m4a files are not playing back on iOS

[ushan]

It seems NetStream doesn't play back local audio files recorded by ANE using the default AudioRecorderOptions.
Generally speaking, it's not an ANE issue, because the file is recording fine, but I can not find a way to play back the same file just recorded with ANE. So maybe the file can playback with a combination of codec and format defined in AudioRecorderOptions other than in the example but I still was not able to find working one.

Expected behaviour

Expected that the code from the example with playing back m4a with NetStream working and is playing back m4a files

private function audioRecorder_completeHandler( event:AudioRecorderEvent ):void
{
	var file:File = File.applicationStorageDirectory.resolvePath("recording.m4a");
	
	if (_nc == null)
	{
		_nc = new NetConnection();
		_nc.connect(null);
	}
	_ns = new NetStream( _nc );
	_ns.client = new Object();
	_ns.play( "file://"+file.nativePath );
}

Actual behaviour

It is playing back on Emulator but is not playing back on IPhone and IOS Simulator (I extracted recording.m4a recorded with ANE from iOS Simulator and put it in assets for isolating the problem)
On iOS Simulator and iPhone nothing happens after _ns.play( "file://"+file.nativePath );
Any error handlers or StremError
I've tried to run this code after NetConnection status ("NetConnection.Connect.Success")
The same, nothing happens on iOS
I've checked the value of file variable and checked the folder in ApplicationStorage (through MacOS on Simulator).
The playing file exists in the location stored in file variable.
I also tried to use
_ns.play( file.url ); instead of _ns.play( "file://"+file.nativePath );
Tried to set relative path _ns.play( "assets/recording.m4a");
Tried to playback other formats, like "mp3", "flv" etc. The same, is playing back on Emulator but not in iOS

Environment

• AIR SDK version: Harman Air Flex 4.16_ Air 50.2.3.2
• Device OS: iPhone iOS 16.6, Simulator iOS 15
• Device version: iPhone 11
• Development IDE: intelijIdea 2021.2.1
• Development OS: MacOS 12.0.1

Logs

Device logs if relevant

Logs

UPDATE:
I was able to playback only one FLV file encoded in the following format and codec. (not recorded with ANE)
the output of ffprobe:
Stream #0:0: Video: flv1, yuv420p, 320x240, 347 kb/s, 25 fps, 25 tbr, 1k tbn
Stream #0:1: Audio: mp3, 22050 Hz, mono, fltp, 64 kb/s
But there is no such combination of codec and format in supported recording options:

                 var options:AudioRecorderOptions = new AudioRecorderOptions();
                 options.outputFormat =  ...
                 options.audioEncoding = ...;
                 AudioRecorder.service.start( options );

Format: MPEG-4, Codec: AAC:
Format: THREE_GPP, Codec: AMR_NB:
Format: MPEG-4, Codec: AAC_ELD:
Format: THREE_GPP, Codec: AMR_WB:
Format: WEBM, Codec: VORBIS:

But any of them is not playing back, only the mentioned one

[marchbold]

Thanks for reporting this, I'll have to have a look as to what has changed and see if we can identify the issue.

Have you tried any other versions of AIR?

[ushan]

Thank you for the reply, Michael! Yes, I've tried also SDK Flex 4.16.1 Air 33.1.1.686
The same behavior

I've also tried to compile the app on another Mac on an Intell processor (not Apple Silicon) - the same result

[marchbold]

Interesting, sounds like something must have changed on the native side then. What about an older version of iOS, any luck there?

[ushan]

Besides iOS15.0 and 16.6 I tried also other iOS versions, so in total:
iOS I6.6 - the described behavior
iOS 15.0 - the same
iOS 14.1 - the same
iOS 13.1 - the app crashes with the output "Player session terminated"
iOS 12.4 - the app is freezing during recording (the same happens for other versions when I pass to AudioRecorderOptions incompatible combinations of codec and format or a wrong param)

I tried to implement an outdated solution from stack overflow (I'm not sure if it can be connected with the issue in someway)
https://stackoverflow.com/questions/25837321/playing-aac-streams-with-adobe-air-in-android-ios
But it seems the transcoder mentioned in the solution doesn't contain some required classes https://code.google.com/archive/p/project-thunder-snow/
com.thebitstream.*
(on that link from Google source I found only a few classes from com.thebitstream.* but not the used Transcoder

Just in case I tried also to use the following trick, but with no success

private var nc:NetConnection;
private var ns:NetStream;

private function button_clickHandler(event:Event):void
{
    nc = new NetConnection();
    nc.connect(null);
    ns = new NetStream(nc);
    ns.client = { };
    ns.play(null);

    http_stream = new URLStream();
    http_stream.addEventListener(ProgressEvent.PROGRESS, progressHandler)
    var file:File = File.applicationStorageDirectory.resolvePath("recording.m4a");
    http_stream.load(new URLRequest("file://" + file.nativePath))

}


private function progressHandler(e:ProgressEvent):void {
    var b:ByteArray = new ByteArray()
    http_stream.readBytes(b, 0, http_stream.bytesAvailable)
    ns.appendBytes(b)
}