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* audio: don't lock ao_control for pull mode driversKevin Mitchell2020-06-171-2/+7
| | | | | | | | | | | | | The pull mode APIs were previously required to have thread-safe ao_controls. However, locks were added in b83bdd1 for parity with push mode. This introduced deadlocks in ao_wasapi. Instead, only lock ao_control for the push mode APIs. fixes #7787 See also #7832, #7811. We'll wait for feedback to see if those should also be closed.
* audio: fix deadlock on drainingwm42020-06-041-1/+1
| | | | | | | | | | | The playback thread may obviously still fill the AO'S entire audio buffer, which means it unset p->draining, which makes no sense and broke ao_drain(). So just don't unset it here. Not sure if this really fixes this, it was hard to reproduce. Regression due to the recent changes. There are probably many more bugs like this. Stupid asynchronous nightmare state machine. Give me a language that supports formal verification (in presence of concurrency) or something.
* audio: adjust wait durationwm42020-06-031-6/+4
| | | | | | | | | | | | | | | I feel like this makes slightly more sense. At least it doesn't include the potentially arbitrary constant latency that is generally included in the delay value. Also, the buffer status doesn't matter - either we've filled the entire buffer (then we can wait this long), or there's not enough data anyway (then the core will wake up the thread if new data is available). But ultimately, we have to guess, unless the AO does notify us with ao_wakeup_playthread(). Draining may now wait for no reason up to 1/4th of the total buffer time. Shouldn't be a disimprovement in practice.
* audio: avoid possible deadlock regression for some AOswm42020-06-021-2/+17
| | | | | | | | | | | | | | | It's conceivable that ao->driver->reset() will make the audio API wait for ao_read_data() (i.e. its audio callback) to return. Since we recently moved the reset() call inside the same lock that ao_read_data() acquires, this could deadlock. Whether this really happens depends on how exactly the AO behaves. For example, ao_wasapi does not have this problem. "Push" AOs are not affected either. Fix by moving it outside of the lock. Assume ao->driver->start() will not have this problem. Could affect ao_sdl, ao_coreaudio (and similar rotten fruit AOs). I'm unsure whether anyone experienced the problem in practice.
* audio: further simplify internal audio API somewhatwm42020-06-021-20/+12
| | | | | | | | | | | | Instead of the relatively subtle underflow handling, simply signal whether the stream is in a playing state. Should make it more robust. Should affect ao_alsa and ao_pulse only (and ao_openal, but it's broken). For ao_pulse, I'm just guessing. How the hell do you query whether a stream is playing? Who knows. Seems to work, judging from very superficial testing.
* audio: slightly better condition for still_playingwm42020-06-021-1/+1
| | | | | | Just a detail. If wrong (not unlikely because I'm just guessing my own messy state machine), this will make the player freeze due to waiting for something that never happens. Enjoy.
* audio: reduce extra wakeups caused by recent changeswm42020-06-011-5/+4
| | | | | | | | | | | | | | | | The feeder thread basically woke up the core and itself too often, and caused some CPU overhead. This was caused by the recent buffer.c changes. For one, do not let ao_read_data() wake up the core, and instead rely on the feeder thread's own buffer management. This is a bit strange, since the change intended to unify the buffer management, but being more consequent about it is better deferred to later, when the buffer management changes again anyway. And also, the "more" condition in the feeder thread seems outdated, or at least what made it make sense has been destroyed, so do something that may or may not be better. In any case, I'm still not getting underruns with ao_alsa, but the wakeup hammering is gone.
* audio: redo internal AO APIwm42020-06-011-264/+233
| | | | | | | | | | | | | | | | | | | | | | | | | This affects "pull" AOs only: ao_alsa, ao_pulse, ao_openal, ao_pcm, ao_lavc. There are changes to the other AOs too, but that's only about renaming ao_driver.resume to ao_driver.start. ao_openal is broken because I didn't manage to fix it, so it exits with an error message. If you want it, why don't _you_ put effort into it? I see no reason to waste my own precious lifetime over this (I realize the irony). ao_alsa loses the poll() mechanism, but it was mostly broken and didn't really do what it was supposed to. There doesn't seem to be anything in the ALSA API to watch the playback status without polling (unless you want to use raw UNIX signals). No idea if ao_pulse is correct, or whether it's subtly broken now. There is no documentation, so I can't tell what is correct, without reverse engineering the whole project. I recommend using ALSA. This was supposed to be just a simple fix, but somehow it expanded scope like a train wreck. Very high chance of regressions, but probably only for the AOs listed above. The rest you can figure out from reading the diff.
* audio: fix unpausing with some AOswm42020-05-311-1/+1
| | | | | | | | | wasapi/coreaudio/sdl were affected, alsa/pusle were not. The confusion here was that resume() has different meaning with pull and push AOs. Fixes: #7772
* audio: stop applying volume twice for some AOswm42020-05-271-1/+0
| | | | | | | Regression since the recent refactor. How did nobody notice? This happened because the push code now calls the function for the pull code. Both the former and latter apply the volume, so oops.
* audio: remove ao_driver.drainwm42020-05-271-10/+12
| | | | | | | | | | The recent change to the common code removed all calls to ->drain. It's currently emulated via a timed sleep and polling ao_eof_reached(). That is actually fallback code for AOs which lacked draining. I could just readd the drain call, but it was a bad idea anyway. My plan to handle this better is to require the AO to signal a underrun, even if AOPLAY_FINAL_CHUNK is not set. Also reinstate not possibly waiting for ao_lavc.c. ao_pcm.c did not have anything to handle this; whatever.
* audio: merge pull/push ring buffer glue codewm42020-05-251-0/+751
This is preparation to further cleanups (and eventually actual improvements) of the audio output code. AOs are split into two classes: pull and push. Pull AOs let an audio callback of the native audio API read from a ring buffer. Push AOs expose a function that works similar to write(), and for which we start a "feeder" thread. It seems making this split was beneficial, because of the different data flow, and emulating the one or other in the AOs directly would have created code duplication (all the "pull" AOs had their own ring buffer implementation before it was cleaned up). Unfortunately, both types had completely separate implementations (in pull.c and push.c). The idea was that little can be shared anyway. But that's very annoying now, because I want to change the API between AO and player. This commit attempts to merge them. I've moved everything from push.c to pull.c, the trivial entrypoints from ao.c to pull.c, and attempted to reconcile the differences. It's a mess, but at least there's only one ring buffer within the AO code now. Everything should work mostly the same. Pull AOs now always copy the audio data under a lock; before this commit, all ring buffer access was lock-free (except for the decoder wakeup callback, which acquired a mutex). In theory, this is "bad", and people obsessed with lock-free stuff will hate me, but in practice probably won't matter. The planned change will probably remove this copying-under-lock again, but who knows when this will happen. One change for the push AOs now makes it drop audio, where before only a warning was logged. This is only in case of AOs or drivers which exhibit unexpected (and now unsupported) behavior. This is a risky change. Although it's completely trivial conceptually, there are too many special cases. In addition, I barely tested it, and I've messed with it in a half-motivated state over a longer time, barely making any progress, and finishing it under a rush when I already should have been asleep. Most things seem to work, and I made superficial tests with alsa, sdl, and encode mode. This should cover most things, but there are a lot of tricky things that received no coverage. All this text means you should be prepared to roll back to an older commit and report your problem.