X-Authentication-Warning:	delorie.com: mail set sender to geda-user-bounces using -f
X-Recipient:	geda-user AT delorie DOT com
Message-ID:	<5336E080.5080600@buffalo.edu>
Date:	Sat, 29 Mar 2014 11:02:24 -0400
From:	"Stephen R. Besch" <sbesch AT buffalo DOT edu>
User-Agent:	Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.2.0
MIME-Version:	1.0
To:	geda-user AT delorie DOT com
Subject:	Re: [geda-user] Wav to C array ~ 16 bit to 12 bit
References:	<CALSZ9gpoxnz9V-CbisKqmdwQyTtVf6G9nCe2Wt=4p4su-afFBQ AT mail DOT gmail DOT com>
In-Reply-To:	<CALSZ9gpoxnz9V-CbisKqmdwQyTtVf6G9nCe2Wt=4p4su-afFBQ@mail.gmail.com>
X-PM-EL-Spam-Prob:	X: 10%
Reply-To:	geda-user AT delorie DOT com

On 03/29/2014 10:36 AM, Rob Butts wrote:
> I have a short 8kHz 16 bit wav pcm file that I converted to an 8kHz 16 bit
> unsigned C numerical array.  I'm using a 12 bit dac so I need to convert
> the 16 bit numerical array to a 12 bit numerical array.
>
> Before I get started is this just a matter of shifting out the four most
> significant bits of the binary 16 bit value?
>
That depends on the nature of the signal. Usually the noise is mostly in 
the low order bits so you may want to dump at least one or 2 of those. 
But first, you may also want to examine the high order bits. Depending 
upon the initial gain settings when the data was sampled, one or 2 of 
the high order bits may be all the same anyway. In either case, I think 
I would do this in 2 stages. First, shift up to get rid of unused 
dynamic range at the top end. Then throw away the rest at the low end 
where the noise is. You may want to signal average the low bits, say 3 
bits into 1 or 4 bits into 2

Steve Besch

-- 
fictio cedit veritati

- Raw text -