Re: MP3 decoder packaged with XMMS
On Tue, Jul 19, 2005 at 04:05:59PM -0700, Michael K. Edwards wrote:
> That's mighty cool. Can you say anything about the Mercora encoder's
> psycho-acoustic bits
In fact, I can't say much about it (I know all about it but am under
NDA).
> or about how you approach the risk that loading
> a particular codebook into the Vorbis decoder would result in
> something patent-infringing?
The codebooks are huffman trees + a value per leaf: just data. The
code that applies them may infringe, but I doubt very much that raw
data itself can, genomics stupidity notwithstanding.
> Have you tried, just for kicks, mapping
> the AC-3 and/or MP3 techniques onto the Vorbis framework?
Vorbis isn't a framework, it's a codec. A more flexble codec than the
others, but still just a codec.
The techniques used by both mp3 and AC3 are, to put it bluntly,
ancient. Although there was once some 'cargo cult' tendency to try
out what the other encoders did, for the most part the external
techniques turned out to be obsolete or inappropriate. Floor 0 is the
most visible example of taking a cue from outside research without
thinking it through (LSP is a *terrible* idea for wideband encodings).
In general, the 'lock you up tight' patents that the other firms go
for are not ones that strictly affect encoding or the raw bitstream
itself; they attempt to patent sufficient algoritms around the data
that it's impossible to encode/decode the bitstream itself without
infringing. This is another reason I feel relatively secure about
Vorbis; the bitstream looks/works nothing like the competition.
Should, God forbid, Vorbis be accused of using some specific technique
that is not central to handling the bitstream, we could sidestep it
easily. The only worrisome patents are the abusive, overly-broad
ones.
However, the biggest reason I feel secure is that most of the world is
currently using and shipping Vorbis daily. Even Microsoft ships it in
games (where it's not obvious that it's there, but it is nonetheless).
> 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.
Can't happen. The transform domains are not compatable.
> 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.
Mercora is 100% real Vorbis. Aside from a different vedor string I
don't believe they are distinguishable from streams produced by our
reference encoder.
> 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.
The Mercora encoder isn't ours and we have no rights to it, but I will
say it doesn't do anything the reference encoder doesn't. Aside from
that, I'm not sure what your point actually is; the worry that third
parties using Vorbis would be exposing themselves to being forced to
violate NDA?
> I'm just trying to understand
> how deliberately eschewing patents works out in a field littered with
> them.
If I was going to be worried about patents to the level of paranoia
some suggest, I'd have to give up computers and become a blacksmith or
machinist, or something (perhaps a hooligan, that's always appealed,
but I hate soccer and cheap booze). You can't demonstrate
conclusively that a single piece of software, anywhere, does not
infringe any patent. How many patents does GCC 'infringe'? 100?
1000? 10,000? The only answer is: "The courts have not awarded any
infringement claim against the FSF regarding GCC" and that is the
closest practical definition we have of "does not infringe". Vorbis
meets the same definition and, honestly, is really not any more likely
than GCC to see an infringement claim (eg, Microsoft is not 'at war'
with us the way they are with the FSF. Microsoft is about as
aggressive as software companies get, yet for some reason they're not
using the patent card).
The only suggestion, at any time, that there may be an infringement
claim against Vorbis was an off-the-cuff remark from Henri Linde of
Thomson years ago when he was under the impression that 'Vorbis' was
just a tweaked mp3 encoder. He was corrected and retracted his
remarks (but that followup was not widely reported).
> > 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
[...]
At this point a lawyer who knows what actually happened has to weigh
in and let us know; anything else is guessing, hearsay and uninformed
speculation I fear :-( Not that it's ever stopped Debian legal before,
but I'm not personally going to get involved in such a discussion
myself.
Monty
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