coreaudio: Better handling of audio buffer queue management.

We don't fill buffers just to throw them away during shutdown now, we let the AudioQueue free its own buffers during disposal (which fixes possible warnings getting printed to stderr by CoreAudio), and we stop the queue after running any queued audio during shutdown, which prevents dropping the end of the audio playback if you opened the device with an enormous sample buffer. Fixes Bugzilla #3555.
libsdl-org · May 24, 2017 · fc4402e · fc4402e
1 parent 126e5a1
commit fc4402e
Showing 1 changed file with 17 additions and 16 deletions.
diff --git a/src/audio/coreaudio/SDL_coreaudio.m b/src/audio/coreaudio/SDL_coreaudio.m
@@ -400,8 +400,12 @@ static BOOL update_audio_session(_THIS, SDL_bool open)
 outputCallback(void *inUserData, AudioQueueRef inAQ, AudioQueueBufferRef inBuffer)
 {
     SDL_AudioDevice *this = (SDL_AudioDevice *) inUserData;
+    if (SDL_AtomicGet(&this->hidden->shutdown)) {
+        return;  /* don't do anything. */
+    }
+
     if (!SDL_AtomicGet(&this->enabled) || SDL_AtomicGet(&this->paused)) {
-        /* Supply silence if audio is enabled and not paused */
+        /* Supply silence if audio is not enabled or paused */
         SDL_memset(inBuffer->mAudioData, this->spec.silence, inBuffer->mAudioDataBytesCapacity);
     } else {
         UInt32 remaining = inBuffer->mAudioDataBytesCapacity;
@@ -430,9 +434,7 @@ static BOOL update_audio_session(_THIS, SDL_bool open)
         }
     }
 
-    if (!SDL_AtomicGet(&this->hidden->shutdown)) {
-        AudioQueueEnqueueBuffer(this->hidden->audioQueue, inBuffer, 0, NULL);
-    }
+    AudioQueueEnqueueBuffer(this->hidden->audioQueue, inBuffer, 0, NULL);
 
     inBuffer->mAudioDataByteSize = inBuffer->mAudioDataBytesCapacity;
 }
@@ -443,7 +445,13 @@ static BOOL update_audio_session(_THIS, SDL_bool open)
               const AudioStreamPacketDescription *inPacketDescs )
 {
     SDL_AudioDevice *this = (SDL_AudioDevice *) inUserData;
-    if (SDL_AtomicGet(&this->enabled) && !SDL_AtomicGet(&this->paused)) {  /* ignore unless we're active. */
+
+    if (SDL_AtomicGet(&this->shutdown)) {
+        return;  /* don't do anything. */
+    }
+
+    /* ignore unless we're active. */
+    if (!SDL_AtomicGet(&this->paused) && SDL_AtomicGet(&this->enabled) && !SDL_AtomicGet(&this->paused)) {
         const Uint8 *ptr = (const Uint8 *) inBuffer->mAudioData;
         UInt32 remaining = inBuffer->mAudioDataByteSize;
         while (remaining > 0) {
@@ -466,9 +474,7 @@ static BOOL update_audio_session(_THIS, SDL_bool open)
         }
     }
 
-    if (!SDL_AtomicGet(&this->hidden->shutdown)) {
-        AudioQueueEnqueueBuffer(this->hidden->audioQueue, inBuffer, 0, NULL);
-    }
+    AudioQueueEnqueueBuffer(this->hidden->audioQueue, inBuffer, 0, NULL);
 }
 
 
@@ -514,7 +520,6 @@ static BOOL update_audio_session(_THIS, SDL_bool open)
 COREAUDIO_CloseDevice(_THIS)
 {
     const SDL_bool iscapture = this->iscapture;
-    int i;
 
 /* !!! FIXME: what does iOS do when a bluetooth audio device vanishes? Headphones unplugged? */
 /* !!! FIXME: (we only do a "default" device on iOS right now...can we do more?) */
@@ -533,19 +538,15 @@ static BOOL update_audio_session(_THIS, SDL_bool open)
     }
 
     if (this->hidden->audioQueue) {
-        for (i = 0; i < this->hidden->numAudioBuffers; i++) {
-            if (this->hidden->audioBuffer[i]) {
-                AudioQueueFreeBuffer(this->hidden->audioQueue, this->hidden->audioBuffer[i]);
-            }
-        }
-        SDL_free(this->hidden->audioBuffer);
         AudioQueueDispose(this->hidden->audioQueue, 1);
     }
 
     if (this->hidden->ready_semaphore) {
         SDL_DestroySemaphore(this->hidden->ready_semaphore);
     }
 
+    /* AudioQueueDispose() frees the actual buffer objects. */
+    SDL_free(this->hidden->audioBuffer);
     SDL_free(this->hidden->thread_error);
     SDL_free(this->hidden->buffer);
     SDL_free(this->hidden);
@@ -718,9 +719,9 @@ static BOOL update_audio_session(_THIS, SDL_bool open)
     if (this->iscapture) {  /* just stop immediately for capture devices. */
         AudioQueueStop(this->hidden->audioQueue, 1);
     } else {  /* Drain off any pending playback. */
-        AudioQueueStop(this->hidden->audioQueue, 0);
         const CFTimeInterval secs = (((this->spec.size / (SDL_AUDIO_BITSIZE(this->spec.format) / 8)) / this->spec.channels) / ((CFTimeInterval) this->spec.freq)) * 2.0;
         CFRunLoopRunInMode(kCFRunLoopDefaultMode, secs, 0);
+        AudioQueueStop(this->hidden->audioQueue, 0);
     }
 
     return 0;