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"Digital Rights Management" (generally abbreviated to DRM) refers to any of several technologies used to control access to and the usage of digital media.
As the name says, DRM is used to manage copyrights of digital media (audio, video, images, etc.), that is, beyond making unauthorized copying more difficult, it allows the accounting of sales, the reinforcements of the usage rights and the control of the distribution of the content.
The protection of the digital file is, many times, confused with DRM systems as a whole, because that this is the focus of the big international disputes and a basic constrain in the restrictions users will face when using the media files.
In context of software development we can focus on the DRM technologies that focus on the file protection schemes.
Today, there are five major DRM "standards":
- FairPlay DRM (Apple),
- WMDRM or Microsoft DRM (Microsoft),
- Open MG DRM (Sony),
- Helix DRM (Realnetworks) and
- OMA DRM (Open Mobile Alliance).
Most of them are focused on music and video but it is possible to use DRM technologies in any kind of media.
The DRM is many times confused with audio format. Although the audio format is also important the types of devices that can be used to hear the music, today this aspect has less appeals between the users since all the formats can have good quality music with minimum file size difference. For example the most popular music store (iTunes) sells files in a lower quality (128kbps) them his competitors (160-192kbps). Since the difference is almost imperceptible for the final user this does not have an impact on sales. I will post a review of the most popular file formats latter.
Some DRMs have restrictions about usable formats, but in all cases, audio format and DRM are separate technologies. Each DRM has its advantages and disadvantages, therefore an ideal or universal format still does not exist and unfortunately none of this technologies are interoperable. Thus if you get a file in one format you can only use it in device that comply to this format.
This is the cause of many controversial disputes and most of the criticism about the use of DRM focus on that problem