Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

improve apu pulse channel nonlinear mixing precision #89

Closed
wants to merge 2 commits into from
Closed

improve apu pulse channel nonlinear mixing precision #89

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
245f03a
improve apu pulse channels non-linear mixing precision
tsone Jan 24, 2025
fbe2e21
change square_table lookup generation use (1<<17)
tsone Feb 4, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
23 changes: 11 additions & 12 deletions xgm/devices/Sound/nes_apu.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -147,19 +147,18 @@ namespace xgm

if(option[OPT_NONLINEAR_MIXER])
{
INT32 voltage = square_table[out[0] + out[1]];
m[0] = out[0] << 6;
m[1] = out[1] << 6;
INT32 ref = m[0] + m[1];
INT32 ref = out[0] + out[1];
if (ref > 0)
{
m[0] = (m[0] * voltage) / ref;
m[1] = (m[1] * voltage) / ref;
INT32 voltage = square_table[ref];
m[0] = (out[0] * voltage) / ref;
m[1] = (out[1] * voltage) / ref;
}
else
{
m[0] = voltage;
m[1] = voltage;
// square_table[0] = 0;
m[0] = 0;
m[1] = 0;
}
}
else
Expand All @@ -170,11 +169,11 @@ namespace xgm

b[0] = m[0] * sm[0][0];
b[0] += m[1] * sm[0][1];
b[0] >>= 7;
b[0] >>= 11;

b[1] = m[0] * sm[1][0];
b[1] += m[1] * sm[1][1];
b[1] >>= 7;
b[1] >>= 11;

return 2;
}
Expand All @@ -190,8 +189,8 @@ namespace xgm
option[OPT_NEGATE_SWEEP_INIT] = false;

square_table[0] = 0;
for(int i=1;i<32;i++)
square_table[i]=(INT32)((8192.0*95.88)/(8128.0/i+100));
for(int i=1;i<32;i++)
square_table[i]=(INT32)round(((1<<17)*95.88)/(8128.0/i+100));

square_linear = square_table[15]; // match linear scale to one full volume square of nonlinear

Expand Down