Rate change without glitches

ExistentialAudio · Feb 7, 2022 · d9f2b7a · d9f2b7a
1 parent 54ecf85
commit d9f2b7a
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Showing 2 changed files with 15 additions and 5 deletions.
diff --git a/BlackHole/BlackHole.c b/BlackHole/BlackHole.c
@@ -224,6 +224,7 @@ static OSStatus	BlackHole_Initialize(AudioServerPlugInDriverRef inDriver, AudioS
 	Float64 theHostClockFrequency = (Float64)theTimeBaseInfo.denom / (Float64)theTimeBaseInfo.numer;
 	theHostClockFrequency *= 1000000000.0;
 	gDevice_HostTicksPerFrame = theHostClockFrequency / gDevice_SampleRate;
+	gDevice_AdjustedTicksPerFrame = gDevice_HostTicksPerFrame - gDevice_HostTicksPerFrame/100.0 * 2.0*(gPitch_Adjust - 0.5);
 
     // DebugMsg("BlackHole theTimeBaseInfo.numer: %u \t theTimeBaseInfo.denom: %u", theTimeBaseInfo.numer, theTimeBaseInfo.denom);
 
@@ -357,6 +358,7 @@ static OSStatus	BlackHole_PerformDeviceConfigurationChange(AudioServerPlugInDriv
     Float64 theHostClockFrequency = (Float64)theTimeBaseInfo.denom / (Float64)theTimeBaseInfo.numer;
 	theHostClockFrequency *= 1000000000.0;
 	gDevice_HostTicksPerFrame = theHostClockFrequency / gDevice_SampleRate;
+	gDevice_AdjustedTicksPerFrame = gDevice_HostTicksPerFrame - gDevice_HostTicksPerFrame/100.0 * 2.0*(gPitch_Adjust - 0.5);
 
 	//	unlock the state mutex
 	pthread_mutex_unlock(&gPlugIn_StateMutex);
@@ -3695,6 +3697,7 @@ static OSStatus	BlackHole_SetControlPropertyData(AudioServerPlugInDriverRef inDr
 						if(gPitch_Adjust != theNewPitch)
 						{
 							gPitch_Adjust = theNewPitch;
+							gDevice_AdjustedTicksPerFrame = gDevice_HostTicksPerFrame - gDevice_HostTicksPerFrame/100.0 * 2.0*(gPitch_Adjust - 0.5);
 							*outNumberPropertiesChanged = 1;
 							outChangedAddresses[0].mSelector = kAudioStereoPanControlPropertyValue;
 							outChangedAddresses[0].mScope = kAudioObjectPropertyScopeGlobal;
@@ -3703,9 +3706,10 @@ static OSStatus	BlackHole_SetControlPropertyData(AudioServerPlugInDriverRef inDr
 					}
 					else
 					{
-						if(gVolume_Master_Value != theNewPitch)
+						if(gPitch_Adjust != theNewPitch)
 						{
 							gPitch_Adjust = theNewPitch;
+							gDevice_AdjustedTicksPerFrame = gDevice_HostTicksPerFrame - gDevice_HostTicksPerFrame/100.0 * 2.0*(gPitch_Adjust - 0.5);
 							*outNumberPropertiesChanged = 1;
 							outChangedAddresses[0].mSelector = kAudioStereoPanControlPropertyValue;
 							outChangedAddresses[0].mScope = kAudioObjectPropertyScopeGlobal;
@@ -3765,6 +3769,7 @@ static OSStatus	BlackHole_StartIO(AudioServerPlugInDriverRef inDriver, AudioObje
 		gDevice_NumberTimeStamps = 0;
 		gDevice_AnchorSampleTime = 0;
 		gDevice_AnchorHostTime = mach_absolute_time();
+		gDevice_PreviousTicks = 0;
 
 		// allocate ring buffer
 		gRingBuffer = calloc(kRing_Buffer_Frame_Size * kNumber_Of_Channels, sizeof(Float32));
@@ -3841,7 +3846,8 @@ static OSStatus	BlackHole_GetZeroTimeStamp(AudioServerPlugInDriverRef inDriver,
 	OSStatus theAnswer = 0;
 	UInt64 theCurrentHostTime;
 	Float64 theHostTicksPerRingBuffer;
-	Float64 theHostTickOffset;
+	Float64 theAdjustedTicksPerRingBuffer;
+	Float64 theNextTickOffset;
 	UInt64 theNextHostTime;
 
 	//	check the arguments
@@ -3856,20 +3862,22 @@ static OSStatus	BlackHole_GetZeroTimeStamp(AudioServerPlugInDriverRef inDriver,
 
 	//	calculate the next host time
 	theHostTicksPerRingBuffer = gDevice_HostTicksPerFrame * ((Float64)kDevice_RingBufferSize);
+	theAdjustedTicksPerRingBuffer = gDevice_AdjustedTicksPerFrame * ((Float64)kDevice_RingBufferSize);
 
-	theHostTickOffset = ((Float64)(gDevice_NumberTimeStamps + 1)) * theHostTicksPerRingBuffer;
+	theNextTickOffset = gDevice_PreviousTicks + theAdjustedTicksPerRingBuffer;
 
-	theNextHostTime = gDevice_AnchorHostTime + ((UInt64)theHostTickOffset);
+	theNextHostTime = gDevice_AnchorHostTime + ((UInt64)theNextTickOffset);
 
 	//	go to the next time if the next host time is less than the current time
 	if(theNextHostTime <= theCurrentHostTime)
 	{
 		++gDevice_NumberTimeStamps;
+		gDevice_PreviousTicks = theNextTickOffset;
 	}
 
 	//	set the return values
 	*outSampleTime = gDevice_NumberTimeStamps * kDevice_RingBufferSize;
-	*outHostTime = gDevice_AnchorHostTime + (((Float64)gDevice_NumberTimeStamps) * theHostTicksPerRingBuffer);
+	*outHostTime = gDevice_AnchorHostTime + gDevice_PreviousTicks;
 	*outSeed = 1;
 
     // DebugMsg("SampleTime: %f \t HostTime: %llu", *outSampleTime, *outHostTime);

diff --git a/BlackHole/BlackHole.h b/BlackHole/BlackHole.h
@@ -138,6 +138,8 @@ static Float64                      gDevice_SampleRate                  = 44100.
 static UInt64                       gDevice_IOIsRunning                 = 0;
 static const UInt32                 kDevice_RingBufferSize              = 16384;
 static Float64                      gDevice_HostTicksPerFrame           = 0.0;
+static Float64                      gDevice_AdjustedTicksPerFrame       = 0.0;
+static Float64                      gDevice_PreviousTicks               = 0.0;
 static UInt64                       gDevice_NumberTimeStamps            = 0;
 static Float64                      gDevice_AnchorSampleTime            = 0.0;
 static UInt64                       gDevice_AnchorHostTime              = 0;