Some good news! After another hectic night and morning of trying to trace this bug, including setting all audio to the same bitrate which didn't help, I found the cause:

It seems positioned audio is to blame. I had the thought, then googled to see if anything came up, and found this C3 bug report.

It seems SnipG was right about how serious the bug is and I share their frustrations, while it might not be something that is evident on PC, on iOS it's hugely amplified. It's especially frustrating that they created a perfect reproduction of the bug which can be accessed from the browser, and yet it was not taken seriously. If it had been, whether through a disclaimer on the Scirra site, or in the positioned audio description in C3, or even by removing it altogether, then I'd have been aware of this much earlier.

It's worth noting there are some new abnormalities, like looped sound effects continuing into the next scene, but that's easily fixed by stopping at the end of a scene.

I'd imagine that this will be affecting all projects using positioned audio, with different degrees of severity depending on how often the sounds are played.

I'm afraid no such relationship exists at all. I'd love to have such a close relationship with Apple. But they are an incredibly opaque company who rarely seem to talk to anyone on the outside at all.

I appreciate that this is generally the case with apple and they are not forthcoming at all.

It's not yet clear that is actually the case. If only games that are 5 years old are broken, it's possible it was something we already fixed a long time ago, and thus the impact should be pretty limited. If all games are affected, we could potentially have a big problem, but even then what can we do? We can't fix iOS, only Apple can. It's often extremely difficult to find workarounds as we have to rely on sheer guesswork. If you can reproduce the problem in a new Construct 3 project, that would signify a wider problem. If you then share that project I could try testing this further myself, but once again, I can't guarantee that anything can be done until Apple fix the problem.

I should reiterate this is happening in the new version which is built in Construct 3, using the C3 runtime. It's worse in the C3 version, as while the C2 version has serious lag when a sound effect is played (and that layer staying visible problem), the C3 version's audio quickly deteriorates to white noise.

FWIW I just tried exporting Space Blaster to iOS and running it via Xcode on an iPhone with iOS 14.6. Audio playback worked just fine. So there doesn't seem to be any kind of fundamental issue with audio playback on iOS 14.6, at least as far as I can tell from that test. Xcode did log a message about "Required client entitlement is missing", but it did not seem to affect anything, and all audio playback worked fine regardless. Frankly I don't know what that message means or why it would appear, but it doesn't seem to cause any problem in my test.

I can't imagine space blaster would show any noticeable effect from this bug. My game is abound 3 hours long, and the audio breaks down completely in the second scene, about 8 mins into gameplay. A song is playing, while two sound effects (a horse trotting, and a wheel turning) are playing on loop throughout. The sound completely breaks down about 20 secs into this scene. I imagine this is due to the error being thrown every time the two sound effects, which are a couple of seconds long, loop.

I’m having a huge problem with audio in iOS 14.5.1 and 14.6 which is making both the current app store version of my game built in 2016, and the new version I’ve been building to replace this unplayable. In the console on Xcode, this is the error I receive whenever any audio plays:

[ProcessSuspension] 0x101cdf060 - ProcessAssertion: Failed to acquire RBS MediaPlayback assertion 'WebKit Media Playback' for process with PID 1126, error: Error Domain=RBSAssertionErrorDomain Code=3 "Required client entitlement is missing" UserInfo={RBSAssertionAttribute=<RBSDomainAttribute| domain:"com.apple.webkit" name:"MediaPlayback" sourceEnvironment:"(null)">, NSLocalizedFailureReason=Required client entitlement is missing}

The important clues seem to be 'WebKit Media Playback' , "Required client entitlement is missing", "com.apple.webkit" and :"MediaPlayback"

The audio still plays but crackles with every sound effect, then half way through the second scene as a song is playing the sound deteriorates completely, crackling more and more until it is pure white noise. When I exit back to the main menu, and start a new game, or even click the options which plays a small sound effect, the sound is still crackling, and has not reset itself after getting progressively worse as the errors piled up.

The current App store version of my game built in 2016 still works perfectly on iOS 12.5.1 on my iPad mini, and so does the new version I’m testing.

iOS 14.5.1 and 14.6 also create audio bugs on the 2016 version: whenever a sound plays the game lags big time – I imagine because of the entitlement error. The 2016 version also displays some strange behaviour in the second scene of my game, whereby a “Touch to Start” screen (I put at the start of each scene back when iOS needed a touch input to start audio) stays on the screen after you touch, making the entire scene play out beneath a black layer. This is how I became aware that anything was even wrong – a customer emailed me to tell me they were stuck at this point, and sure enough the same thing happened to me. I can tell the scene is playing out as the music and sounds play out once you touch, and after a couple of minutes, the next scene starts.

This is obviously a new thing as people have been playing this build for 5 years and this is the first time it’s been reported, and any google search to do with this error on other engines that use webkit date only from last year. I've seen reports of it in both the apple developer forums and webkit bug reports. I've tried creating a new project with just a button that plays a sound, and the error still appears.

Here's everything I've tried

• Building the old Construct 2 project with the C3 export manager
• Building with C3 and C2 runtime
• Using only .m4a audio
• Using only .mp3 audio
• Using only .webmd audio
• Adding entitlements/capabilities that seem like they might include this in both xcode and the provisioning profile
• Preloading/not preloading sound
• Putting music in sounds folder to preload all sounds
• Using/not using worker
• Setting audio to Play in Background
• Searching high and low all over forums where there is any mention of this bug for solutions.
• I purchased an iPod Touch 7th gen so I could test on the latest iOS.
• This occurs on both a physical iPod Touch and Apple simulated devices

So my best guess is that this is a problem with at least iOS 14.5.1 and 14.6 and webkit. I’m guessing that iOS 14 requires this entitlement to play any kind of audio or media, and that this has been affecting projects since it was released. I’m not sure it has anything to do with the new version of Cordova, as my old app still has trouble on the new iOS.

I’ve been working solidly to fix this for 4 days now and am at my wits end, I’m not one to ask for help as you can see by how long it’s taken, but I’m not sure what else to do. My game is currently #78 in Role Playing in the UK and I hate the thought of people trying to play it and being disappointed, so working around the clock to fix it.

Ashley your help would be highly appreciated, I imagine this is affecting all iOS releases.