We briefly discussed watermarking schemes in the previous section. Cinavia, from Verance, is an audio watermarking scheme which has ended up inconveniencing a number of consumers. In particular, owners of the PS3 have been vocal enough to warrant the appearance of sites dedicated to bypassing the Cinavia triggers on the PS3. What exactly is the Cinavia watermark? How is it embedded in a soundtrack? When does a consumer encounter the watermark? What is the result when the encounter happens? These are some of the questions we will try to answer in this section.

Verance's DVD-A Watermark

Verance is no newcomer to the audio watermarking market. DVD-Audio adopted their technology in the late 90s. Audio watermarks can be robust or fragile, and Verance's DVD-A watermarking scheme as well as Cinavia belong to the former category. Robust watermarks can't be destroyed by digital-to-analog conversion, re-encoding or addition of small amounts of noise to the track.

In fact, Verance was one of the companies involved in the infamous Felten-SDMI Challenge case, where Prof. Edward Felten was threatened with legal action if he wanted to discuss how Verance's DVD-A watermark scheme (along with a host of other audio protection schemes) was deciphered and overcome. Readers interested in the full technical details of Felten's attack in the SDMI challenge can peruse this paper [PDF] presented at the 10th USENIX Security Symposium. In short, Verance's watermarking scheme involved frequency domain modifications, hiding multiple time-varying echoes. Note that the human ear is not sensitive to echoes involving speech and music where the delay is less than 50 ms. In fact, only echoes with a time difference of 100 ms or more become annoying. Verance's scheme involved echoes with delays varying between 0.5 ms and 1.75 ms, rendering them indecipherable to the human ear. By placing these echoes regularly in an audio track, it is possible to detect the watermark in any clipped segment.

Cinavia

In the DVD-A watermark discussed in the previous subsection, Verance could have different echo patterns to indicate different watermarks. Though we don't have the exact details, it is widely believed that Cinavia could be something similar. The fundamental requirement for Cinavia is the presence of a watermark detector in the playback device, i.e, when a Cinavia-infected audio track is being processed, the system must be able to identify the presence of the watermark pattern.

There are at least four different Cinavia watermarks to identify the following situations:

  1. Professional content (say, copies of movies made in a theater) being played on an unlicensed device (say, a Blu-ray player at home)
  2. Professional content being copied using an unlicensed device
  3. Content being played back on an unlicensed device
  4. Content being copied from an unlicensed device

Scenarios (2) and (4) result in copying being stopped. They are comparatively rare (not many users use devices with the watermark detector to copy content). However, scenarios (1) and (3) are more common. Currently, Cinavia audio watermarks are embedded in the audio track(s) of some Blu-ray movies and a number of theatrical releases. The type of watermark in each of these cases is different. While the watermark in the first case may lead to Scenario (1), the second case may lead to Scenario (3).

We set out to observe Cinavia in action. Our first two test cases involved Blu-ray backups of the movies 'The Losers' and 'Battlefield LA' with re-encoded audio and video tracks. The files were played back on a PS3. The third scenario was triggered in both cases. In the former case, the triggering was within a minute, but took more than 20 minutes in the latter case.


Cinavia - Message Code 03 - The Losers by anandshimpi


Cinavia - Message Code 03 - Battlefield LA - 20... by anandshimpi

The current PS3 firmware has the Cinavia watermark detection routines. When the audio track of a file being played back has the Cinavia watermark for Scenario (3), the PS3 usually waits for 20 odd minutes before muting the audio. This scenario is also triggered when lossless backups of Blu-rays are played back. For example, some Blu-ray players have the ability to play back unprotected ISOs (created with AnyDVD HD or DVDFab) or MKVs (created with MakeMKV) which don't even have re-encoded audio / video tracks. These are the most common form of backups used by legitimate Blu-ray consumers. I will touch upon the need for such backups in a later section, but suffice to say that any discs with Cinavia backed up in such a manner (i.e, with the AACS protection removed) will trigger the muting of the audio on Cinavia-enabled Blu-ray players.

Our third test case involved a 5 minute sample clip from a CAM print of the movie 'The Wolfman'. For those not familiar with scene releases, the Wikipedia article explains about the scene and the various qualities in which scene releases are available. A CAM print is made using a camcorder in a theater. The audio can be either recorded using a microphone or explicit line input. In the latter case, the audio track doesn't have a lot of noise. However, our sample clip had very noisy audio, and in all probability, the audio was recorded using a microphone. Within a few seconds of starting playback of the file on a PS3, Scenario (1) was triggered. Playback automatically stopped with the appropriate error message.


Cinavia - Message Code 01 - The Wolfman by anandshimpi

Cinavia and Blu-ray Players

One of the common aspects in the above three videos is the fact that both of them involved the use of a PS3 as the media player. Currently, Cinavia watermark detection is mandated only in the AACS licensing agreement. This means that only players which are licensed by the AACS are required to have this detection routine. An update to the AACS licensing agreement indicated that all players sent to the BDA (Blu-ray Disc Association) for licensing after February 1st, 2012 should have the Cinavia detection routine embedded in the firmware. There is no legal licensing requirement for previously certified players to include Cinavia in firmware updates, but, if the manufacturer wishes to do so, there is nothing to prevent them from doing so.

Note that the licensing requirement doesn't state that all players sold after February 1st, 2012 need to be Cinavia-enabled; it is only those sent for certification after that date. This means that a number of Blu-ray players (older models) will continue to be sold in the market without Cinavia for some months to come. The BDA certification process involves putting each applicant through a rigorous test suite to ensure that all Blu-ray features are properly supported. Since Cinavia is a recently introduced licensing requirement, it is not clear when the Cinavia tests will become part of the BDA certification test suite. We spoke to some industry insiders who stated (on the conditions of anonymity) that it will be at least another 8 - 12 months before the BDA certification test suite starts testing for Cinavia compliance. They also indicated that they fully expect players to be certified in the meanwhile without Cinavia in the firmware.

Cinavia is particularly worrisome for DMAs (Digital Media Adapters) that have also licensed Blu-ray capabilities. Examples of such units include the Popcorn Hour C300 from Syabas, the Dune Smart series from HDI, and players such as the Kaiboer K860i / Asus O!Play BDS-700. Fortunately, all of these units have already obtained BDA certification. However, it will be interesting to see how they tackle the Cinavia issue in the next generation units. DMAs are quite popular because of their ability to play networked media of all types (be it Blu-ray backups in ISO / MKV format or downloaded content). Cinavia throws a spanner in the works for such units. As we demonstrated earlier in this section, audio either gets muted or playback stops completely, depending on the media source.

In the next section, we will present some comments (in the hope that people in the AACS LA and BDA are paying attention), and leave it to them / readers to decide whether Cinavia really helps as an effective DRM measure.

DRM Measures in Blu-rays Analyzing Cinavia
POST A COMMENT

118 Comments

View All Comments

  • archer75 - Wednesday, March 21, 2012 - link

    Clearly your out of touch with how things are done now. MKV's are indeed the way to go for HD and have been for quite a while now. AVI's? Seriously? Reply
  • ~wolverine~ - Wednesday, March 21, 2012 - link

    You have no idea what your talking about. Reply
  • p05esto - Wednesday, March 21, 2012 - link

    Are you serious? MKV is of course the ultimate video format right now, nothing else comes close. You obviously don't know what you're talking about. I rip all my movies to MKV. Only kids posting crappy quality torrents use Divx/Xvid and all the .avi variations.

    Sorry man but H.264 MKV files are THE only way to go.
    Reply
  • SlyNine - Thursday, March 22, 2012 - link

    I'd say for HD stuff MKV is the only way to go. I don't believe you can even put HD audio in AVI. Reply
  • SlyNine - Thursday, March 22, 2012 - link

    Also AVI has limited B-Frame support according to Wiki.

    My guess is you'll be googling what B-Frames are.
    Reply
  • cjb110 - Thursday, March 22, 2012 - link

    I've started seeing a lot more .mp4's about, esp for HD TV stuff. But MKV is by far the leading format that is being used through out the scene.

    AVI's are still popular for the non-hd, or the hd->non-hd conversions.
    Reply
  • khory - Thursday, April 05, 2012 - link

    mp4s are getting popular because a lot of the mobile devices can decode them in hardware. Reply
  • BaronMatrix - Wednesday, March 21, 2012 - link

    I mean sucks. I have to get updates when new movies come out and if my Player doesn't have an update I bought a movie for nothing. At least you can but ones with DVDs in it also.

    And whoever is writing the Java code should be killed. I don't need bells and whistles, I need HD video. AT least you should be able to opt out of special features. I could write that with my eyes closed. And I do C#.

    Someone else mentioned the time it takes to actually play a disc...unacceptable... I still can't get Thor and Green Lantern to play .. at least not all the way through...even more unacceptable... Then when you throw in the horror of the HDMI handshake, it's amazing anyone buys them...Picture and sound is beautiful though...

    IF IT PLAYS...

    I reiterate the SUBJECT.
    Reply
  • Jaybus - Wednesday, March 21, 2012 - link

    Indeed. The problem is not the concept, but the implementation. Very poor quality control. What nobody seems to cover is the fact that BD player manufacturers are forced to operate at really low margins. Then when you consider that at the time they designed a player and set the cost margin, those manufacturers had no idea that the content providers were going to force through a new DRM method practically every time a new movie came out. Those new firmware updates that everyone screams for cost the manufacturer and eat into their already low margins.

    Thus, DRM increases the cost of making BD players. Yet, the BD manufacturers realize that nobody will buy their product if they start raising the price, so they instead cut corners, resulting in poor quality, badly coded firmware with little or no quality control. The push for new DRM methods is making the manufacture of BD players unprofitable, so will in that way eventually kill BD.
    Reply
  • cmdrdredd - Wednesday, March 21, 2012 - link

    Every movie I've ever bought always works on a 1st gen Samsung Blu-Ray player. I have never been asked to update. What you're saying is spewing an internet fallacy back out again like a monkey. Reply

Log in

Don't have an account? Sign up now