[MPlayer-users] .wma audio fails to play - an example

Arpi arpi at thot.banki.hu
Sun Jul 27 21:45:24 CEST 2003


> 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.

Lol. It means that your soundcard has to be able to decrypt the data?
I doubt an old (or even a current cheaper one, without a decent DSP)
is able to do that, rendering eth whole idea unsaleable.

Anyway you could use digital out of soundcard, loopback to another soundcard
with digital input and record it...

A'rpi / Astral & ESP-team

Developer of MPlayer G2, the Movie Framework for all - http://www.MPlayerHQ.hu

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