Unable to record opus on iPadOS 26

[krille-chan]

Package version

Environment

• OS: iPadOS 26 (probably also iOS 26)

Describe the bug

In my app I check audioRecorder.isEncoderSupported if opus is supported and then use opus. This has worked for a long time. However since iOS 26 isEncoderSupported returns true but recording with opus fails with this exception:

PlatformException(record, Failed to start recording, Format conversion isn’t possible. Format or configuration is not supported., null)
#0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:653:7)
message_codecs.dart:653
#1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:367:18)
platform_channel.dart:367
<asynchronous suspension>
#2      AudioRecorder.start.<anonymous closure> (package:record/src/record.dart:66:9)
record.dart:66
<asynchronous suspension>
#3      AudioRecorder._safeCall (package:record/src/record.dart:300:14)
record.dart:300
<asynchronous suspension>
#4      AudioRecorder.start (package:record/src/record.dart:62:5)
record.dart:62
<asynchronous suspension>
#5      RecordingViewModelState.startRecording (package:fluffychat/pages/chat/recording_view_model.dart:94:7)
recording_view_model.dart:94
<asynchronous suspension>

RecordingConfig

await audioRecorder.isEncoderSupported(AudioEncoder.opus); // returns `true`
 RecordConfig(
          encoder: AudioEncoder.opus,
        ),

Tried with record 6.1.2 (latest) also with 6.0.0 (which has worked before on the iOS version before Liquid (gl)ass. As a workaround I now record with aacLc, which works but has compatibility issues with some android apps.

To Reproduce

Steps to reproduce the behavior:

1. Use macOS Tahoe with XCode 26 to build for iPadOS 26
2. Set audio
3. Scroll down to '....'
4. See error

Expected behavior

Recording works without an exception.

[llfbandit]

If, like stated, you really let the default values, you should try with sampleRate 48000, 24000 or 16000.

[talklittle]

On both iOS 26.1 simulator and iOS 18.5 simulator, I was able to reproduce the error while running the example by setting in audio_recorder.dart:

RecordConfig(encoder: AudioEncoder.opus, numChannels: 1);

Fixed by setting sampleRate: 48000. Apparently Opus supports: [8000, 12000, 16000, 24000, 48000].

---

Also had to remember to change the file extension to .ogg or .opus instead of .m4a in audio_recorder_io.dart of the example; otherwise it led to another error:

PlatformException(record, The operation couldn’t be completed. (OSStatus error 1718449215.), null, null)

That is kAudioFormatUnsupportedDataFormatError according to https://stackoverflow.com/questions/4259078/osstatus-error-1718449215

---

I didn't see a good place to enforce known good configurations, for a pull request; maybe it's out of scope for this library?

[llfbandit]

There's already a best effort code to align wrong setups, only if "available"...

record/record_ios/ios/record_ios/Sources/record_ios/extension/RecorderFormatExtension.swift

Lines 139 to 151 in ad5b76d

	if let sampleRate = settings[AVSampleRateKey] as? NSNumber,
	let sampleRates = converter.availableEncodeSampleRates {
	settings[AVSampleRateKey] = nearestValue(values: sampleRates, value: sampleRate, key: "sample rates").floatValue
	} else if !keepSampleRate {
	settings.removeValue(forKey: AVSampleRateKey)
	}
	if let bitRate = settings[AVEncoderBitRateKey] as? NSNumber,
	let bitRates = converter.availableEncodeBitRates {
	settings[AVEncoderBitRateKey] = nearestValue(values: bitRates, value: bitRate, key: "bit rates").intValue
	} else {
	settings.removeValue(forKey: AVEncoderBitRateKey)
	}

Warning, Opus format on Apple platform is wrapped in CAF container. This means that your file will be playable only on iOS platforms by default.