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Discussion about software development for the old-school Gameboys, ranging from the "Gray brick" to Gameboy Color
(Launched in 2008)

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#1 2017-03-14 16:08:52

New member
Registered: 2016-10-27
Posts: 1

GB square wave channel 1

Hi guys!

I'm developing my own GB emulator for fun but i'm stuck with a problem with audio and i have no clue how to get rid of it

The issue is related to the Blues Brothers game

It seems like, during the opening music theme, square wave channel number one produce an unwanted noise whilst no other emulator produces

After some second of correctly played music, registers NR13 and NR14 are written with 0xFE (13) and 87 (14)... envelope period is set to zero and so it is sweep...

this means the output of channel one is set to a frequency of 2046 (3 lower bit of NR14 concatenated o NR13 -> 111 | 11111110 = 2046)
and what expect is to hear a sound with very high pitch

and my emulator does so, but it's clearly wrong.... plus, other emus seems to ignore to output that high pitch note

my question is... there's some kind of filter that get rid of high frequencies? Am i doing someting wrong?

Suggestions? Advices?



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