Keep track of a device clock time, based on the number of samples processed

3 files changed, 39 insertions, 0 deletions

diff --git a/Alc/ALc.c b/Alc/ALc.c
index 7d8f14cd..ad8b4286 100644
--- a/Alc/ALc.c
+++ b/Alc/ALc.c
@@ -1577,6 +1577,18 @@ static void alcSetError(ALCdevice *device, ALCenum errorCode)
 }
 
 
+/* UpdateClockBase
+ *
+ * Updates the device's base clock time with however many samples have been
+ * done. This is used so frequency changes on the device don't cause the time
+ * to jump forward or back.
+ */
+static inline void UpdateClockBase(ALCdevice *device)
+{
+    device->ClockBase += device->SamplesDone * DEVICE_CLOCK_RES / device->Frequency;
+    device->SamplesDone = 0;
+}
+
 /* UpdateDeviceParams
  *
  * Updates device parameters according to the attribute list (caller is
@@ -1683,6 +1695,8 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
             V0(device->Backend,stop)();
         device->Flags &= ~DEVICE_RUNNING;
 
+        if(freq != device->Frequency)
+            UpdateClockBase(device);
         device->Frequency = freq;
         device->FmtChans = schans;
         device->FmtType = stype;
@@ -1749,6 +1763,8 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
         if((CPUCapFlags&(CPU_CAP_SSE|CPU_CAP_NEON)) != 0)
             device->UpdateSize = (device->UpdateSize+3)&~3;
 
+        if(freq != device->Frequency)
+            UpdateClockBase(device);
         device->Frequency = freq;
         device->NumMonoSources = numMono;
         device->NumStereoSources = numStereo;
@@ -1758,6 +1774,8 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const ALCint *attrList)
     if((device->Flags&DEVICE_RUNNING))
         return ALC_NO_ERROR;
 
+    UpdateClockBase(device);
+
     oldFreq  = device->Frequency;
     oldChans = device->FmtChans;
     oldType  = device->FmtType;
@@ -2935,6 +2953,9 @@ ALC_API ALCdevice* ALC_APIENTRY alcOpenDevice(const ALCchar *deviceName)
 
     device->ContextList = NULL;
 
+    device->ClockBase = 0;
+    device->SamplesDone = 0;
+
     device->MaxNoOfSources = 256;
     device->AuxiliaryEffectSlotMax = 4;
     device->NumAuxSends = MAX_SENDS;
@@ -3402,6 +3423,9 @@ ALC_API ALCdevice* ALC_APIENTRY alcLoopbackOpenDeviceSOFT(const ALCchar *deviceN
 
     device->ContextList = NULL;
 
+    device->ClockBase = 0;
+    device->SamplesDone = 0;
+
     device->MaxNoOfSources = 256;
     device->AuxiliaryEffectSlotMax = 4;
     device->NumAuxSends = MAX_SENDS;
diff --git a/Alc/ALu.c b/Alc/ALu.c
index bf09450f..bf3d8174 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -1126,6 +1126,14 @@ ALvoid aluMixData(ALCdevice *device, ALvoid *buffer, ALsizei size)
             for(i = 0;i < SamplesToDo;i++)
                 (*slot)->WetBuffer[0][i] = 0.0f;
         }
+
+        /* Increment the clock time. Every second's worth of samples is
+         * converted and added to clock base so that large sample counts don't
+         * overflow during conversion. This also guarantees an exact, stable
+         * conversion. */
+        device->SamplesDone += SamplesToDo;
+        device->ClockBase += (device->SamplesDone/device->Frequency) * DEVICE_CLOCK_RES;
+        device->SamplesDone %= device->Frequency;
         ALCdevice_Unlock(device);
 
         /* Click-removal. Could do better; this only really handles immediate
diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index b6a9f0ae..63c996e5 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -623,6 +623,9 @@ struct ALCdevice_struct
     ALfloat SpeakerAngle[MaxChannels];
     ALuint  NumChan;
 
+    ALuint64 ClockBase;
+    ALuint SamplesDone;
+
     /* Temp storage used for mixing. +1 for the predictive sample. */
     ALIGN(16) ALfloat SampleData1[BUFFERSIZE+1];
     ALIGN(16) ALfloat SampleData2[BUFFERSIZE+1];
@@ -669,6 +672,10 @@ struct ALCdevice_struct
 #define INVALID_OFFSET                           (~0u)
 
 
+/* Nanosecond resolution for the device clock time. */
+#define DEVICE_CLOCK_RES  U64(1000000000)
+
+
 /* Must be less than 15 characters (16 including terminating null) for
  * compatibility with pthread_setname_np limitations. */
 #define MIXER_THREAD_NAME "alsoft-mixer"