MU-law and A-law tables in the DSP56000

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2 total messages Started by Bartjan Wattel Tue, 15 Dec 1992 15:38

#1850

Author: Bartjan Wattel
Date: Tue, 15 Dec 1992 15:38

18 lines
1232 bytes

Hi,

I'm starting on studying the DSP56000 for an exam at the Eindhoven University
of Technology (the Netherlands). I ran into the terms 'MU-law' and 'A-law'.
The X data ROM in the DSP56000 seems to be factory programmed with these
tables. 

Could anybody tell me in what way these tables can be used ? I have the idea
that the tables have something to do with (data)compression, but I might be
wrong...

Bartjan Wattel at Eindhoven University of Technology, the Netherlands
(Email: bartjan@blade.stack.urc.tue.nl)
--------------------------------------------------------------------------------

     "Why is it that we rejoice at a birth and grieve at a funeral?  It is
                    because we are not the person involved"
                                      -- Mark Twain

Re: MU-law and A-law tables in the DSP56000

#1889

Author: Paul Bame
Date: Tue, 22 Dec 1992 00:21

19 lines
1342 bytes

In comp.dsp, bartjan@blade.stack.urc.tue.nl (Bartjan Wattel) writes:

> I'm starting on studying the DSP56000 for an exam at the Eindhoven University
> of Technology (the Netherlands). I ran into the terms 'MU-law' and 'A-law'.

> Could anybody tell me in what way these tables can be used ? I have the idea
> that the tables have something to do with (data)compression, but I might be
> wrong...

These are defined in section G.711 in the CCITT "Blue Book" (I think I've
got that right).  Mu-law effectively allows 14 bits of dynamic range
to be stuffed into 8 bits and is rather like a signed logarithm - but it's
not really a logarithm which is why conversion tables are used.  A-law
is a variant of mu-law with which I'm unfamiliar which is also defined in
G.711.  If you have an HP workstation with audio I/O hardware, chances are
good it understands mu-law, a-law, and linear encoding (which hasn't
made it into the FAQ yet).

	-Paul Bame

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