Here you will find some insight about DRM conversion techniques.

DRM protection was primarily designed to limit usage of purchased media to certain PC or portable device. But what if you have a device which doesn't support DRM media? Or what if you want to listen to your music in your MP3 car audio. Imagine that you bought or rented some music, but due to DRM limitations you are bound to only one PC that is authorised to play those protected files. At this point there must be a way to bypass restrictions. And this way exists.

Theoretically all you can hear or see can be recorded. For example you can connect your old tape-recorder to your PC, then play your music files and capture them back to PC after that. The way is too slow, complicated and sound quality will degradate noticeably.

What actually DRM converters give you is the way to re-record your music files automatically and almost losslessly. It means that data flow is digital (except for analog audio loop), but some digital transitions usually take place.

Currently there are several conversion techniques implemented by different DRM converter products:

1. Virtual Audio Device - is the most universal and almost lossless technique. DRM converter will just play your DRM music through virtual speakers while capturing and recording produced digital audio output.

Advantages:

- you may convert all that you can play.

• - you may convert several files simultaneousely (each through its own virtual sound device).
• - may utilize as much logical CPUs as you have for faster conversions.
• - audio data usually comes through virtual device without sampling frequency, channel count and sample bit-depth transformations.

2. Analog Audio Loop - is the predecessor of Virtual Audio Device technique. For conversion using this technique you must have a special audio loop cable connecting your line-out and line-in jacks.

Advantages: no

Disadvantages:

• - noticeable quality loss during DAC (digital-to-analog) and subsequent ADC (analog to digital) conversion.
• - only one conversion at a time is possible.
• - complex steps of conversion setup.
• - usually requires special cord to connect line-in and line-out of audiocard.

3. Virtual CD-RW device - exploits possibility for some DRM files to be burned on a regular audio CD. Virtual CD-RW device captures the data and sends it to a converter which saves it to reqular audio files.

Advantages:

• - might be more reliable on old and slow computers having slow CPUs that make impossible real-time audio encoding.

Disadvatages:

• - requires the user to do a lot of manual steps to get desired files burned onto virtual CD-RW.
• - DRM files must have a license permission to be burned. This is the noticeable limitation, because usually files downloaded from a subscription service do not have burning rights until they are purchased.
• - Audio data is always converted to 44Khz 16bit stereo (according to Red Book audio CD standard). This is a little bit inconvenient if you have your protected files with 96Khz sampling frequency with 24-bit depth or if you convert audiobooks which are usually of low sampling frequency and monaural.