AudioOut stop() & enqueue AudioOut.Flush both lockup Sim and device

[zgramana]

Trying to cancel enqueued samples, and calling either stop or enqueue(stream, AudioOut.Flush) results in a hung device (moddable 2) or simulator (macOS).

[phoddie]

@zgramana, if you would provide an example, that would ensure we are looking into the same issue and help us to isolate the problem. Thanks.

[zgramana]

@phoddie I've sent your PR #265, which both reproduces the problem and provides a needed example for the use of AudioOut (which is woefully under-documented given its rather impressive capabilities--especially as a mixer and for sound+event/effect synchronization).

It appears there are a couple of issues which this example can reproduce. I will file separate issues for them in case they are not the same root cause.

[zgramana]

Steps to reproduce this issue

1. Launch Adds AudioOut version of the piu/Sound example #265 in a debug session targeting the simulator
2. Establish expected behavior:
   1. Press play
   2. Wait for melody to finish playing
   3. Observe the following trace log message: => Playing sound...done
3. Observe the defect
   1. Press play
   2. Immediately press play again
   3. Observe the following trace log message: => Playing sound=> Stopping sound playback!
   4. Notice that no further interaction with the simulator is possible
   5. Notice that the debugger is unresponsive to the 'Kill' command in xsbug

Note: You must force-quit the simulator to tear down the test setup

[phoddie]

@zgramana - nice example. And, yes, it hangs. :(

The fix seems straightforward. I tested on macOS. It should work everywhere. Would you give it a try? In audioOut.c in the function xs_audioout_enqueue move lines 648 to 652 to directly after the unlock in lines 654 - 662. Please let me know how that goes.

We'd be happy to accept the PR. You'll just need to complete the CLA.

[zgramana]

@phoddie The fix works when tested on a Moddable Two and a Mac via the Simulator. Cheers!

• Do you want the change to audioOut.c added to the PR?
• Where does the CLA PDF go once signed?

[phoddie]

Thanks for confirming. I committed the change already so it is in the current tree.

You can email the executed CLA PDF to info@moddable.com. Thank you!

[zgramana]

• Email signed CLA