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SPU audio latency improvements 

Basically reverts audio buffer handling to what it was before commit 05b94ef, but with the mutexes kept for thread safety (which the referenced commit was trying to do).

The SPU audio buffer should still be thread-safe in theory... right?
This commit is contained in:
Sparronator9999 2025-03-07 12:38:14 +11:00
parent 63b468927e
commit 4e9a724751
No known key found for this signature in database
GPG Key ID: E39582019E956F00
3 changed files with 38 additions and 65 deletions
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1
src/NDS.cpp
View File

@ -1025,7 +1025,6 @@ u32 NDS::RunFrame()
ARM7Timestamp-SysTimestamp,
GPU.GPU3D.Timestamp-SysTimestamp);
#endif
SPU.TransferOutput();
break;
}

90
src/SPU.cpp
View File

@ -207,11 +207,10 @@ SPU::SPU(melonDS::NDS& nds, AudioBitDepth bitdepth, AudioInterpolation interpola
ApplyBias = true;
Degrade10Bit = false;
memset(OutputFrontBuffer, 0, 2*OutputBufferSize*2);
memset(OutputBuffer, 0, 2*OutputBufferSize*2);
OutputBackbufferWritePosition = 0;
OutputFrontBufferReadPosition = 0;
OutputFrontBufferWritePosition = 0;
OutputBufferReadPos = 0;
OutputBufferWritePos = 0;
}
SPU::~SPU()
@ -242,11 +241,10 @@ void SPU::Reset()
void SPU::Stop()
{
Platform::Mutex_Lock(AudioLock);
memset(OutputFrontBuffer, 0, 2*OutputBufferSize*2);
memset(OutputBuffer, 0, 2*OutputBufferSize*2);
OutputBackbufferWritePosition = 0;
OutputFrontBufferReadPosition = 0;
OutputFrontBufferWritePosition = 0;
OutputBufferReadPos = 0;
OutputBufferWritePos = 0;
Platform::Mutex_Unlock(AudioLock);
}
@ -942,67 +940,49 @@ void SPU::Mix(u32 dummy)
rightoutput &= 0xFFFFFFC0;
}
// OutputBufferFrame can never get full because it's
// transfered to OutputBuffer at the end of the frame
// FIXME: apparently this does happen!!!
if (OutputBackbufferWritePosition * 2 < OutputBufferSize - 1)
Platform::Mutex_Lock(AudioLock);
OutputBuffer[OutputBufferWritePos++] = leftoutput >> 1;
OutputBuffer[OutputBufferWritePos++] = rightoutput >> 1;
OutputBufferWritePos &= ((2*OutputBufferSize)-1);
if (OutputBufferWritePos == OutputBufferReadPos)
{
OutputBackbuffer[OutputBackbufferWritePosition ] = leftoutput >> 1;
OutputBackbuffer[OutputBackbufferWritePosition + 1] = rightoutput >> 1;
OutputBackbufferWritePosition += 2;
// advance the read position too, to avoid losing the entire FIFO
OutputBufferReadPos += 2;
OutputBufferReadPos &= ((2*OutputBufferSize)-1);
}
Platform::Mutex_Unlock(AudioLock);
NDS.ScheduleEvent(Event_SPU, true, 1024, 0, 0);
}
void SPU::TransferOutput()
{
Platform::Mutex_Lock(AudioLock);
for (u32 i = 0; i < OutputBackbufferWritePosition; i += 2)
{
OutputFrontBuffer[OutputFrontBufferWritePosition ] = OutputBackbuffer[i ];
OutputFrontBuffer[OutputFrontBufferWritePosition + 1] = OutputBackbuffer[i + 1];
OutputFrontBufferWritePosition += 2;
OutputFrontBufferWritePosition &= OutputBufferSize*2-1;
if (OutputFrontBufferWritePosition == OutputFrontBufferReadPosition)
{
// advance the read position too, to avoid losing the entire FIFO
OutputFrontBufferReadPosition += 2;
OutputFrontBufferReadPosition &= OutputBufferSize*2-1;
}
}
OutputBackbufferWritePosition = 0;
Platform::Mutex_Unlock(AudioLock);;
}
void SPU::TrimOutput()
{
Platform::Mutex_Lock(AudioLock);
const int halflimit = (OutputBufferSize / 2);
int readpos = OutputFrontBufferWritePosition - (halflimit*2);
int readpos = OutputBufferWritePos - (halflimit*2);
if (readpos < 0) readpos += (OutputBufferSize*2);
OutputFrontBufferReadPosition = readpos;
OutputBufferReadPos = readpos;
Platform::Mutex_Unlock(AudioLock);
}
void SPU::DrainOutput()
{
Platform::Mutex_Lock(AudioLock);
OutputFrontBufferWritePosition = 0;
OutputFrontBufferReadPosition = 0;
OutputBufferReadPos = 0;
OutputBufferWritePos = 0;
Platform::Mutex_Unlock(AudioLock);
}
void SPU::InitOutput()
{
Platform::Mutex_Lock(AudioLock);
memset(OutputBackbuffer, 0, 2*OutputBufferSize*2);
memset(OutputFrontBuffer, 0, 2*OutputBufferSize*2);
OutputFrontBufferReadPosition = 0;
OutputFrontBufferWritePosition = 0;
memset(OutputBuffer, 0, 2*OutputBufferSize*2);
OutputBufferReadPos = 0;
OutputBufferWritePos = 0;
Platform::Mutex_Unlock(AudioLock);
}
@ -1011,10 +991,10 @@ int SPU::GetOutputSize() const
Platform::Mutex_Lock(AudioLock);
int ret;
if (OutputFrontBufferWritePosition >= OutputFrontBufferReadPosition)
ret = OutputFrontBufferWritePosition - OutputFrontBufferReadPosition;
if (OutputBufferWritePos >= OutputBufferReadPos)
ret = OutputBufferWritePos - OutputBufferReadPos;
else
ret = (OutputBufferSize*2) - OutputFrontBufferReadPosition + OutputFrontBufferWritePosition;
ret = (OutputBufferSize*2) - OutputBufferReadPos + OutputBufferWritePos;
ret >>= 1;
@ -1043,10 +1023,10 @@ void SPU::Sync(bool wait)
{
Platform::Mutex_Lock(AudioLock);
int readpos = OutputFrontBufferWritePosition - (halflimit*2);
int readpos = OutputBufferWritePos - (halflimit*2);
if (readpos < 0) readpos += (OutputBufferSize*2);
OutputFrontBufferReadPosition = readpos;
OutputBufferReadPos = readpos;
Platform::Mutex_Unlock(AudioLock);
}
@ -1055,7 +1035,7 @@ void SPU::Sync(bool wait)
int SPU::ReadOutput(s16* data, int samples)
{
Platform::Mutex_Lock(AudioLock);
if (OutputFrontBufferReadPosition == OutputFrontBufferWritePosition)
if (OutputBufferReadPos == OutputBufferWritePos)
{
Platform::Mutex_Unlock(AudioLock);
return 0;
@ -1063,13 +1043,11 @@ int SPU::ReadOutput(s16* data, int samples)
for (int i = 0; i < samples; i++)
{
*data++ = OutputFrontBuffer[OutputFrontBufferReadPosition];
*data++ = OutputFrontBuffer[OutputFrontBufferReadPosition + 1];
*data++ = OutputBuffer[OutputBufferReadPos++];
*data++ = OutputBuffer[OutputBufferReadPos++];
OutputBufferReadPos &= ((2*OutputBufferSize)-1);
OutputFrontBufferReadPosition += 2;
OutputFrontBufferReadPosition &= ((2*OutputBufferSize)-1);
if (OutputFrontBufferWritePosition == OutputFrontBufferReadPosition)
if (OutputBufferWritePos == OutputBufferReadPos)
{
Platform::Mutex_Unlock(AudioLock);
return i+1;

12
src/SPU.h
View File

@ -241,7 +241,6 @@ public:
int GetOutputSize() const;
void Sync(bool wait);
int ReadOutput(s16* data, int samples);
void TransferOutput();
u8 Read8(u32 addr);
u16 Read16(u32 addr);
@ -251,14 +250,11 @@ public:
void Write32(u32 addr, u32 val);
private:
static const u32 OutputBufferSize = 2*2048;
static const u32 OutputBufferSize = 2*1024; // TODO: configurable audio buffer sizes?
melonDS::NDS& NDS;
s16 OutputBackbuffer[2 * OutputBufferSize] {};
u32 OutputBackbufferWritePosition = 0;
s16 OutputFrontBuffer[2 * OutputBufferSize] {};
u32 OutputFrontBufferWritePosition = 0;
u32 OutputFrontBufferReadPosition = 0;
s16 OutputBuffer[2 * OutputBufferSize] {};
u32 OutputBufferWritePos = 0;
u32 OutputBufferReadPos = 0;
Platform::Mutex* AudioLock;