实时改变AVSpeechUtterance速率

Question

我目前正在开发一个iOS应用程序，它使用AVSynthesizer将文本转换为语音。

我想要做的是，当合成器说话时，说话率可以改变，用滑块和说话速度可以改变。

我在滑块的IBAction中这样做: self.utterance = sender.value

但是合成器不会改变速度。我一直在找资料，但还没找到什么。我是做什么的？提前谢谢。

Answer 1

好的，在玩了一些我不知道的酷功能之后，我找到了一种改变语速的方法。主要的问题是，目前的话语是由合成人排队，rate不能改变。对应于文件：

/* Setting these values after a speech utterance has been enqueued will have no effect. */

open var rate: Float // Values are pinned between AVSpeechUtteranceMinimumSpeechRate and AVSpeechUtteranceMaximumSpeechRate.

open var pitchMultiplier: Float // [0.5 - 2] Default = 1

open var volume: Float // [0-1] Default = 1

因此，解决办法是停止合成器，用修剪好的弦给他新的话语。

import UIKit
import AVFoundation

class ViewController: UIViewController {
    var synthesizer: AVSpeechSynthesizer!
    var string: String!
    var currentRange: NSRange = NSRange(location: 0, length: 0)

    @IBAction func sl(_ sender: UISlider) {
        synthesizer.stopSpeaking(at: .immediate)

        if currentRange.length > 0 {
            let startIndex = string.index(string.startIndex, offsetBy: NSMaxRange(currentRange))
            let newString = string.substring(from: startIndex)
            string = newString
            synthesizer.speak(buildUtterance(for: sender.value, with: string))
        }
    }

    func buildUtterance(for rate: Float, with str: String) -> AVSpeechUtterance {
        let utterance = AVSpeechUtterance(string: str)
        utterance.rate = rate
        utterance.voice = AVSpeechSynthesisVoice(language: "en-US")
        return utterance
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        string = "I am currently developing an iOS app that converts text to speech using AVSynthesizer.What I want to do is that while the synthesizer is speaking, utterance rate can be changed and with a slider and the speed of the speaking changes. I am doing this in the IBAction of the slider: self.utterance = sender.value but the synthesizer doesn't change the speed. Ive been looking for information but I haven't found something yet. What can I do? Thanks in advance."

        synthesizer = AVSpeechSynthesizer()
        synthesizer.delegate = self
        synthesizer.speak(buildUtterance(for: AVSpeechUtteranceDefaultSpeechRate, with: string))
    }
}

extension ViewController: AVSpeechSynthesizerDelegate {
    func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, willSpeakRangeOfSpeechString characterRange: NSRange, utterance: AVSpeechUtterance) {
        debugPrint(characterRange.toRange())
        currentRange = characterRange
    }
}

1. 实现AVSpeechSynthesizerDelegate的委托方法AVSpeechSynthesizerDelegate，并将合成器的委托定义为self：synthesizer.delegate = self
2. 在该委托方法中，保存接下来要讲的characterRange。
3. 将IBAction func sl(_ sender: UISlider)绑定到滑块的事件touchUpInside。
4. 在该IBAction中，停止说话，并从索引中获取当前文本的子字符串，它将继续。
5. 建立新的话语并开始说出来
6. 利润。

Answer 2

swift 3

import UIKit
import AVFoundation     

class ViewController: UIViewController{

    @IBOutlet weak var sliderVolume: UISlider!  //for volume
    @IBOutlet weak var sliderRate: UISlider!    //for rate
    @IBOutlet weak var sliderPitch: UISlider!   //for pitch
    @IBOutlet weak var txtForSpeak: UITextField!

    let speechSynth = AVSpeechSynthesizer()

    @IBAction func btnStartToSpeak(_ sender: UIButton) {

        let speechUtt = AVSpeechUtterance(string: self.txtForSpeak.text!)

            speechUtt.rate = self.sliderRate.value

            speechUtt.volume = self.sliderVolume.value

            speechUtt.pitchMultiplier = self.sliderPitch.value

        self.speechSynth.speak(speechUtt)
    }
}