Ensure voices has been updated once before mixing them

Sometimes the mixer is temporarily prevented from applying updates, when
multiple sources need to be updated simultaneously for example, but does not
prevent mixing. If the mixer runs during that time and a voice was just
started, it would've mixed the voice without any internal properties being set
for it.

2 files changed, 10 insertions, 2 deletions

diff --git a/Alc/ALu.c b/Alc/ALu.c
index 3ba068a2..77852805 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -1460,8 +1460,9 @@ ALvoid aluMixData(ALCdevice *device, ALvoid *buffer, ALsizei size)
             voice_end = voice + ctx->VoiceCount;
             for(;voice != voice_end;++voice)
             {
+                ALboolean IsVoiceInit = (voice->Step > 0);
                 source = voice->Source;
-                if(source && source->state == AL_PLAYING)
+                if(source && source->state == AL_PLAYING && IsVoiceInit)
                     MixSource(voice, source, device, SamplesToDo);
             }
 
diff --git a/OpenAL32/alSource.c b/OpenAL32/alSource.c
index 5cc6c34b..e79f0fc3 100644
--- a/OpenAL32/alSource.c
+++ b/OpenAL32/alSource.c
@@ -2986,10 +2986,17 @@ ALvoid SetSourceState(ALsource *Source, ALCcontext *Context, ALenum state)
             voice->Source = Source;
         }
 
-        /* Clear previous samples if playback is discontinuous. */
         if(discontinuity)
+        {
+            /* Clear previous samples if playback is discontinuous. */
             memset(voice->PrevSamples, 0, sizeof(voice->PrevSamples));
 
+            /* Clear the stepping value so the mixer knows not to mix this
+             * until the update gets applied.
+             */
+            voice->Step = 0;
+        }
+
         voice->Moving = AL_FALSE;
         for(i = 0;i < MAX_INPUT_CHANNELS;i++)
         {