Store the source's previous samples with the voice

This helps avoid different results when looping is toggled within a couple
samples of the loop point, or when a processed buffer is removed while the
source is only a couple samples into the next buffer.

3 files changed, 17 insertions, 0 deletions

diff --git a/OpenAL32/Include/alSource.h b/OpenAL32/Include/alSource.h
index 89c210b9..34c3575b 100644
--- a/OpenAL32/Include/alSource.h
+++ b/OpenAL32/Include/alSource.h
@@ -35,6 +35,8 @@ typedef struct ALvoice {
 
     ALuint Offset; /* Number of output samples mixed since starting. */
 
+    alignas(16) ALfloat PrevSamples[MAX_INPUT_CHANNELS][MAX_PREVIOUS_SAMPLES];
+
     DirectParams Direct;
     SendParams Send[MAX_SENDS];
 } ALvoice;
diff --git a/OpenAL32/Include/alu.h b/OpenAL32/Include/alu.h
index 051a0f0d..ba7afedb 100644
--- a/OpenAL32/Include/alu.h
+++ b/OpenAL32/Include/alu.h
@@ -32,6 +32,9 @@
 
 #define MAX_PITCH  (255)
 
+/* Maximum number of previous buffer samples needed for resampling. */
+#define MAX_PREVIOUS_SAMPLES 4
+
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/OpenAL32/alSource.c b/OpenAL32/alSource.c
index f5b7111f..f91b3878 100644
--- a/OpenAL32/alSource.c
+++ b/OpenAL32/alSource.c
@@ -2574,6 +2574,7 @@ ALvoid SetSourceState(ALsource *Source, ALCcontext *Context, ALenum state)
     {
         ALCdevice *device = Context->Device;
         ALbufferlistitem *BufferList;
+        ALboolean discontinuity;
         ALvoice *voice = NULL;
         ALsizei i;
 
@@ -2594,13 +2595,20 @@ ALvoid SetSourceState(ALsource *Source, ALCcontext *Context, ALenum state)
             Source->position = 0;
             Source->position_fraction = 0;
             ATOMIC_STORE(&Source->current_buffer, BufferList);
+            discontinuity = AL_TRUE;
         }
         else
+        {
             Source->state = AL_PLAYING;
+            discontinuity = AL_FALSE;
+        }
 
         // Check if an Offset has been set
         if(Source->Offset >= 0.0)
+        {
             ApplyOffset(Source);
+            /* discontinuity = AL_TRUE;??? */
+        }
 
         /* If there's nothing to play, or device is disconnected, go right to
          * stopped */
@@ -2631,6 +2639,10 @@ ALvoid SetSourceState(ALsource *Source, ALCcontext *Context, ALenum state)
             voice->Source = Source;
         }
 
+        /* Clear previous samples if playback is discontinuous. */
+        if(discontinuity)
+            memset(voice->PrevSamples, 0, sizeof(voice->PrevSamples));
+
         voice->Direct.Moving  = AL_FALSE;
         voice->Direct.Counter = 0;
         for(i = 0;i < MAX_INPUT_CHANNELS;i++)