Subject: Re: [linux-audio-dev] MMAP + RTC excellent performance , 2.9ms latency during playback !
From: Juhana Sadeharju (kouhia_AT_nic.funet.fi)
Date: ke maalis 08 2000 - 05:44:41 EST
>From: David Olofson <david_AT_gardena.net>
>
>> But what is then US Patent 5,435,863????!!!!
>
>Seriously!? This trick (using an external IRQ source + checking the
>current position of the DMA) has been used for *ages* in PC demos and
Ok, the above patent number was a joke, but I have feeling this is not
as funny then when a future patent does patent something obvious.
Just check those two recent patents I mailed about; both of them seems
to be blocking patent for technology which was used earlier and that
another was even published by well-known dsp person.
Imagine a situation that somebody follows these mailing lists for ideas.
While we are polishing (or not even commenting the thrown ideas) somebody
patents them and we find it out only after two or three years.
Entire audio system is unusable because somebody patented our work
perhaps with a couple of trivial modification and claims right to any
modifications of the scheme. A professional audio coder at known companies
(E-mu would have an attitude for such behaviour as you have seen) would
easily be able of doing that.
What were those patents?
1. instant play; keep first part of audiofile in memory for fast playing;
the patent is about synth but they try to cover as basic feature as
possible making it as blocking patent for jingle players and hard disk
recorders; I found prior art to this;
2. a blocking patent from E-mu for Moorer's reverberation idea; create
impulse responses with a noise signal by filtering it to the desired
shape; this blocked also the use of Phase Vocoder (linear-phase
bandsplitter) as a general filter in this work;
3. mixer inside /dev/audio etc.
4. Lucasfilm, Ptolemy, etc. systems hardwire dsp code to DSP processor;
if this is done in Linux, i.e., assembler is put directly to array
and that is executed, violates it a patent; we most probably don't
even need this stuff it was in my audio engine plans.
Juhana
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