Random Thoughts – Randocity!

If you’re into playing back movies on your PS3, you might have run into an annoying problem where your movie plays for about 20 minutes, then the audio suddenly drops out entirely with a warning message on the screen. This is Cinavia. Let’s explore.

What is Cinavia and how does it work?

Cinavia is an audio watermarking technology created by the company Verance where an audio subcode is embedded within digital audio soundtracks at humanly imperceptible levels, but at a level where a DSP or other included hardware chip can read and decode its presence. Don’t be fooled by the ad with smiling children on the Verance site, this has nothing to do with helping make audio better for the consumer. No, it is solely created for industry media protection.

This Cinavia watermark audio subcode seems to be embedded at a phase and frequency that can be easily isolated and extracted from an audio soundtrack, then processed and determined if it’s valid for the movie title being played back. Likely, it’s also an analog audio-based digital carrier subcode (like a modem tone) that contains data about the title being played.

How is Cinavia used in the film industry?

There are two types of known uses of Cinavia watermarking. The first use is to protect theatrical releases from being pirated. Because the audio watermarking is audible, but imperceptible, it will be picked up by microphones (strictly because of the Hz range where the subcode is embedded). Keep in mind that just because the subcode cannot be heard by human ears, it doesn’t mean it can’t be heard and decoded by a specialty hardware chip. So, if a theatrical release is CAMed (i.e. recorded from the screen), the Cinavia watermarking will also be recorded in the audio. After all, what is a movie without audio?

The second use is to protect Blu-ray copies of films from being pirated. For the same reason as theatrical releases, Blu-ray films are also embedded with a subcode. But, that subcode is different from theatrical films. For this reason, films destined for theatrical releases will never play in a consumer Blu-ray player ever (including players such as the PS3, PS4 or Xbox One). Commercial Blu-ray disks play because the audio track uses AACS with a key likely embedded within the subcode watermark. If the AACS key matches the value from the watermark, the check passes and the audio continues to play.

I have also read there is a third use emerging… to protect DVD releases. But, I have yet to confirm any DVDs currently using this technology. If you have run into any such releases, please leave a comment.

How would I be affected by this?

All consumer Blu-ray players manufactured after 2012-2013 are required to support Cinavia. If the Cinavia subcode is present, the player will blank the audio track if the AACS key is mismatched. This means hardware Blu-ray players from pretty much any manufacturer will be affected by Cinavia protection if the title supports it. CAM copies of theatrical releases will never play because the audio subcode is entirely different for theatrical films and the Blu-ray player will recognize that theatrical subcode and stop audio playback.

Not all movie titles use Cinavia to protect their content. Not all players support the Cinavia protections from all media types. For example, some Blu-ray players can play media from a variety of sources beside BD disks (e.g., USB drives, Network servers, etc). These alternative sources are not always under Cinavia protection even if the specific movie has an embedded subcode.

Since Sony is the biggest proponent and user of this technology, all Sony players, including the PS3 and PS4 along with their standalone Blu-ray players will not play back Cinavia protected material if it doesn’t continue to pass the subcode tests. For example, if you rip a Blu-ray disk protected by Cinavia and then burn it to a BD-rom disk, the movie will stop playing audio at around the 20 minute mark and display a warning. If you attempt to stop and start the movie, it will play audio again for a few seconds and then stop playing with a warning.

How can you remove Cinavia protection?

In short, it’s not as easy as that may sound. Once the Cinavia protection is detected on the media, the hardware activates and continues to look for the information it needs to make sure the content is ‘legitimate’.

With that said, there are ways of getting around this on certain devices. As I explained, some players don’t check for Cinavia for certain types of media (i.e., USB or Network streaming). Sony, however, does check for all media types. The PS3, though, doesn’t seem to check for Cinavia if the playback is through the optical output port (i.e., when playing back through an optical receiver). That would make sense, though, as it would be left up to the receiver to blank the audio based on Cinavia. Since most receivers probably don’t support Cinavia, there should be no issue with playback.

Other technical methods include garbling the audio somewhat or using variable speed on the audio. Neither of these two methods are really acceptable to the ears when watching a movie. We all want our movies to both look and sound correct.

How can I avoid this problem?

You can easily avoid this issue by using a a player that doesn’t support Cinavia protection. For example, Windows Media Player, VLC, etc. Most PC media players do not support Cinavia. Though, if you get a PC from Sony, expect the media player on any Sony product to support Cinavia (yes, even Windows Media Player might as Sony may have loaded a system-wide Cinavia plugin). If you buy a PC from any manufacturer other than Sony, you likely won’t be affected by Cinavia.

This problem almost solely exists on Blu-ray standalone players. So, if you avoid playing movies on such consumer hardware players, you can usually avoid the Cinavia issue entirely. Though, there are some commercial PC media players that do support Cinavia.

A possible real solution?

Another method which I have not seen explored, I have decided to propose here. With a film protected by Cinavia, the Cinavia subcode should exist both within silence as well as noisy portions likely at the same volume. First, extract a length of silence (that contains Cinavia subcode). Now, garble, stretch, warp and generally distort this subcode so that it cannot be recognized by a Cinavia decoder. Then duplicate the garbled ‘silence’ subcode to fill the length of the entire film. Extract the film’s audio soundtrack, mix in the new garbled full length subcode throughout the entire film. Note that remixing 7.1 or 5.1 track is a bit tricky, but it can be done. I would suggest inserting it on the subwoofer track or the center track, though it may be present on all of the tracks by design. After the audio track is remixed and remuxed into a resulting MP4 (or other format), the new garbled subcode should hopefully interfere just enough with the existing already-embedded subcode to prevent the Cinavia protection from getting a lock on the film’s original subcode.

The outcome of the garbled subcode could cause one of two things to happen. 1) The Cinavia detection is rendered useless and the Cinavia hardware ignores the subcode entirely or 2) The Cinavia detection realizes such tampering and shuts down the audio track immediately. While erroring on the side of fail is really a bad move in an industry already fraught with bad press around failed past media protection schemes, I would more likely suspect scenario number 1. But, it’s probably worth a test. No, I have not yet had time to test my theory.

While this doesn’t exactly remove Cinavia, it should hopefully render it useless. But, it won’t recover the lost audio portions being used by the Cinavia subcode.

How would I go about doing this?

I wouldn’t attempt doing the above suggestion manually on films as it takes a fair amount of time demuxing audio, creating the garbled audio subcode, remixing the new track and remuxing it into the video. But an application capable of ripping could easily handle this task during the rip and conversion process if provided with a length of garbled subcode.

[Updated: 2018-01-06]

Apparently, DVDFab seems to have a way to rip and disable Cinavia protections according to their literature. They have released the DVDFab DVD and Blu-ray Cinavia Removal tool. If you’re still having difficulties with Cinavia while watching your movies, it might be worth checking out this tool. Note, I have not personally used this tool, so I can’t vouch for its effectiveness. I am also not being sponsored by DVDFab in this article. I’m only pointing out this tool because I recently found it and because it seems to have a high rating. On the other hand, I do see some complaints that it doesn’t always recognize and remove Cinavia on some movies. So, caveat emptor. Even though it’s not an inexpensive product, it is on sale at the time of this update for whatever that’s worth.

It seems that someone finally may have implemented my idea above. Good on them if they did… it only took around 4 years.