配置另一个AVAudioSession后，AVCaptureSession失败

Question

我尝试实现录音和录像功能。对于音频，请使用 AVAudioRecorder ，对于视频，请使用AVFoundation（AVCaptureSession + AVAssetWriter）。

这是我的音频设置

AVAudioSession *session = [AVAudioSession sharedInstance];
[session setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker error:&error];
[session setActive:YES error:&error];

NSMutableDictionary *recordSetting = [[NSMutableDictionary alloc] init];
[recordSetting setValue:[NSNumber numberWithInt:kAudioFormatMPEG4AAC]  forKey:AVFormatIDKey];
[recordSetting setValue:[NSNumber numberWithInt:AVAudioQualityMedium]  forKey:AVEncoderAudioQualityKey];
[recordSetting setValue:[NSNumber numberWithFloat:16000.0]             forKey:AVSampleRateKey];
[recordSetting setValue:[NSNumber numberWithInt:1]                     forKey:AVNumberOfChannelsKey];

self.recorder = [[AVAudioRecorder alloc] initWithURL:outputFileURL settings:recordSetting error:&error];
self.recorder.delegate = self;
self.recorder.meteringEnabled = NO;
[self.recorder prepareToRecord];

这是我的catpure会话设置

NSError *error = nil;
_captureSession = [[AVCaptureSession alloc] init];
_captureSession.usesApplicationAudioSession = NO;

_captureDeviceAudio = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
_captureDeviceInputAudio = [AVCaptureDeviceInput deviceInputWithDevice:_captureDeviceAudio error:&error];

// capture device ouputs
_captureOutputAudio = [[AVCaptureAudioDataOutput alloc] init];
_captureOutputVideo = [[AVCaptureVideoDataOutput alloc] init];

[_captureOutputAudio setSampleBufferDelegate:self queue:_captureCaptureDispatchQueue];
[_captureOutputVideo setSampleBufferDelegate:self queue:_captureCaptureDispatchQueue];

// Skip code here add AVCaptureDeviceInput and audio/video input/output

通过以下方式解决问题。

1. 创建＆amp; init AVCaptureSession，一切正常
2. 创建＆amp;启动录音，一切正常
3. 重用现有的AVCaptureSession，委托方法 captureOutput：didOutputSampleBuffer：fromConnection：不会收到任何音频数据
4. 重新创建＆amp; init AVCaptureSession，修复它（但这不是高性能解决方案）

这对我来说很奇怪。通过设置usesAppicationAudioSession = NO，捕获会话将维护一个私有音频会话，其设置与共享的audioSession分开。如果是这种情况，我在共享的AudioSession（在我的音频设置中）更改的任何内容不应该影响