Blocked BD copy playback (Cinavia)

[Jong]

I think it will be mostly Cinavia that is heard and I agree that listening is not going to be scientifically helpful, but would be interesting

If a lossless HD track with Cinavia is really worse than the lossy DVD track, then they really have got problems!

 

[Jong]

No you do not need to repeat the equations and no they do not clear anything up. You are simply stating as fact that C is greater than N with no supporting evidence. They would be truly mad to use Cinavia on an HD track if it's effect was to distort the original audio more than the compression artefacts introduced by DD/AC3. Then the audio quality of the HD track on the bluray would be worse than the DVD track. I would expect the artifacts in AC3 to swamp the Cinavia signal. Of course it is remotely possible they are mad, but it is unlikely.

 

[Jong]

No offence, but you do seem very sure of the cleverness of a very simple idea. It is trivially obvious that IF you have an absolutely identical master used for DVD and Blu-ray it is possible to reverse engineer the DVD track from The Blu-ray and your "N-C" track.

However, I think you will find such identical masters from disc to disc to be rarer than you might expect and it seems highly unlikely to me that Cinavia would have more of an audible impact than AC3 compression, which is the logic of your assertion that C is greater than N. If it did, it would surely stop them claiming the bluray audio was HD at all.

 

[Jong]

OK, I think I get your confusion! My point was never that the relative size of C and N affected the ability to remove C (and replace with N).

My points were:

- if C was audibly greater than N it would make blu-ray audio inferior to DVD. I do not think even movie studios would be that stupid
- even if C and N are roughly equal, we know for a fact that N is audible - it is principally the sound of compression artefacts in lossy AC3 - so it is impossible to judge whether C affects audio quality by listening to the N-C track.

Of course, I do appreciate the other advantage of replacing C with N - namely avoiding Cinavia detection in a player. When possible, it certainly would be a benefit to those affected.

 

[Jong]

It's true that in many home environments HD audio is of no benefit over DD. But it is also true that in a good environment artefacts from AC3 compression are audible and lossless compression on bluray is of value. This is not an arcane Audiophile issue, like some.

It's hard to see how you would cleanly remove DD artefacts (ie. without adding your own) without access to the original master, or a losslessly compressed HD track without Cinavia. If it were possible all the top AVRs would be doing it already.

 

[Jong]

I deleted the comment about improving the N factor

But anyway, this method of deleting the watermark does theoretically work.
I think you're still too worried about noise. It's a common mistake

What's with your patronising attitude. if you want to be part of an online community I would drop it.

People pay good money for blu-ray over DVD in part for HD audio. It is fair to point out that this is of little to no value in many home environments but claiming compression artifacts are of no concern rather begs the question of why the studios are taking up many times the space of a DD soundtrack on blu-ray discs for DTS-MA and TrueHD lossless tracks.

Seeing benefit in a true, mathematically, lossless, audio track over lossy AC3 compression is not a "mistake". As an engineer you should appreciate that.

 

[sierra117]

BTW, I am not suggesting that this research is a long term solution for deleting Cinavia, but it is necessary investigation into understanding how Cinavia works in the real world. The first step is to figure out how to delete it once.

You can't see the low frequency modulation difference in the graphs. The BD audio definitely has a larger higher average amplitude and wider bandwidth. The only way I noticed it was by listening in the headphones.

My next steps are to normalize the relative amplitudes. Then apply a constant factor to the BD audio to equalize it with the DVD audio's amplitude. Then invert the BD audio and sum it with the DVD audio to derive the Cinavia signal itself.

I can't think of any theoretical reason why this low frequency amplitude difference would occur with different mastering techniques, but the reason for it is trivial once you know it's there, you can compensate for it.

i find what you're doing to be pretty interesting, i myself am into audio but don't quite consider myself a full-audiophile. i would do my own tests as well, except i don't have much time to analyze audio from dvd/bd.

if slysoft is listening to this thread, there's a good possibility you can help the devs, be it advice or getting in on this project ....

whether the algorithm is reverse engineered this way or discovered via cracked cinavia-check modules on board devices like the PS3, i have no doubt i'll be able to strip the stuff out of my movies in the future .... if not, then i will have to have a dedicated PC for home theater as i wouldn't want to rely on hardware players that can introduce cinavia in firmware. when spending some decent cash for a device like an oppo bdp-93, it would be gravely disappointing to find out they issue a cinavia firmware update and have no way of playing new movies without the latest keys (read: latest firmware).

 

[fast eddie]

if not, then i will have to have a dedicated PC for home theater as i wouldn't want to rely on hardware players that can introduce cinavia in firmware. when spending some decent cash for a device like an oppo bdp-93, it would be gravely disappointing to find out they issue a cinavia firmware update and have no way of playing new movies without the latest keys (read: latest firmware).

Yes, Zero I agree with you, but Cinavia is in its infant stage, unless some group or dedicated company kills it soon, Cinavia ( better known as cancer) has the potential of getting into software playing too, especially if it is sucessfully in killing hardware players. I believe Cinavia is widely underestimated on the killing potential it can do now and in the future.

 

[SamuriHL]

Yes, Zero I agree with you, but Cinavia is in its infant stage, unless some group or dedicated company kills it soon, Cinavia ( better known as cancer) has the potential of getting into software playing too, especially if it is sucessfully in killing hardware players. I believe Cinavia is widely underestimated on the killing potential it can do now and in the future.

And I believe it's vastly overstated as to what it can and can't do. It will get added to commercial software players. It will never be added to freeware players. It won't get added to drivers. It won't get added to the os. It's not magical. It simply is a mechanism to tell a player to check if the media it's playing is from a trusted source. That's it.

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[James]

i'm pretty sure that the same watermark is on both the DVD and BD versions I'm using thus making simple 1:1 analysis completely useless for this title.

Is there an AACS directory on the DVD? If not, it can't have Cinavia, or it won't play on a PS3.

 

[PrincipalityFusion]

Is there an AACS directory on the DVD? If not, it can't have Cinavia, or it won't play on a PS3.

but..but...he did SPECTRAL ANALYSIS!!

 

[SamuriHL]

No AACS folder, no Cinavia. Period.

(On a DVD, of course)

 

[Ch3vr0n]

afaik it will trigger, as it's the audio that carries the cinavia signal. Not the video. You could point your camcorder at the wall and record with a cinavia movie playing in the background. When you'll playback the camcorder video it'll trigger cinavia

 

[SamuriHL]

On another note, has anyone tried just streaming Cinavia infected audio (no video) to a PS3 to see if that will trigger Cinavia?
TIA

You really should go back and read the history of what's been done to test cinavia. I spent many days running all kinds of tests. Even a stereo audio only track will trigger it.

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[SamuriHL]

No disrespect, but I'm not convinced of that yet. Did you read my rational for why it could have the watermark?

I agree that "No AACS folder means no Cinavia", but there is no reason why it can't have the watermark. Cinavia is more than just the watermark and there could be an exception in the firmware for structurally protected DVDs. My backed up DVD also ended up with structural protections.

It's also possible that the DVD has a watermark but is obfuscated enough to make comparison identification more difficult but does not trigger the Cinavia errors.

Did I read it? Yes. Did I buy it? No. Prove to me there's cinavia on a structurally protected disc with no aacs folder. Not speculation...proof. It'll be very easy to prove...take a disc you think has cinavia and structural protection and convert it to another format...say mp4. Play it on a ps3.

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[SamuriHL]

That's not proof. That's speculation based on some supposed observed spike. Iow, it's nothing more than forcing an interpretation of some analysis because that is the result you desire. You have not proven anything with your analysis yet.

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[SamuriHL]

What i mean is that you haven't shown that what you've isolated is in fact cinavia. You *think* you *might* have isolated it. But that's not proof of anything.

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[Ch3vr0n]

Well, if you know how you could try to eliminate that "spike signal" you saw from the original source into a new audio file and. Demux the original audio from the video and remux your new audio into the video and then test it. If it still triggers cinavia then what you saw was a fluke and unrelated to the cinavia signal. However if it DOESNT trigger, then you may be on to something (or "solved" the damn thing) but i don't think it will be that easy or someone would have done it ages ago.

 

[SamuriHL]

You are right about that. I haven't proven this is Cinavia. All I've proven is that both have odd narrow band, inaudible spikes that appear on both BD and DVD's at the exact same places. I need testers for the real proof.

That was my point. It wasn't to invalidate your theory. Merely that nothing has been proven.

15709 is the most prominent which is very close to 15750 which is the NTSC horizontal synch frequency. But there is no reason for this to appear in the audio, especially the BD version.

My problem with your theory is that there would be *NO* benefit to putting the Cinavia signal on a DVD in such a way that masks its effects. It costs them money to add the signal. You theory that somehow it's still on the structurally protected discs yet isn't used or somehow masked to avoid detection doesn't hold a lot of water given the other facts of Cinavia. And what I said about that holds....converting it to a format that removes the structural protection, if your theory is correct, would trip Cinavia. At least according to what you hold as true in your hypothesis. I simply don't buy it. I hold and maintain that if the DVD hath not an AACS folder, then the audio hath not a Cinavia signal...masked or otherwise.

 

[SamuriHL]

I am seeing more than just 15709 spikes. But the only way to find out is to try it. I can accurately notch out these signals without degrading the rest of the audio and need someone to test out the results.

I wouldn't assume that someone else has not already done it, but the only way to find out is to try it.

If this does work, software could be written to do it automatically once the filter parameters are known for a given title.

I would test whatever you want for you as I own a PS3, but, I'm leaving for vacation for a week and won't have time until I get back.