This is not a public API (at the moment), but we will be needing this for
other internal things soon.
--HG--
extra : rebase_source : a9cc678783f19b02978f9b09f77b6a4ae9759a92
This tends to be a frequent spot where drivers hang, and the waits were
often unreliable in any case.
Instead, our audio thread now alerts the driver that we're done streaming audio
(which currently XAudio2 uses to alert the system not to warn about the
impending underflow) and then SDL_Delay()'s for a duration that's reasonable
to drain the DMA buffers before closing the device.
This tries to make SDL robust against device drivers that have hung up,
apps don't freeze in catastrophic (but not necessarily uncommon) conditions.
Now we detach the audio thread and let it clean up and don't care if it
never actually runs to completion.
James Zipperer
The problem I was seeing was that the the ALSA hotplug thread would call SDL_RemoveAudioDevice, but my application code was not seeing an SDL_AUDIODEVICEREMOVED event to go along with it. To fix it, I added some code into SDL_RemoveAudioDevice to call SDL_OpenedAudioDeviceDisconnected on the corresponding open audio device. There didn't appear to be a way to cross reference the handle that SDL_RemoveAudioDevice gets and the SDL_AudioDevice pointer that SDL_OpenedAudioDeviceDisconnected needs, so I ended up adding a void *handle field to struct SDL_AudioDevice so that I could do the cross reference.
Is there some other way beside adding a void *handle field to the struct to get the proper information for SDL_OpenedAudioDeviceDisconnected?
- 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.
--HG--
extra : histedit_source : 03a1d12c89ebcc01743777ec68663a227265a7c6%2C722b053ebe4647a9e601d4e2c42e4050366b7f7d
The data produced by the callback is just thrown away and the audio thread
delays as if it's waiting for the hardware to drain.
This lets apps that rely on their audio callback firing regularly continue
to make progress to function as properly as possible in the face of disaster.
Apps that want to know that the device is really gone and deal with that
scenario can use the new hotplug functionality.
Device enumeration now happens at startup and then is managed exclusively
through hotplugging instead of full redetection. The device name list now has
a unique "handle" associated with each item and SDL will pass this to the
backend so they don't have to figure out how a human readable name maps to
real hardware for a second time.
Other cleanups, fixes, improvements, plus all the audio backends updated to
the new interface...largely untested at this point, though.
--HG--
extra : rebase_source : c9a4272788a67deb7a787304ef008188bb40184d
This fills in the core pieces and fully implements it for Mac OS X.
Most other platforms, at the moment, will report a disconnected device if
it fails to write audio, but don't notice if the system's device list changed
at all.
--HG--
extra : rebase_source : f7e7efbbeecfe58338b0f325340c358c2bdfc402
This will (eventually) make SDL_GetQueuedAudioSize() more accurate, and thus
reduce latency. Right now this isn't implemented anywhere, so we assume data
fed to the audio callback is consumed by the hardware and immediately played
to completion.
The thread ID is an unsigned long so it can hold pthread_t so people can do naughty things with it.
I'm going to be adding additional useful thread API functions, but this should prevent crashes in people's existing code on 64-bit architectures.
--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%404327
Audio Ideas - Resampling and Pitch Shifting
by Aaron Wishnick, mentored by Ryan C. Gordon
--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403165
