - an example
raphael at clifford.net
Sun Jul 27 19:26:39 CEST 2003
GS HUNT wrote:
>[Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
>On Sunday 27 July 2003 07:13 am, Raphael Clifford wrote:
>>[Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
>>Dominik Mierzejewski wrote:
>>>[Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
>>>On Friday, 25 July 2003, Raphael Clifford wrote:
>>>>Here is the example audio file that does not appear to be playable under
>>>>linux. You have to unzip it to even get to the .wma file even though
>>>>under windows there is no need to as Media Player seems to understand
>>>>If we could find some way to play these files that would a fantastic
>>>>step forward. At the moment it seems that you can't play a lot of music
>>>>you have bought and downloaded online!
>>>It's a zipfile containing another zipfile (with some graphics), an asx
>>>playlist and wma audio, which doesn't play a sound. :(
>>Yep. The .wma is protected in some way. If you play it in Windows it
>>first "individualises" your media player by going to Microsoft over the
>>net and then asks for some personal details before doing something else
>>over the net that I don't really understand. You can then play it. I
>>can't find any details on the web of what exactly is going on. Does
>>anybody have any? Somebody must have a spec for .wmd files??
>>In the meantime I have the following basic questions:
>>Is the .wma actually encrypted requiring a key that is not in any of the
>>files in the .wmd archive? In other words, is it both theoretically and
>>practically impossible to play it without getting the key over the net
>>the way media player does?
>>Given that you have bought and paid for the track can we capture the
>>traffic that media player takes part in to get that key?
>>What is the encryption algorithm?
>If that wmd files is anything like files @ www.buymusic.com... then it's DRM
>(digital rights media) wrapped *encrypted* (Best of luck playing it on
>anything but WM9) (Mind you I'm sure we could but I don't want to support
>this horrible breach of privacy and freedom)
>I'm going steer clear of any files as such...I don't want Micro$oft and other
>companies watching everytime I play a tune, and regulating to what, where
>and how many times I can copy a song I have payed for..
>Don't feed the Beast...
>excerpts from http://emusician.com/ar/emusic_digitalrights_debate/
>WHAT IS DRM?
>In a nutshell, DRM limits access to the contents of a file to those who have
>proper authorization (that is, people who legally purchased the track), and
>it controls how the content can be used once it has been opened. The
>perception that that's the entire scope of DRM - which would then be more
>appropriately called digital-rights enforcement - has fostered a resistance
>to DRM on the part of artists and audiences that often borders on open
>In some DRM implementations, the security of the file can be circumvented
>without having to break its encryption. When a DRM-enabled media player has
>unlocked a media file, the music still must be transferred from the
>application to the computer's audio card. During this transfer, your music is
>unencrypted, uncompressed, and completely unprotected. Third-party tools and
>plug-ins have started to pop up on the Internet that can grab the contents of
>your file and make a perfect digital duplicate that can be shared without
>hindrance or compensation.
>The first response to this situation is Microsoft's Secure Audio Path (SAP),
>which was introduced in Windows ME and XP. When a DRM-wrapped file is opened
>on either of those platforms, SAP adds cryptographic noise to the signal that
>is removed at the computer's audio subsystem only when all of its components
>have been authenticated. If a copy of the file has been grabbed between the
>media player and the audio card, it contains noise that makes playback
>unlistenable. Playback by an authorized system is noise free, making SAP
>transparent to the authorized listener.
Thanks for the info.
Just for the record my suggestion was pretty much the opposite of what
you refer to. The idea is to be able to play drm protected audio (that
you have paid for) in linux *without* contacting Microsoft the whole
time and feeding the beast. The problem is Windows media player/Windows
and it's privacy breaches. If we could do the the whole thing in linux
we could have control over what gets sent to whom and when. Sadly, we
can't do it technically but if we could it would be good I think.
Does anyone know where one get the specs for this encrypted .wma codec
if they are available?
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