[vorbis-dev] patents and separate entropy coding

Segher Boessenkool segher at wanadoo.nl
Fri Dec 15 19:25:51 PST 2000

Lourens Veen wrote:
> Roger, sorry 'bout that. I am talking about patent claim #US5579430
> which is entitled Digital encoding process and can be found at
> http://www.delphion.com/details?pn=US05579430__

This is the main MPEG patent, right? I'm very pleased about this patent,
as it is too specific :-) It doesn't embody my mp3 encoder.

> It patents "A digital encoding process for transmitting and/or storing
> acoustical sigs and, in particular, music signals, in which scanned

libvorbis doesn't transmit and/or store. Of course, all sensible
applications will :-(

> values of the acoustical signal are transformed by means of a
> transformation or a filter bank into a sequence of second scanned
> values, which reproduce the spectral composition of the acoustical

This is very disputable in case of a MDCT filter bank. The output
of a MDCT filter bank only has _half_ of the spectral information
about that particular block, and so surely can't reproduce it. And
if you're talking not about a block, but about the entire stream: in
that case it's not a transformation, nor a filter bank.

> signal, and the sequence of second scanned values is quantized in
> accordance with the requirements with varying precision and is partially

"With the requirements" doesn't say anything. No requirements were mentioned.
You can't claim anything you don't mention. And it's argueable for any
serious psycho-acoustic encoder, that it quantizes with _equal_ precison,
not varying precision.

> or entirely encoded by an optimum encoder, and in which a corresponding

Neither the mop3 Huffman tables, nor the Vorbis VQ tables implement
optimum encoding.

> decoding and inverse transformation takes place during the
> reproduction."

Prior art (and at least two prior patents, as well).



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