Author Topic: can digital filter coefficients be copyright  (Read 2572 times)

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Offline f5r5e5d

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can digital filter coefficients be copyright
« on: October 07, 2015, 11:20:10 pm »
I see a audio DAC with the claim "The filter is absolutely proprietary"

which seems to be a bit unclear - are digital filter coefficients themselves considered computer programs - or are they Mathematical results - the former is copyrightable - Math absolutely not
 

Offline rfeecs

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Re: can digital filter coefficients be copyright
« Reply #1 on: October 07, 2015, 11:29:25 pm »
Maybe their filter is like the recipe for Coca-Cola.  It's absolutely proprietary.  But not copyrighted.
 

Offline helius

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Re: can digital filter coefficients be copyright
« Reply #2 on: October 07, 2015, 11:40:20 pm »
"Proprietary" could mean they are considered a valuable trade secret. This doesn't provide any of the protections of copyright, but could be a liability for anyone who discloses them without permission.
Fonts are the same way: the shape of a letter is a mathematical curve, and is furthermore a utilitarian invention since it is a tool used to convey information. But by presenting them as "font programs" that have "creative components" (like text comments), the vendors attach an aura of copyright to them.
 

Offline f5r5e5d

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Re: can digital filter coefficients be copyright
« Reply #3 on: October 08, 2015, 12:00:38 am »
in principle the coefficients are discoverable without popping the lid - structured digital test signal input cross correlated with measured signal output - some information loss from the DAC/ADC step with noise and nonlinearities but you could average lots of trials...

bus sniffing would be more reliable - could be at the DAC input if there was a practical inability or legal need to avoid disassembly of the program

afaik trade secrets discoverable this way simply aren't secret, legally protectable if you have no contractual obligation to the trade secret holder
 

Offline marshallh

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Re: can digital filter coefficients be copyright
« Reply #4 on: October 08, 2015, 09:51:38 pm »
Put step impulse in, log output, poof there's your coefficients.
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Offline photon

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Re: can digital filter coefficients be copyright
« Reply #5 on: October 08, 2015, 10:23:39 pm »
Put step impulse in, log output, poof there's your coefficients.
Yes, assuming filter is finite impulse response. No if not.
 

Offline Marco

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Re: can digital filter coefficients be copyright
« Reply #6 on: October 08, 2015, 10:41:28 pm »
Copyright would be useless, patents maybe. Ask people in eastern Texas who don't try to get out of jury duty, they are the experts.
 


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