[PATCH] Update protocols to support tone generation.

[Bohdan R . Rau]

On Sun, 24 Oct 2010 02:38:09 -0500, Christopher Brannon
<chris at the-brannons.com> wrote:
> "Bohdan R. Rau" <ethanak at polip.com> writes:
> 
>> Working generator is in http://tts.polip.com/files/tonegen.tgz
>> Supports ADSR, frequency pair and three waveforms.
> 
> This looks neat, and the code is still small.
> Do you have any handy references describing what the ADSR parameters do?

ADSR means "Attack-Decay-Sustain-Release" (four phases of amplitude
contour used in almost all music synthesizers).
Simple and good description you can find at
http://en.wikipedia.org/wiki/Synthesizer#ADSR_envelope

Originally release time is not counted into duration. I changed this
behaviour because we are interested in total sound duration. Also, as
parameters may be recomputed to fit in given duration, we can set release
as something big (like 2000 msec) to have sustain phase disabled.


For example: ADSR of simple 'beep' is 0 0 1000 0. But 10 0 1000 10 makes
the 'beep' more ear-friendly.


Also, original synthesizers operates on logarythmic scale, not amplitude.
For out goals amplitude is enough.

BTW. generator may be simply rewritten to use internal function instead of
modf (in this case generator won't need math library) or even for integer
arithmethic.

ethanak
-- 
http://milena.polip.com/ - Pa pa, Ivonko!