Re: [Qemu-devel] [PATCH] PC speaker emulation (fixed point)

[Sebastian Kaliszewski]

Joachim Henke wrote:
> I still prefer using a sine wave, it sounds more smooth and won't  hurt 
> our ears (and speakers) too much.

Well, it sounds rather dull, and even worse, on non hi-fi computer speakers 
(which is 90% of PC users use) low frequencies (<100Hz) are simply 
unhearable (since equipment is very poor at transmitting those frequencies).
While harmonics rich square wave will be hearable, due to harmonics being 
hearable.

> I don't think that people want  to 
> play square waves, when they have their PC connected to their hifi  
> system 

Many people connected their Apples IIs, Commodores 64s & Ataris 800s to 
their Hi-Fi equipment, and those didn't break their ears nor equipment.


> (c: The main purpose of the PC speaker is to generate tones  and 
> many programmers used it to play melodies. Why shouldn't we take  this 
> chance to make it sound as good as we can manage it?

Exactly. No real musical instrument generates sine wawes. Moreover as 
various psyhoacustics reaserch shows, using pure sine waes changes our 
perception of chords & harmony. Then 95% of home sound equipment degrages 
and attenuates low frequencies below 40-50Hz.

If Qemu is for emulation it should emulate things as close to reality as 
feasible. Why do more work & intentionally break the close emulation, while 
it's even easier to acheive?


[snip]
> However, this approach should still be sufficient for our purpose.  Most 
> programs don't use too low frequencies, and if they do, people  probably 
> won't notice.

Many PC games used low frequencies to emit varius buzzes and stuff (like 
engine noise). With sine wave those will be completely broken.


rgds
--
Sebastian Kaliszewski