So if you go into System Preferences on a MacBook and toggle between a pair of
connected bluetooth headphones and built-in internal speakers, SDL will
switch the device it is playing sound through, to match this setting, on the
fly.
Likewise if the default output device is a USB thing and is unplugged; as the
default device changes at the system level, SDL will pick this up and carry
on with the new default. This is different from our unplug detection for
specific devices, as in those cases we want to send the app a disconnect
notification, instead of migrating transparently as we now do for default
devices.
Note that this should also work for capture devices; if the device changes,
SDL will start recording from the new default.
Fixes Bugzilla #4851.
This was meant to migrate CoreAudio onto the same SDL_RunAudio() path that
most other audio drivers are on, but it introduced a bug because it doesn't
deal with dropped audio buffers...and fixing that properly just introduces
latency.
I might revisit this later, perhaps by reworking SDL_RunAudio to allow for
this sort of API better, or redesigning the whole subsystem or something, I
don't know. I'm not super-thrilled that this has to exist outside of the usual
codepaths, though.
Fixes Bugzilla #4481.
Jona
The following explains why this bug was happening:
This crash was caused because the audio session was being set as active [session setActive:YES error:&err] when the audio device was actually being CLOSED. Certain cases the audio session being set to active would fail and the method would return right away. Because of the way the error was handled we never removed the SDLInterruptionListener thus leaking it. Later when an interruption was received the THIS_ object would contain a pointer to an already released device causing the crash.
The fix:
When only one device remained open and it was being closed we needed to set the audio session as NOT active and completely ignore the returned error to successfully release the SDLInterruptionListener. I think the user assumed that the open_playback_devices and open_capture_devices would equal 0 when all of them where closed but the truth is that at the end of the closing process that the open devices count is decremented.
The audioqueue thread needs to keep running, and processing the CFRunLoop
until the AudioQueue is disposed of, otherwise CoreAudio will hang waiting for
final data to feed the device.
At least, I think this is how it all works. It definitely fixes the bug here!
Since AudioQueueDispose() calls AudioQueueStop() internally, there's no need
for our thread to handle this, either, which is good because the AudioQueue
would be disposed by this point. So now the AudioQueue is disposed first, and
then our thread is joined, and everything works out okay.
Just in case, we mark the device "paused" before setting everything in motion,
so any further callbacks from CoreAudio will write silence and not fire the
app's audio callback again.
Fixes Bugzilla #3868.
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.
We need more than two buffers to flip between if they are small, or CoreAudio
won't make any sound; apparently it needs X milliseconds of audio queued when
it needs to play more or it drops any queued buffers. We are currently
guessing 50 milliseconds as a minimum, but there's probably a more proper
way to get the minimum time period from the system.
Fixes Bugzilla #3656.
The Apple TV remote is currently exposed as a joystick with its touch surface treated as two axes. Key presses are also generated when its buttons and touch surface are used.
A new hint has been added to help deal with deciding whether to background the app when the remote's menu button is pressed: SDL_HINT_APPLE_TV_CONTROLLER_UI_EVENTS.
AudioQueues are available in Mac OS X 10.5 and later (and iOS 2.0 and later).
Their API is much more clear (and if you don't mind the threading tapdance
to get its own CFRunLoop) much easier to use in general for our purposes.
As an added benefit: they seemlessly deal with format conversion in ways
AudioUnits don't: for example, my MacBook Pro's built-in microphone won't
capture at 8000Hz and the AudioUnit version wouldn't resample to hide this
fact; the AudioQueue version, however, can handle this.
- It's now always called if device->hidden isn't NULL, even if OpenDevice()
failed halfway through. This lets implementation code not have to clean up
itself on every possible failure point; just return an error and SDL will
handle it for you.
- Implementations can assume this->hidden != NULL and not check for it.
- implementations don't have to set this->hidden = NULL when done, because
the caller is always about to free(this).
- Don't reset other fields that are in a block of memory about to be free()'d.
- Implementations all now free things like internal mix buffers last, after
closing devices and such, to guarantee they definitely aren't in use anymore
at the point of deallocation.
