14Bit amiga sound

[none]

While this news group seems pretty dead I'll try any way...

Can anybody enlighten me how 14Bit sound is done on amiga hardware?
As far as I've been able to dig out, it seems that some manipulation of
the 6 bit volume registers is performed? But exactly how? I've been
searching on google and google groups but come up with zip.

Thanks!

--
Sune

[Jukka Aho]

none" <""sunegn\"@(none) wrote:

Since the Amiga has four sound channels (two of which are hardwired to
the left audio output and two of which are hardwired to the right audio
output), could it be that the two channels on the same side are used
together in some fashion?

For example, one of the channels could provide the subtle dynamics (less
significant bits) to the sound, and the other one the louder, coarser
ones.

(Just a thought, I don't really know.)

--
znark

[Antti Pyykko]

On 2007-02-08, none <""> wrote:
> Can anybody enlighten me how 14Bit sound is done on amiga hardware?

By combining two channels as one. The other channels plays normal 8bit
sound with full volume, the other channel has only the least significant
bit set and has it's volume register poked. This way the least
significant bit can have 6 bits worth of values, because the Paula
has 6-bit volume register. 8 PCM bits + 6 volume bits = 14bit output.

--

[none]

Antti Pyykko skrev:

So let me see if I got this right! You dump the lower [0-7] bits as PCM
bits on, say, channel 0 and use the remaining upper [8-13] bits to
'modulate' the volume of, say, channel 1?

I'm not quite sure I completely understands why this work?

--
Regards,
Sune

[Torfinn Ingolfsen]

Perhaps the channels are additively mixed?
--
Torfinn Ingolfsen,
Norway

[Antti Pyykko]

On 2007-02-08, none <""> wrote:
> So let me see if I got this right! You dump the lower [0-7] bits as PCM
> bits on, say, channel 0 and use the remaining upper [8-13] bits to
> 'modulate' the volume of, say, channel 1?

Of the 14-bit sample, you dump the 8 most significant bits from the sample
as PCM bits on channel 0 with full volume. Then you 'modulate' the 6-bit
volume register of channel 1น with the 6 least significant bits from the
sample. The Channel 1 will constantly have only its least significant PCM
bit set.

<Chan0-><Chn1>
01101010110110
<-PCM--><Vol->

น In reality, you would use channel pairs 0+3 and 1+2 because that's how
they're paired to the left and right RCA outputs.

--

[none]

Antti Pyykko skrev:

Okay, thanks - got it! So doing 14 bit leaves us with two 'hardware'
channels. What are the upper limit of software channels on a, say, 1200?
The case is, I'm pulling out my old 1200 with a 030 accelerator and
would like to have at bit of fun and I was thinking maybe 8 channel
14Bit sound would be cool :)

--
Sune