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POCan not restart an interrupted audio input queue in background mode on iOS
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copied!<p>I'm writing an iOS App using an AudioQueue for recording. I create an input queue configured to get linear PCM, stated this queue and everything works as expected.</p> <p>To manage interruptions, I implemented the delegate methods of AVAudioSession to catch the begin and the end of an interruption. The method endInterruption looks like the following:</p> <pre><code>- (void)endInterruptionWithFlags:(NSUInteger)flags; { if (flags == AVAudioSessionInterruptionFlags_ShouldResume && audioQueue != 0) { NSLog(@"Current audio session - category: '%@' mode: '%@'", [[AVAudioSession sharedInstance] category], [[AVAudioSession sharedInstance] mode]); NSError *error = nil; OSStatus errorStatus; if ((errorStatus = AudioSessionSetActive(true)) != noErr) { error = [self errorForAudioSessionServiceWithOSStatus:errorStatus]; NSLog(@"Could not reactivate the audio session: %@", [error localizedDescription]); } else { if ((errorStatus = AudioQueueStart(audioQueue, NULL)) != noErr) { error = [self errorForAudioQueueServiceWithOSStatus:errorStatus]; NSLog(@"Could not restart the audio queue: %@", [error localizedDescription]); } } } // ... } </code></pre> <p>If the app gets interrupted while it is in foreground, everything works correct. The problem appears, if the interruption happens in the background. Activating the audio session result in the error <strong>!cat</strong>:</p> <blockquote> <p>The specified audio session category cannot be used for the attempted audio operation. For example, you attempted to play or record audio with the audio session category set to kAudioSessionCategory_AudioProcessing.</p> </blockquote> <p>Starting the queue without activating the session results in the error code: <strong>-12985</strong></p> <p>At that point the category is set to <strong>AVAudioSessionCategoryPlayAndRecord</strong> and the mode is <strong>AVAudioSessionModeDefault</strong>.</p> <p>I couldn't find any documentation for this error message, nor if it is possible to restart an input audio queue in the background.</p>

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