libretro/FBNeo
1
0
Fork 0
mirror of https://github.com/libretro/FBNeo.git synced 2024-11-24 01:19:46 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

driver-level hiss-removal fix for BurgerTime

Browse Source
This commit is contained in:
dinkc64 2016-06-08 23:33:14 +00:00
parent 6ad8b56a83
commit 891057c8bc
1 changed files with 63 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

68
src/burn/drv/pre90s/d_btime.cpp
View File

@ -1209,6 +1209,60 @@ static UINT8 btime_sound_read(UINT16 address)
return 0;
}
/*
dink's notes on the horrible migraine-inducing high-pitched hissing noise
for a note-off, burgertime's audiocpu sends a command with fine/coarse tuning
set to 0 to each channel. Right after this, it sends a volume command for
that channel. The ay8910 soundcore (old and recent) treats a tuning command
of 0 as a very high pitched noise. theres also a funny bug in the 8910
emulator: if you remove the check for a 0 fine/coarse tuning - to actually
allow for a tune of 0 - it will actually lock up while rendering the samples.
see: if (PSG->PeriodA == 0) PSG->PeriodA = PSG->UpdateStep;
what I do to get around making any changes to the ay8910 core is look for the
fine/coarse tuning value of 0 being sent to each of the first ay's 3 channels
and set the volume down to 0. The next command is always a volume, so we just
change the next data command to 0.
0x02: 0. 0x01: 0. AF: 0 AC: 0.
0x02: 1. 0x01: 0. AF: 0 AC: 0.
0x02: 2. 0x01: 0. BF: 0 BC: 0.
0x02: 3. 0x01: 0. BF: 0 BC: 0.
0x02: 4. 0x01: 0. CF: 0 CC: 0.
0x02: 5. 0x01: 0. CF: 0 CC: 0.
*/
static UINT8 last01[3] = {0xff,0xff};
static UINT8 last02[3] = {0xff,0xff};
static UINT8 ignext = 0;
static void checkhiss_add02(UINT8 data)
{
last02[1] = last02[0];
last02[0] = data;
}
static void checkhiss_and_add01(UINT8 data)
{
last01[1] = last01[0];
last01[0] = data;
if (last01[0] == 0 && last02[0] == 1 && last01[1] == 0 && last02[1] == 0)
{
ignext = 1; // next command will be VolA
}
if (last01[0] == 0 && last02[0] == 3 && last01[1] == 0 && last02[1] == 2)
{
ignext = 1; // next command will be VolB
}
if (last01[0] == 0 && last02[0] == 5 && last01[1] == 0 && last02[1] == 4)
{
ignext = 1; // next command will be VolC
}
}
static void btime_sound_write(UINT16 address, UINT8 data)
{
if (address >= 0x0000 && address <= 0x1fff) {
@ -1217,10 +1271,18 @@ static void btime_sound_write(UINT16 address, UINT8 data)
switch (address >> 13)
{
case 0x01:
//bprintf(0, _T("0x01: %X. "), data);
if (ignext) {
data = 0; // set volume to 0
ignext = 0;
}
AY8910Write(0, ~((address>>13)-1) & 1, data);
checkhiss_and_add01(data);
return;
case 0x02:
//bprintf(0, _T("0x02: %X. "), data);
AY8910Write(0, ~((address>>13)-1) & 1, data);
checkhiss_add02(data);
return;
case 0x03:
AY8910Write(1, ~((address>>13)-1) & 1, data);
@ -1831,8 +1893,6 @@ static INT32 BtimeInit()
AY8910SetAllRoutes(0, 0.20, BURN_SND_ROUTE_BOTH);
AY8910SetAllRoutes(1, 0.20, BURN_SND_ROUTE_BOTH);
ay8910burgertime_mode = 1;
audio_nmi_type = AUDIO_ENABLE_DIRECT;
GenericTilesInit();
@ -1973,8 +2033,6 @@ static INT32 DrvExit()
M6502Exit();
ay8910burgertime_mode = 0;
AY8910Exit(0);
AY8910Exit(1);
@ -2320,7 +2378,7 @@ static INT32 DiscoDraw()
return 0;
}
#define FILTERDEBUG 1
#define FILTERDEBUG 0
#if FILTERDEBUG
extern int counter; // save for later debugging/tweaking. -dink