我有一些UTF-8编码的数据生活在Javascript Uint8Array元素的范围内。是否有一种有效的方法来解码这些到一个常规的javascript字符串(我相信javascript使用16位Unicode)?我不想一次添加一个字符，因为字符串连接会变得CPU密集。
当前回答
对于香草，浏览器端，从麦克风录音，base64函数为我工作(我必须实现一个音频发送功能到聊天)。
const ui8a = new Uint8Array(e.target.result);
const string = btoa(ui8a);
const ui8a_2 = atob(string).split(',');
现在是完整代码。感谢Bryan Jennings & breakspirit@py4u.net提供的代码。
https://medium.com/@bryanjenningz/how-to-record-and-play-audio-in-javascript-faa1b2b3e49b
https://www.py4u.net/discuss/282499
index . html
<html>
<head>
<title>Record Audio Test</title>
<meta name="encoding" charset="utf-8" />
</head>
<body>
<h1>Audio Recording Test</h1>
<script src="index.js"></script>
<button id="action" onclick="start()">Start</button>
<button id="stop" onclick="stop()">Stop</button>
<button id="play" onclick="play()">Listen</button>
</body>
</html>
index.js:
const recordAudio = () =>
new Promise(async resolve => {
const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
const mediaRecorder = new MediaRecorder(stream);
const audioChunks = [];
mediaRecorder.addEventListener("dataavailable", event => {
audioChunks.push(event.data);
});
const start = () => mediaRecorder.start();
const stop = () =>
new Promise(resolve => {
mediaRecorder.addEventListener("stop", () => {
const audioBlob = new Blob(audioChunks);
const audioUrl = URL.createObjectURL(audioBlob);
const audio = new Audio(audioUrl);
const play = () => audio.play();
resolve({ audioBlob, audioUrl, play });
});
mediaRecorder.stop();
});
resolve({ start, stop });
});
let recorder = null;
let audio = null;
const sleep = time => new Promise(resolve => setTimeout(resolve, time));
const start = async () => {
recorder = await recordAudio();
recorder.start();
}
const stop = async () => {
audio = await recorder.stop();
read(audio.audioUrl);
}
const play = ()=> {
audio.play();
}
const read = (blobUrl)=> {
var xhr = new XMLHttpRequest;
xhr.responseType = 'blob';
xhr.onload = function() {
var recoveredBlob = xhr.response;
const reader = new FileReader();
// This fires after the blob has been read/loaded.
reader.addEventListener('loadend', (e) => {
const ui8a = new Uint8Array(e.target.result);
const string = btoa(ui8a);
const ui8a_2 = atob(string).split(',');
playByteArray(ui8a_2);
});
// Start reading the blob as text.
reader.readAsArrayBuffer(recoveredBlob);
};
// get the blob through blob url
xhr.open('GET', blobUrl);
xhr.send();
}
window.onload = init;
var context; // Audio context
var buf; // Audio buffer
function init() {
if (!window.AudioContext) {
if (!window.webkitAudioContext) {
alert("Your browser does not support any AudioContext and cannot play back this audio.");
return;
}
window.AudioContext = window.webkitAudioContext;
}
context = new AudioContext();
}
function playByteArray(byteArray) {
var arrayBuffer = new ArrayBuffer(byteArray.length);
var bufferView = new Uint8Array(arrayBuffer);
for (i = 0; i < byteArray.length; i++) {
bufferView[i] = byteArray[i];
}
context.decodeAudioData(arrayBuffer, function(buffer) {
buf = buffer;
play2();
});
}
// Play the loaded file
function play2() {
// Create a source node from the buffer
var source = context.createBufferSource();
source.buffer = buf;
// Connect to the final output node (the speakers)
source.connect(context.destination);
// Play immediately
source.start(0);
}
其他回答
我正在使用这个Typescript代码片段:
function UInt8ArrayToString(uInt8Array: Uint8Array): string
{
var s: string = "[";
for(var i: number = 0; i < uInt8Array.byteLength; i++)
{
if( i > 0 )
s += ", ";
s += uInt8Array[i];
}
s += "]";
return s;
}
如果需要JavaScript版本，则删除类型注释。 希望这能有所帮助!
做什么@Sudhir说，然后得到一个字符串，逗号分隔的数字列表使用:
for (var i=0; i<unitArr.byteLength; i++) {
myString += String.fromCharCode(unitArr[i])
}
这会给你想要的字符串， 如果还相关的话
试试这些函数，
var JsonToArray = function(json)
{
var str = JSON.stringify(json, null, 0);
var ret = new Uint8Array(str.length);
for (var i = 0; i < str.length; i++) {
ret[i] = str.charCodeAt(i);
}
return ret
};
var binArrayToJson = function(binArray)
{
var str = "";
for (var i = 0; i < binArray.length; i++) {
str += String.fromCharCode(parseInt(binArray[i]));
}
return JSON.parse(str)
}
来源:https://gist.github.com/tomfa/706d10fed78c497731ac，向Tomfa致敬
在一个Chrome示例应用程序中可以找到，尽管这意味着对于更大的数据块，您可以接受异步转换。
/**
* Converts an array buffer to a string
*
* @private
* @param {ArrayBuffer} buf The buffer to convert
* @param {Function} callback The function to call when conversion is complete
*/
function _arrayBufferToString(buf, callback) {
var bb = new Blob([new Uint8Array(buf)]);
var f = new FileReader();
f.onload = function(e) {
callback(e.target.result);
};
f.readAsText(bb);
}
我很沮丧地看到，人们没有显示如何双向或显示事情的工作在不平凡的UTF8字符串。我在codereview.stackexchange.com上找到了一个帖子，其中有一些运行良好的代码。我用它把古老的符文转换成字节，在字节上测试一些加密，然后把东西转换回字符串。工作代码在github这里。为了清晰起见，我重命名了这些方法:
// https://codereview.stackexchange.com/a/3589/75693
function bytesToSring(bytes) {
var chars = [];
for(var i = 0, n = bytes.length; i < n;) {
chars.push(((bytes[i++] & 0xff) << 8) | (bytes[i++] & 0xff));
}
return String.fromCharCode.apply(null, chars);
}
// https://codereview.stackexchange.com/a/3589/75693
function stringToBytes(str) {
var bytes = [];
for(var i = 0, n = str.length; i < n; i++) {
var char = str.charCodeAt(i);
bytes.push(char >>> 8, char & 0xFF);
}
return bytes;
}
单元测试使用这个UTF-8字符串:
// http://kermitproject.org/utf8.html
// From the Anglo-Saxon Rune Poem (Rune version)
const secretUtf8 = `ᚠᛇᚻ᛫ᛒᛦᚦ᛫ᚠᚱᚩᚠᚢᚱ᛫ᚠᛁᚱᚪ᛫ᚷᛖᚻᚹᛦᛚᚳᚢᛗ
ᛋᚳᛖᚪᛚ᛫ᚦᛖᚪᚻ᛫ᛗᚪᚾᚾᚪ᛫ᚷᛖᚻᚹᛦᛚᚳ᛫ᛗᛁᚳᛚᚢᚾ᛫ᚻᛦᛏ᛫ᛞᚫᛚᚪᚾ
ᚷᛁᚠ᛫ᚻᛖ᛫ᚹᛁᛚᛖ᛫ᚠᚩᚱ᛫ᛞᚱᛁᚻᛏᚾᛖ᛫ᛞᚩᛗᛖᛋ᛫ᚻᛚᛇᛏᚪᚾ᛬`;
请注意，字符串长度只有117个字符，但编码时字节长度为234。
如果我取消console.log行注释，我可以看到解码的字符串与编码的字符串相同(通过Shamir的秘密共享算法传递的字节!):
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