Re: MP3 decoder packaged with XMMS
On 7/19/05, Monty <monty@xiph.org> wrote:
> Ehmer's work is cited but we don't actually use Ehmer's data. The
> curves you see in the tonemasking are directly from the ears of yours
> truly measured repeatedly over the space of a month and pessimistic
> mean taken. There's a 4kHz notch there that's actually an unfortunate
> artifact of the measuement.
Interesting. AIUI that doesn't necessarily imply that your "golden
ears" curve wouldn't be ruled to infringe on a nearly
indistinguishable semi-empirical curve if there were such a patent --
but I would think that this aspect of the reference encoder's method
would be ruled unpatentably obvious in light of Ehmer. Which, from a
point of view in which you prefer unpatentable techniques (not least
to reduce the risk of being submarined), is a good thing.
> The irony here is that tone-tone masking is the least useful of the
> techniques Vorbis uses for psychoacoustic measurement. Higher-speed
> vorbis encoders, such as Mercora's, dispense with tone-tone masking
> entirely.
That's mighty cool. Can you say anything about the Mercora encoder's
psycho-acoustic bits, or about how you approach the risk that loading
a particular codebook into the Vorbis decoder would result in
something patent-infringing? Have you tried, just for kicks, mapping
the AC-3 and/or MP3 techniques onto the Vorbis framework?
It would be kind of fun to write a lossless transcoder to Vorbis from
one or more patent-encumbered formats and to see if there are any
discernible patterns in the codebooks. It might also be a prudent
defensive measure so that you can demonstrate what a potentially
infringing Vorbis stream would look like and evaluate to what extent
you can distinguish them from Mercora streams. Could be doubly
prudent if there's anything about the Mercora internals that you
wouldn't want to have to divulge into the public record during a court
proceeding, since presumably in the absence of a patent you have no
way of retaining proprietary rights to that encoder's methods of
operation other than trade secret law.
Note that I have no problem with the Mercora encoder not being open
source, and I'm not trying to use this as some sort of object lesson
in the legitimacy of "software patents" -- though I could see it
shaping up that way in the long run. I'm just trying to understand
how deliberately eschewing patents works out in a field littered with
them.
> Was this declarative relief preemptory or the result of litigation.
> If it's preemtive... how the H*** did they manage to do that?
I am going on the press release at
http://investor.dolby.com/ReleaseDetail.cfm?ReleaseID=161066 ; I
haven't yet gone to the law library for the April 22, 2005 ruling in
the Northern District of California that granted summary judgment of
non-infringement, and I don't even know which judge issued it. I
don't know for certain how Lucent's patents wound up in play; here is
Dolby's spin on it:
<quote>
In May 2001, Dolby filed a lawsuit against Lucent in the United States
District Court seeking a declaration that the '457 and '938 patents are
invalid and that Dolby has not infringed, induced others to infringe, or
contributed to the infringement of any of the claims of these patents.
In August 2002, Lucent filed counterclaims alleging that Dolby has
infringed the two patents at issue directly and by inducing or
contributing to the infringement of those patents by others. Lucent
contended that products manufactured by Dolby licensees incorporating
Dolby(R) AC-3 technology infringe those patents. Lucent sought
injunctive relief and unspecified damages.
</quote>
Cheers,
- Michael
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