Babylon使用麦克风并处理常见问题解决

目录

• 引言
• 问题1：Property 'constraints' does not exist on type 'Window & typeof globalThis'.
• 问题2： Property 'stream' does not exist on type 'Window & typeof globalThis'.ts(2339)
• 问题3： Property 'oninactive' does not exist on type 'MediaStream'.ts(2339)
• 总结

引言

在Babylon.js中媒体设备流使用起来有很多坑，我们将在本文中逐一说明这些坑并提供相应的解决方案。

问题1：Property 'constraints' does not exist on type 'Window & typeof globalThis'.

在比较新的浏览器中，navigator对象中的getUserMedia方法已经被废弃了。取而代之的是navigator.mediaDevices.getUserMedia()，并且constraints应该作为参数传入。

const constraints = { audio: true, video: false };
navigator.mediaDevices.getUserMedia(constraints)

对于问题 Property 'constraints' does not exist on type 'Window & typeof globalThis'.ts(2339)。这是因为 TypeScript 没有识别到constraints变量的类型，可以尝试直接定义一个 const constraints 常量。

问题2： Property 'stream' does not exist on type 'Window & typeof globalThis'.ts(2339)

如果在使用媒体设备流时，你遇到了“Property 'stream' does not exist on type 'Window & typeof globalThis'.ts(2339)” 这个问题出现在TypeScript项目中。因为该类型Script不认识window.stream, 所以我们需要将它声明为any类型。解决方法如下：

(window as any).stream = stream;

这让编译器知道 window 对象现在具有一个名为stream的属性。

问题3： Property 'oninactive' does not exist on type 'MediaStream'.ts(2339)

在较新版本的Web API中，MediaStream对象不再包含oninactive属性，需要更改事件监听方式。 解决方法如下：

stream.addEventListener('inactive', () => {
    console.log('Stream ended ... ...');
});

而不是

stream.oninactive = () => {
    console.log('Stream ended ... ...');
};

此更改暴露了更多事件，同时也需要更改您的代码来处理它们。

总结

在 Babylon.js 中，使用媒体设备流时出现的问题通常是由于您没有根据最新的约定执行操作，或者由于 TypeScript 编译器不知道您所做的更改而导致的。通过遵循我们提供的指南和解决方案，您应该能够轻松地解决这些问题。

示例源码(修改前)：

loadingASoundFromTheMicrophone = (scene: Scene, canvas: HTMLCanvasElement) => {
        let engine = scene.getEngine();
        let freeCamera = new FreeCamera("freeCamera", new Vector3(0, 5, -10), scene);
        freeCamera.setTarget(Vector3.Zero());
        freeCamera.attachControl(canvas, true);
        let hemisphericLight = new HemisphericLight("hemisphericLight", new Vector3(0, 1, 0), scene);
        hemisphericLight.intensity = 0.7;
        let sphere = MeshBuilder.CreateSphere("sphere", {segments: 16, diameter: 2}, scene);
        const constraints = window.constraints = { audio: true, video: false };
        function handleSuccess(stream: MediaStream) {
            const audioTracks = stream.getAudioTracks();
            console.log('Got stream with constraints:', constraints);
            console.log(`Using audio device: ${audioTracks[0].label}`);
            stream.oninactive = function() {
                console.log('Stream ended');
            };
            window.stream = stream; // make variable available to browser console
            var bjsSound = new Sound("mic", stream, scene);
            bjsSound.attachToMesh(sphere);
            bjsSound.play();
        }
        function handleError(error: any) {
            console.log('navigator.getUserMedia error: ', error);
        }
        navigator.mediaDevices.getUserMedia(constraints).then(handleSuccess).catch(handleError);
        return scene;
    }

示例源码(修改后)：

loadingASoundFromTheMicrophone = (scene: Scene, canvas: HTMLCanvasElement) => {
        let engine = scene.getEngine();
        let freeCamera = new FreeCamera("freeCamera", new Vector3(0, 5, -10), scene);
        freeCamera.setTarget(Vector3.Zero());
        freeCamera.attachControl(canvas, true);
        let hemisphericLight = new HemisphericLight("hemisphericLight", new Vector3(0, 1, 0), scene);
        hemisphericLight.intensity = 0.7;
        let sphere = MeshBuilder.CreateSphere("sphere", {segments: 16, diameter: 2}, scene);
        const constraints = {  audio: true, video: false };
        function handleSuccess(stream: MediaStream) {
            const audioTracks = stream.getAudioTracks();
            console.log('Got stream with constraints:', constraints);
            console.log(`Using audio device: ${audioTracks[0].label}`);
            stream.addEventListener('inactive', () => {
                console.log('Stream ended ... ...');
            });
            (window as any).stream = stream; // make variable available to browser console
            var bjsSound = new Sound("mic", stream, scene);
            bjsSound.attachToMesh(sphere);
            bjsSound.play();
        }
        function handleError(error: any) {
            console.log('navigator.getUserMedia error: ', error);
        }
        navigator.mediaDevices.getUserMedia(constraints).then(handleSuccess).catch(handleError);
        return scene;
    }

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