Re: [linux-audio-dev] 24 bits, 2's complement - help!

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Subject: Re: [linux-audio-dev] 24 bits, 2's complement - help!
From: Juhana Sadeharju (kouhia_AT_nic.funet.fi)
Date: su tammi  16 2000 - 07:30:27 EST


>From: Benno Senoner <sbenno_AT_gardena.net>
>
>For dithering use the following: assume you have the 24value
>(stored in a 32bit int signed).
>generate a table ( 100k values or so) with 8bit random values ranging
>from -128 to +127.
>
>add this random number to the 24bit sample data,

Tables are probably no no; specially if used in driver.

As far as I understand it is more efficient to compute the random
numbers than read them from a table. You should also pick up two
random numbers from the generator, sum them, and add the sum to
the audio sample. But test if one number per sample works good enough.

Check out some shaped ditherers from Sonic Flow if needed.

I'm sure it can be done without any clipping tests which sure degrades
the optimization.

Juhana


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