Le 11/05/2011 10:36, Invisible a écrit :
> 
> I would suggest, however, that 4 bits/sample would be inadequate for
> audio applications.

For a linear PCM, yes.
But one of the latest format (SACD) use only 1 bit/sample (at a silly
high sampling rate) in a non-PCM storage.
(in fact the bit is simply a up/down delta, and it make easy to get ride
of the digital to analogue converter in the mass production of player:
use the bit to drive digitally a transistor, accumulate output in a
capacitor, the connection to the ear-set is done directly on the
capacitor (volume is set by resistor on the transistor's upstream))
2 cheap components (or even less if you can fake the capacitor with
circuitry) to replace an expensive DAC.

Delta Sigma encoding is really painful to convert back accurately in PCM.
And it is even worse with Adaptive Delta Sigma (where the unit of the
current sample is dependent of the previous samples), but they requires
far less bits than PCM.
(Adaptive Delta Sigma need more than 1 bit)

-- 
Software is like dirt - it costs time and money to change it and move it
around.

Just because you can't see it, it doesn't weigh anything,
and you can't drill a hole in it and stick a rivet into it doesn't mean
it's free.

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