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From: Abramo Bagnara <abramo@alsa-project.org>
To: Paul Davis <pbd@op.net>
Cc: alsa-devel@alsa-project.org, Jaroslav Kysela <perex@perex.cz>
Subject: Re: another control API issue
Date: Wed, 08 May 2002 15:00:30 +0200	[thread overview]
Message-ID: <3CD9216E.BB354D6A@alsa-project.org> (raw)
In-Reply-To: 200205081228.g48CSHD24864@post2.fast.net

Paul Davis wrote:
> 
> >Just for curiosity, what they store that cannot be represented in 32
> >bits?!?
> 
> RMS meters. It seems that the 64 bit-ness comes from it being some
> kind of fixed point representation - the value that you read from the
> registers need scaling (in user space, presumably) by a floating point
> transformation to actually become true RMS values. so its not so much
> they they need 64 bits of precision, more that the hardware needs to
> do the math with this type of data format. keep in mind the
> computation is all being done on a Xilinx FPGA, not a DSP chip, so the
> arithmetic options are (at this time) a bit limited.

I expected something similar. Don't you think that to have a FLOAT type
is a better choice (more card independent, more accessible, more
representative, etc.).

-- 
Abramo Bagnara                       mailto:abramo@alsa-project.org

Opera Unica                          Phone: +39.546.656023
Via Emilia Interna, 140
48014 Castel Bolognese (RA) - Italy

ALSA project               http://www.alsa-project.org
It sounds good!

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  reply	other threads:[~2002-05-08 13:00 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-05-08  0:08 another control API issue Paul Davis
2002-05-08  7:57 ` Jaroslav Kysela
2002-05-08  8:04 ` Abramo Bagnara
2002-05-08 12:29   ` Paul Davis
2002-05-08 13:00     ` Abramo Bagnara [this message]
2002-05-08 13:07       ` Paul Davis
2002-05-08 14:00         ` Abramo Bagnara
2002-05-08 14:06           ` Paul Davis
     [not found] <200205081405.QAA07519@alsa.alsa-project.org>
2002-05-08 14:13 ` Abramo Bagnara

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