[Coladam] More about tone channels attenuation (volume) -and- digital sounds (PART 2)

Daniel Bienvenu newcoleco at yahoo.fr
Fri Dec 11 00:06:25 CET 2009


The following link is a sample running on a real ColecoVision. The audio sample plays first a 22K ROM of raw bytes using the 64 values strategy explained in my first messages about sound channel attenuations, then it plays the same thing but with the 46 values strategy talked in my last message, but it still a 22K ROM file. You'll hear first the noisy artefacts I've called glitches because it's caused by glitches when switching from one volume level to another one. Then you'll hear an almost perfect sound quality, but I assure you that this is real.

http://www.ccjvq.com/newcoleco/sndtest.mp3

Encoding into nibbles and decoding them fast enough is the next step. This will reduce the ROM fil to 11K and also the sound quality because of the lossy compression technic.

A third step, if I can do it, will be to add an extra compression, like RLE compression, to squeeze even more the data into the ROM file, maybe getting a 8K ROM instead of 11K.

Have a nice day!

Daniel

--- En date de : Jeu 10.12.09, Daniel Bienvenu <newcoleco at yahoo.fr> a écrit :

> De: Daniel Bienvenu <newcoleco at yahoo.fr>
> Objet: [Coladam] More about tone channels attenuation (volume) -and- digital sounds
> À: "Ronald Mitchell" <bytehacker at tallcedarskennels.com>
> Cc: coladam at adamcon.org, colecoprogramming at yahoogroups.com
> Date: Jeudi 10 Décembre 2009, 15h24
> Well, after more calculations, the
> only way I've find out to eliminate the glitches that cause
> the clearly audible periodic noise in the background, is to
> reduce the combinations by eliminating the "not wanted" ones
> that cause these glitches.
> 
> The best compromise is using 46 values as follow :
> 
> F F F -> 0,000000000000000
> E F F -> 0,013270239018450
> E E F -> 0,026540478036900
> E E E -> 0,039810717055350
> D E E -> 0,043246719157809
> D D E -> 0,046682721260268
> D D D -> 0,050118723362727
> C D D -> 0,054444393724491
> C C D -> 0,058770064086255
> C C C -> 0,063095734448019
> B C C -> 0,068541430789489
> B B C -> 0,073987127130959
> B B B -> 0,079432823472428
> A B B -> 0,086288548981619
> A A B -> 0,093144274490809
> A A A -> 0,100000000000000
> 9 A A -> 0,108630847059806
> 9 9 A -> 0,117261694119611
> 9 9 9 -> 0,125892541179417
> 8 9 9 -> 0,136758133868315
> 8 8 9 -> 0,147623726557213
> 8 8 8 -> 0,158489319246111
> 7 8 8 -> 0,172168289996370
> 7 7 8 -> 0,185847260746629
> 7 7 7 -> 0,199526231496888
> 6 7 7 -> 0,216747035381578
> 6 6 7 -> 0,233967839266268
> 6 6 6 -> 0,251188643150958
> 5 6 6 -> 0,272868350772918
> 5 5 6 -> 0,294548058394878
> 5 5 5 -> 0,316227766016838
> 4 5 5 -> 0,343520900862391
> 4 4 5 -> 0,370814035707944
> 4 4 4 -> 0,398107170553497
> 3 4 4 -> 0,432467191578089
> 3 3 4 -> 0,466827212602681
> 3 3 3 -> 0,501187233627272
> 2 3 3 -> 0,544443937244913
> 2 2 3 -> 0,587700640862553
> 2 2 2 -> 0,630957344480193
> 1 2 2 -> 0,685414307894889
> 1 1 2 -> 0,739871271309585
> 1 1 1 -> 0,794328234724282
> 0 1 1 -> 0,862885489816188
> 0 0 1 -> 0,931442744908094
> 0 0 0 -> 1,000000000000000
> 
> It's not well distributed but the noisy glitches are no
> more an issue. A first test confirm this.
> 
> So, now, the next step is encoding into nibbles instead of
> 5 or 6 bits vlues.
> 
> Have a nice day!
> 
> Daniel 
> 
> 
> 
>       
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