Use a separate backend callback to start playback of the device

This allows us to properly update the ALCdevice and its resources with the new
parameters before starting playback, instead of expecting the mixer to block
and wait after it has begun.

This also lets us avoid holding the device lock while resetting and starting
the device, which helps prevent lock inversion on some backends (ie, one thread
locking A then B, and another thread locking B then A), ultimately allowing
certain backends to asynchronously update the ALCdevice without risk of lockup.
Capture still has issues here, however.

1 files changed, 2 insertions, 0 deletions

diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index 2fbea8c3..20f6d656 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -449,6 +449,7 @@ typedef struct {
     ALCenum (*OpenPlayback)(ALCdevice*, const ALCchar*);
     void (*ClosePlayback)(ALCdevice*);
     ALCboolean (*ResetPlayback)(ALCdevice*);
+    ALCboolean (*StartPlayback)(ALCdevice*);
     void (*StopPlayback)(ALCdevice*);
 
     ALCenum (*OpenCapture)(ALCdevice*, const ALCchar*);
@@ -630,6 +631,7 @@ struct ALCdevice_struct
 #define ALCdevice_OpenPlayback(a,b)      ((a)->Funcs->OpenPlayback((a), (b)))
 #define ALCdevice_ClosePlayback(a)       ((a)->Funcs->ClosePlayback((a)))
 #define ALCdevice_ResetPlayback(a)       ((a)->Funcs->ResetPlayback((a)))
+#define ALCdevice_StartPlayback(a)       ((a)->Funcs->StartPlayback((a)))
 #define ALCdevice_StopPlayback(a)        ((a)->Funcs->StopPlayback((a)))
 #define ALCdevice_OpenCapture(a,b)       ((a)->Funcs->OpenCapture((a), (b)))
 #define ALCdevice_CloseCapture(a)        ((a)->Funcs->CloseCapture((a)))