Re: MP3 decoder packaged with XMMS
On Sat, Jul 16, 2005 at 12:54:04AM -0700, Michael K. Edwards wrote:
> I wrote:
> > Presumably you are also aware of patents 5,341,457 and 5,627,938,
> > which Lucent has been seeking to enforce against Dolby AC-3. As your
> > encoder appears to use Ehmer's tone masking techniques, which are also
> > cited in the AC-3 standard definition, ...
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.
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
> I am of course aware that Ehmer's techniques were published in 1959;
> but the combination in the claims of the '457 patent is presumptively
> a valid invention, and I don't grok either it or psy.c well enough to
> be able to tell whether they coincide. It seems particularly timely
> to raise the issue since Dolby is quite capable of settling out of
> court now that they have gotten what they wanted (declarative relief
> WRT AC-3 and Lucent's patents), and if Xiph.org or someone else wants
> to intervene to demand resolution of the question of the Lucent
> patents' validity then the time is presumably now.
Was this declarative relief preemptory or the result of litigation.
If it's preemtive... how the H*** did they manage to do that?