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What about watermarks?

Discussion in 'High resolution audio' started by listen, Sep 11, 2003.

  1. listen

    listen Member

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    Every DVD-A release is watermarked. If I remember correctly, one of the 'features' of the watermarking technology is that it must survive mp3 compression, and other bad things too. I'm sure the technology has been cleverly engineered, but at the same time, mp3 codecs are very highly tuned, the aim being to remove everything that is inaudible. If the watermark manages to remain intact throughout a highly destructive 128kbps mp3 encode, then clearly the encoder is not doing its job, and it may be tuned to the point where the watermark disappears. Unless, of course, the watermark is colouring the sound in an audible way, which would be a very sad thing to happen to a format that is otherwise so much better than a CD.

    I think SACD uses a similar technology, but I'm not sure.
     
  2. tigre

    tigre Moderator Staff Member

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    Why even bother? If one thinks his ears need DVD-A he hardly will use mp3 because he'll probably think it's crap.

    Think about this example for watermarking:

    Split a song to parts of e.g. 1 second. Now take every part and either let it as it is or apply a fadein-fadeout to it with volume difference something like 0.1dB. Now join the parts. There won't be any audible difference, but when you've got the original and compare both, you'll find some barcode-like pattern that survives many manipulations (lossy compression, equalizing etc.). Of course if you know how it works, you can crack it, but how exactly a certain watermarking system works is secret in most cases.

    So properly designed watermarking won't change the sound noticably and is resistant against mp3 encoding.

    BTW: Does anybody know if DVD-V contains watermarking for audio of audio is stored as (high resolution) PCM?
    Some examples: http://www.chesky.com/catalog/body_catalog.cfm?category=2_X_X_X_X_X_[small]AFTERDAWN FORUM RULES: http://forums.afterdawn.com/thread_view.cfm/2487[/small]
     
    Last edited: Sep 12, 2003
  3. listen

    listen Member

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    Never mind whether people use mp3 or not, the watermark is still going to be on the DVD-A.

    Yes and that's the problem. How can you say that there should be no noticeable effect without knowing how the system works? How can anyone say there is no audible difference when there is nothing to compare to?

    I would very much like to be wrong, but I insist on being proved wrong rather than assumed wrong.
     
  4. listen

    listen Member

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    I'm pretty sure that watermarking isn't part of the DVD-V spec. So I think they would have to show that evil little 'cp' logo if they wanted to introduce it now.
     
  5. listen

    listen Member

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    Has nobody got anything to say??

    I want to start buying DVD-As, but they are not very tempting if I don't know whether they're marred or not. I guess any difference caused by watermarks would be very subtle (if there is a difference) and this all sounds a bit paranoid, but that's really what supplanting CDs is all about... subtleties and paranoia.
     
  6. wilkes

    wilkes Regular member

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  7. listen

    listen Member

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    Awesome... it's good that somebody is interested.

    I'm wondering at the moment if it's even possible to ever really know if it's transparent or not. The details of the watermarking method will probably never be disclosed, because then the system would be cracked very fast. And of course they will say it is transparent, because it's a fundamental part of the format. It would just be good to know for sure. But do we ever, really, know? :D
     
  8. wilkes

    wilkes Regular member

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    Found another very good link for you on all this.
    Go to http://webbd.nls.net:8080/~mastering/login
    and check out the top item - it's all about various different watermarking technologies, and their drawbacks/advantages.
    You will have to register with the site, but it really is worth the trouble as just about everyone who counts in Pro Audio goes there, from Bob Clearmountain, Glenn Meadows, Bob Katz, etc etc.
    You'll be in good company.
     
  9. listen

    listen Member

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    Nice link, thanks for that.
    There doesn't seem to be much discussion about watermarks any time in the last few years, so maybe I will sign up there and start hassling them about it... :p
     
  10. wilkes

    wilkes Regular member

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    Oddly enough, I got this in my email a day or so ago.

    neilwilkes@opusproductions.com writes:
    >What is the copy protection on DVD-Audio?

    Content Protection for Pre-recorded Media (CPPM) from the 4C entity
    (www.4centity.com). It is implemented during glass mastering but there
    may be some authoring issues.


    >I author DVDA on DVD-R and DLT, and a customer insists that Watermarking
    >is mandatory. Is this true, and if so who does it and will it interfere
    >with my audio?

    Watermarking is not mandatory.

    >Please can you send full details on what I need to do and Know as a DVDA
    Author, please?

    >I should contact Sonic Solutions at www.sonic.com.

    >Also, if making a "universal" disc, with ATS & VTS, what is the copy protection status there?

    CSS can be used on the DVD-Video part
    See http://www.disctronics.co.uk/downloads/tech_docs/dvdaudio.pdf for a
    paper on DVD-Audio.

    There you have it, from the replicators.
     
  11. wilkes

    wilkes Regular member

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    Sonic Solutions are only interested in trying to sell you their $18000 dollar Easy DVD Creator software!
    BTW - I hear that Minnetonka are updating discWelder series. Steel 2 is already out, and Chrome 2 is due to be announced soon. I know what the upgrades are, but cannot say. Suffice it to comment that this will be a MAJOR development in affordable DVDA.
     

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