Fix XAudio2.7 hanging on device disconnection

SDL/audio/xaudio2_7.c

@@ -109,8 +109,27 @@ static unsigned _audio_get_frequency(void)
     return audio_frequency;
 }
 
+static void nop(IXAudio2EngineCallback *this)
+{
+}
+
+static bool _audio_init(void);
+
+static _Atomic bool needs_restart = false;
+
+static void critical_error(IXAudio2EngineCallback *this, HRESULT error)
+{
+    needs_restart = true;
+}
+
+
 static size_t _audio_get_queue_length(void)
 {
+    if (needs_restart) {
+        _audio_init();
+        if (!xaudio2) return 0;
+        _audio_set_paused(!playing);
+    }
     static XAUDIO2_VOICE_STATE state;
     IXAudio2SourceVoice_GetState(source_voice, &state);
     
@@ -120,6 +139,12 @@ static size_t _audio_get_queue_length(void)
 static void _audio_queue_sample(GB_sample_t *sample)
 {
     if (!playing) return;
+    
+    if (needs_restart) {
+        _audio_init();
+        if (!xaudio2) return;
+        _audio_set_paused(!playing);
+    }
         
     static XAUDIO2_BUFFER buffer = {.AudioBytes = sizeof(*sample) * BATCH_SIZE, };
     sample_pool[pos] = *sample;
@@ -133,6 +158,14 @@ static void _audio_queue_sample(GB_sample_t *sample)
 
 static bool _audio_init(void)
 {
+    if (needs_restart) {
+        needs_restart = false;
+        if (xaudio2) {
+            xaudio2->lpVtbl->Release(xaudio2);
+            xaudio2 = NULL;
+        }
+    }
+    
     HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
     if (FAILED(hr)) {
         fprintf(stderr, "CoInitializeEx failed: %lx\n", hr);
@@ -168,6 +201,19 @@ static bool _audio_init(void)
         return false;
     }
     
+    
+    static IXAudio2EngineCallbackVtbl callbacks = {
+        nop,
+        nop,
+        .OnCriticalError = critical_error
+    };
+    
+    static IXAudio2EngineCallback callbackObject = {
+        .lpVtbl = &callbacks
+    };
+    
+    IXAudio2SourceVoice_RegisterForCallbacks(xaudio2, &callbackObject);
+    
     return true;
 }
 

SDL/audio/xaudio2_7.h

@@ -49,6 +49,21 @@ typedef struct IXAudio2 {
 typedef struct IXAudio2Vtbl IXAudio2Vtbl;
 typedef void *IXAudio2MasteringVoice;
 
+#undef INTERFACE
+#define INTERFACE IXAudio2EngineCallback
+DECLARE_INTERFACE(IXAudio2EngineCallback)
+{
+    // Called by XAudio2 just before an audio processing pass begins.
+    STDMETHOD_(void, OnProcessingPassStart) (THIS) PURE;
+    
+    // Called just after an audio processing pass ends.
+    STDMETHOD_(void, OnProcessingPassEnd) (THIS) PURE;
+    
+    // Called in the event of a critical system error which requires XAudio2
+    // to be closed down and restarted.  The error code is given in Error.
+    STDMETHOD_(void, OnCriticalError) (THIS_ HRESULT Error) PURE;
+};
+
 #undef INTERFACE
 #define INTERFACE IXAudio2
 
@@ -61,8 +76,8 @@ struct IXAudio2Vtbl {
     STDMETHOD(Initialize) (THIS_ UINT32 Flags,
                            XAUDIO2_PROCESSOR XAudio2Processor) PURE;
 
-     void *RegisterForCallbacks;
-     void *UnregisterForCallbacks;
+    STDMETHOD(RegisterForCallbacks) (THIS_ __in IXAudio2EngineCallback *pCallback) PURE;
+    void *UnregisterForCallbacks;
     
     STDMETHOD(CreateSourceVoice) (THIS_ __deref_out IXAudio2SourceVoice **ppSourceVoice,
                                   __in const WAVEFORMATEX *pSourceFormat,
@@ -91,6 +106,7 @@ DEFINE_CLSID(XAudio2, 5a508685, a254, 4fba, 9b, 82, 9a, 24, b0, 03, 06, af);
 DEFINE_IID(IXAudio2, 8bcf1f58, 9fe7, 4583, 8a, c6, e2, ad, c4, 65, c8, bb);
 
 
+#define IXAudio2SourceVoice_RegisterForCallbacks(This, pCallback) ((This)->lpVtbl->RegisterForCallbacks(This,pCallback))
 #define IXAudio2SourceVoice_Start(This,Flags,OperationSet) ((This)->lpVtbl->Start(This,Flags,OperationSet))
 #define IXAudio2SourceVoice_Stop(This,Flags,OperationSet) ((This)->lpVtbl->Stop(This,Flags,OperationSet))
 #define IXAudio2SourceVoice_SubmitSourceBuffer(This,pBuffer,pBufferWMA) ((This)->lpVtbl->SubmitSourceBuffer(This,pBuffer,pBufferWMA))