The latest DRM for HD DVD and BD - AACS Audio Watermarking

[Ruined]

http://www.verance.com/news/releases/07-02-07.html
http://www.verance.com/vcms/howitworks.html

What this technology does is essentially embed a signal in the audio stream that it is mandatory for the player to look for. If that signal is found and the title has standard AACS protections broken, the player will refuse to play the disc. So, even if you have decrypted the HD DVD/BD with one of the programs available, you will be unable to playback the stream because of the watermark.

Now, this particular DRM is not as "evil" as BD+, however it still will affect playback. First of all, though the company claims the watermark is inaudible, embedding any signal into the waveform essentially makes mathematical lossless encoding impossible, as the added watermark will change the waveform from the master permanently. The stronger the watermark, the more the resulting stream will differ from the master and likely the more audible noise as well. Most likely if companies really go overboard with the watermark it will introduce noise into the audio stream like any other watermark.

The main problem with watermarks is that they are defeatable, but in this case you'd likely have to degrade the audio quality significantly to defeat it. On the plus side, unlike BD+ this technology is not a security risk, however AACS watermarking does affect the quality of the audio stream and it does restrict our rights as consumers.

So, in summary, this seems like a good technology to prevent copying but IMO it is not quite as evil as some of the other schemes as it does not give the studios carte blanche. What do you all think?

[chlngr1970]

Is it possible to produce this "audible" signal at a frequency that is inaudible by human hearing?

Just curious...

j

[ganthc]

I'm wondering that if bd+ is instituted whether the watermark is a redundancy that can potentially negatively affect the quality of the audio? If bd+ works, then would the watermark be necessary? So hd-dvd can deal with the watermark problems, while bd can just rely on bd+ for content protection, and not deal with the possible reduction in quality.

[Ruined]

Originally Posted by chlngr1970

Is it possible to produce this "audible" signal at a frequency that is inaudible by human hearing?

Just curious...

j

Well, the problem with that is that if they put the watermark only in the inaudible range such as 20khz-24khz, then a pirate could simply use a low pass filter to dump the watermark and audio would be unaffected. So they need to put the watermark in the audible range to make removal difficult and quality-damaging if attempted.

[Ruined]

Originally Posted by ganthc

I'm wondering that if bd+ is instituted whether the watermark is a redundancy that can potentially negatively affect the quality of the audio? If bd+ works, then would the watermark be necessary? So hd-dvd can deal with the watermark problems, while bd can just rely on bd+ for content protection, and not deal with the possible reduction in quality.

The watermark is a mandatory part of the final AACS specs, meaning both HD DVD and Blu-Ray manufacturers must incorporate it into their players. It is up to the studios what they want to use. DRM savvy studios like Sony and Fox will probably use everything in the book to protect their content.

[ganthc]

Originally Posted by Ruined

The watermark is a mandatory part of the final AACS specs, meaning both HD DVD and Blu-Ray manufacturers must incorporate it into their players. It is up to the studios what they want to use. DRM savvy studios like Sony and Fox will probably use everything in the book to protect their content.

Yes, but by your description up top, they could put the watermark in the inaudible range to meet the mandatory standard, while relying on bd+ to secure the content.

[Ruined]

Originally Posted by ganthc

Yes, but by your description up top, they could put the watermark in the inaudible range to meet the mandatory standard, while relying on bd+ to secure the content.

As I stated above, if they put the watermark in the inaudble range (20khz+) there is no point to using a watermark because you could just use a 20khz lowpass filter to remove it. A watermark is only effective when it is in the visible (for video/photo) or audible range (for audio) because there will be no effective way to remove it without lowering the quality of the stream.

So, this DRM effectively ends any "mathematical lossless" qualities to audio that were in place prior to its use. Now we will have "noise" introduced in the audible range that will likely be perceptually inaudible but obviously still there mathematically.

[ganthc]

Originally Posted by Ruined

As I stated above, if they put the watermark in the inaudble range (20khz+) there is no point to using a watermark because you could just use a 20khz lowpass filter to remove it. A watermark is only effective when it is in the visible (for video/photo) or audible range (for audio) because there will be no effective way to remove it without lowering the quality of the stream.

So, this DRM effectively ends any "mathematical lossless" qualities to audio that were in place prior to its use. Now we will have "noise" introduced in the audible range that will likely be perceptually inaudible but obviously still there mathematically.

So you completely ignored what I said, and just repeated what you said before. I asked, if bd+ is effective, and watermarks do affect audio quality, the watermarks could be placed in the inaudible range just to meet with the mandatory requirement for AACS, while relying on bd+ to protect the content.

[Ruined]

Originally Posted by ganthc

So you completely ignored what I said, and just repeated what you said before. I asked, if bd+ is effective, and watermarks do affect audio quality, the watermarks could be placed in the inaudible range just to meet with the mandatory requirement for AACS, while relying on bd+ to protect the content.

Ah I didn't understand your question, but the answer is really the same.

Its not mandatory for studios to actually use the watermarking DRM, its just mandatory for players to have the watermarking protection/DRM specs built into them in case a studio does want to use them.

So, in your example a studio would simply not use the watermark at all if they just wanted to use BD+. When audio watermarking is used, the only effective place to use it is in the audible frequency range (frequencies lower than 19-20khz) so your scenario is very unlikely.

However, my guess is that studios that would employ BD+ would most likely employ audio watermarking, too - since the watermark is perceptually inaudible according to the company that makes it there should be no way to tell that a disc is watermarked without someone buying it, decrypting it, burning it, and then attempting to play it. It would say "24bit/48khz Lossless TrueHD (or PCM) 5.1 Surround Sound" and you would really have no idea that the watermark was stuck in there until a "hacker" exposed it. That being the case, there would be little incentive for a DRM-hungry studio to NOT use the audio watermarking as it will essentially be hidden for some time and there will be no immediate way for the consumer to know that the audio track is marked.

[ganthc]

Originally Posted by Ruined

Ah I didn't understand your question, but the answer is really the same.

Its not mandatory for studios to actually use the watermarking DRM, its just mandatory for players to have the watermarking protection/DRM specs built into them in case a studio does want to use them.

So, in your example a studio would simply not use the watermark at all if they just wanted to use BD+. When audio watermarking is used, the only effective place to use it is in the audible frequency range (frequencies lower than 19-20khz) so your scenario is very unlikely.

However, my guess is that studios that would employ BD+ would most likely employ audio watermarking, too - since the watermark is perceptually inaudible according to the company that makes it there should be no way to tell that a disc is watermarked without someone buying it, decrypting it, burning it, and then attempting to play it. It would say "24bit/48khz Lossless TrueHD (or PCM) 5.1 Surround Sound" and you would really have no idea that the watermark was stuck in there until a "hacker" exposed it. That being the case, there would be little incentive for a DRM-hungry studio to NOT use the audio watermarking as it will essentially be hidden for some time and there will be no immediate way for the consumer to know that the audio track is marked.

Ah fair enough. I agree that Sony and Fox at least will keep the watermark in their audio tracks.