ios - Audio Ducking 后音乐更柔和？

Question

我有一些代码可以在我的应用程序中实现音频闪避。当用户正在听一些音乐时，然后进入某个位置，将播放特定的音乐片段。发生这种情况时，正在播放的原始音乐“低声”(或变得更安静)，而我的应用程序开始播放的新音乐片段开始播放。然而，在该音乐结束播放后，正在播放的原始音乐再次播放，但比之前柔和得多。有想法该怎么解决这个吗？下面是我的代码:

audioPlayer = AVAudioPlayer(data: NSData(contentsOfMappedFile: musicFilePath), error: nil)

//Before music is played, make sure background music is off and audio ducking is turned on
AVAudioSession.sharedInstance().setActive(false, withOptions: AVAudioSessionSetActiveOptions.allZeros, error: nil)
        AVAudioSession.sharedInstance().setCategory("AVAudioSessionCategoryPlayback", withOptions: AVAudioSessionCategoryOptions.DuckOthers, error: nil)

audioPlayer.prepareToPlay()
audioPlayer.play()

//Allows audio player to play in the background & turn back on previously played music.
AVAudioSession.sharedInstance().setCategory("AVAudioSessionCategoryAmbient", withOptions: AVAudioSessionCategoryOptions.allZeros, error: nil)
AVAudioSession.sharedInstance().setActive(true, error: nil) 

我试图查看文档，但没有找到太多。任何帮助，将不胜感激。谢谢!

编辑:根据以下答案进行音频回避时代码的外观:

       audioPlayer = AVAudioPlayer(data: NSData(contentsOfMappedFile: musicFilePath), error: nil)

        AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, withOptions: AVAudioSessionCategoryOptions.allZeros, error: nil)
        AVAudioSession.sharedInstance().setActive(true, error: nil)

        audioPlayer.prepareToPlay()
        audioPlayer.play()

        AVAudioSession.sharedInstance().setActive(false, error: nil)
        AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryAmbient, withOptions: AVAudioSessionCategoryOptions.allZeros, error: nil)
        AVAudioSession.sharedInstance().setActive(true, error: nil)

编辑 2:

audioPlayer = AVAudioPlayer(data: NSData(contentsOfMappedFile: musicFilePath), error: nil)
audioPlayer.delegate = self
AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, withOptions: AVAudioSessionCategoryOptions.allZeros, error: nil)
AVAudioSession.sharedInstance().setActive(true, error: nil)

audioPlayer.prepareToPlay()
audioPlayer.play()

然后在 audioPlayerDidFinishPlaying 方法中，我放置了隐藏音频的代码:

func audioPlayerDidFinishPlaying(player: AVAudioPlayer!, successfully flag: Bool){
    //Prepare to play after Sound finished playing
    AVAudioSession.sharedInstance().setActive(false, error: nil)
    AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryAmbient, withOptions: AVAudioSessionCategoryOptions.allZeros, error: nil)
    AVAudioSession.sharedInstance().setActive(true, error: nil)
}

Answer 1

set audiosession active :YES when read , finish read , set back to NO at didfinish delegate

-(void)createAVSpeech : (NSString*) readString{


    audioSession_ = [AVAudioSession sharedInstance];

    NSError *setCategoryError = nil;

    [audioSession_ setCategory:AVAudioSessionCategoryPlayback
                   withOptions:AVAudioSessionCategoryOptionDuckOthers error:&setCategoryError];

    NSError *activationError = nil;
    [audioSession_ setActive:YES error:&activationError];

    speech_ = [[AVSpeechSynthesizer alloc] init];
    speech_.delegate = self;

    AVSpeechUtterance *utterance = [[AVSpeechUtterance alloc] initWithString:readString];
    NSString *readLang = @"en-US";
    float speedrate = 1;
    utterance.rate = AVSpeechUtteranceDefaultSpeechRate * speedrate;
    utterance.pitchMultiplier =0.8;

    utterance.voice = [AVSpeechSynthesisVoice voiceWithLanguage:readLang];

    [speech_ speakUtterance:utterance];
}


-(void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didFinishSpeechUtterance:(AVSpeechUtterance *)utterance{

    NSLog(@"did finish speech");
        [audioSession_ setActive:NO error:nil];
}