Another audio (voice) compression for CV games?

[newcoleco]

We all know the typical encoding-decoding the variation of volumes (with or without compression) in order to achieve the effect of a digitalised audio clips like some music or speech (like games featuring Sam). And I've talked a bit about using very simple wavelets to achieve digital audio compression. But I've came accross a method that we didn't tried yet used apparently in some arcade machines, pinballs and as a way of transmitting voice with a bluetooth device.

 

The idea is simple : Delta modulation? or better Continuously variable slope in delta modulation? Yeah! instead of encoding the various values of the audio wave signal or even the differences between consecutive values in that audio wave signal (aka delta), why not let the decoder set the slope value while decoding all the 0s and 1s as respectively plus or minus this delta value that changes dynamicaly?

 

This idea might sounds awkward because it leads to a lack of audio quality for the general usage of digitalized sounds in CV games. But, this method of encoding the audio signal is used with success for things as simple as human speech. And since this method reduce the need to encode bits to only 1bit for every new value of the audio wave signal right there it's mission accomplished for data compression which is quite interesting. So, could it be done and works fine for a CV game? Maybe we will find out in the near future.

 

With this approach of audio compression, if done well, a game like Space Taxi might be ported as a regular 32KB CV cartridge no problem because it kinda multiplies by four the number of short voice clips you can squeeze into the same amount of memory.

[Pixelboy]

It would be interesting to see if this programming technique could help to reproduce the functionaities of the Intellivoice module.

[youki]

I think Space Taxi can be ported already on 32k cartridge with digital speech using current technic.

 

Something if i had time i would try , is to analyze as software voice synthetiser based on phonems of game "Le manoir de morteville" is done. Because the result is very good even on 8 bit machine like the Amstrad CPC or even on a 8088 PC with a simple speaked (no sound card).

 

La version 8 bit Amstrad CPC (Z80 machine):

 

http://www.dailymoti...es#.UMMEnjLB-uI

 

Version PC :

 

http://www.youtube.com/watch?v=304tmvLbdaw

 

Version ST :

 

http://www.youtube.com/watch?v=v1ID2QGWyQc

Edited December 8, 2012 by youki