FFmpeg音视频核心技术精讲与实战

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FFmpeg音视频核心技术精讲与实战

'use strict'; var http = require('http'); //端口号 var port = process.env.PORT || 1337; /**

回调函数的运用 */ //回调函数 var fs = require("fs");

//回调函数 fs.readFile('./input.txt', function (err, data) { if (err) return console.error(err); console.log(data.toString()); }); /end**/

/**

事情驱动程序 */ //引入events模块 var events = require('events'); //创立eventEmitter对象 var eventEmitter = new events.EventEmitter();

//创立时间处置程序 var connectHandler = function conneted() { console.log("connect success.");

//触发 data_received 事情
eventEmitter.emit('data_received');

}

//绑定connection 事情处置程序 eventEmitter.on('connection', connectHandler);

//运用匿名函数绑定data_received事情 eventEmitter.on('data_received', function () { console.log('received data1 success.'); });

eventEmitter.on('data_received', function () { console.log('received data2 success.'); });

//触发connection事情 setTimeout(function () { eventEmitter.emit('connection'); }, 1000);

console.log('program run over.'); /end**/

/Buffer对象/ var buf = Buffer.alloc(26); for (var i = 0; i < 26; i++) { buf[i] = i + 97; }

console.log(buf.toString('ascii'));// 输出: abcdefghijklmnopqrstuvwxyz console.log(buf.toString('ascii', 0, 5)); // 输出: abcde console.log(buf.toString('utf8', 0, 5)); // 输出: abcde console.log(buf.toString(undefined, 0, 5)); // 运用 'utf8' 编码, 并输出: abcde

//buffer转Json var buffer2json = Buffer.from('aabbc!'); var _json = buffer2json.toJSON(buffer2json); console.log("The Buffer2Json is " + _json);

//缓冲区兼并 var buffer1 = Buffer.from('Me'); var buffer2 = Buffer.from(' QinShiHuang'); var buffer3 = Buffer.from(' DaQian'); var buffer4 = Buffer.concat([buffer1, buffer2, buffer3]); console.log("The concat result is " + buffer4.toString());

//缓冲区比拟 //返回一个数字，表示 buf 在 otherBuffer 之前，之后或相同。 var cBuffer1 = Buffer.from('ABC'); var cBuffer2 = Buffer.from('ABCD'); console.log("The compare result is ") var compareResult = cBuffer1.compare(cBuffer2); if (compareResult < 0) { console.log(cBuffer1 + ' at before of ' + cBuffer2); } else if (compareResult == 0) { console.log(cBuffer1 + ' at after of ' + cBuffer2); } else { console.log(cBuffer1 + ' is equal of ' + cBuffer2); }

//拷贝缓冲区 var copyBuffer1 = Buffer.from('I Hate You!'); var copyBuffer2 = Buffer.from('Love'); //将 buf2 插入到 buf1 指定位置上 copyBuffer2.copy(copyBuffer1, 2); console.log("The copy content is " + copyBuffer1.toString());

//缓冲区裁剪 var sliceBuffer1 = Buffer.from('you are'); var sliceBuffer2 = sliceBuffer1.slice(0, 3); console.log("sliceBuffer2 content : " + sliceBuffer2.toString()); /end**/

/Stream流start***/ var streamData = ''; //创立可读流 var readerStream = fs.createReadStream('./input.txt'); //设置编码为utf-8 readerStream.setEncoding('UTF8'); //处置流事情-->data,end,and error readerStream.on('data', function (chunk) { streamData += chunk; }); readerStream.on('end', function () { console.log(streamData); }); readerStream.on('error', function (err) { console.log(err.stack); }); console.log('stream run over!');

//写入流 var writeData = 'this is a very good thing,dont worry'; // 创立一个能够写入的流，写入到文件 output.txt 中 var writeStream = fs.createWriteStream('./output.txt'); // 运用 utf8 编码写入数据 writeStream.write(writeData, 'UTF8'); // 标志文件末尾 writeStream.end(); // 处置流事情 --> finish, and error writeStream.on('finish', function () { console.log('Write success.'); }); writeStream.on('error', function (err) { console.log(err.stack); });

//管道流 //读取一个文件并写入另一个文件 //创立一个可读流 var rStream = fs.createReadStream('./input.txt'); //创立一个可写流 var wStream = fs.createWriteStream('./output1.txt'); //管道读写操作 //读取input.txt的文件内容，并将内容写入output.txt文件中 rStream.pipe(wStream); console.log("Read and Write Over!");

//链式流 //紧缩文件 var zlib = require('zlib'); //紧缩input.txt文件为input.txt.gz fs.createReadStream('./input.txt') .pipe(zlib.createGzip()) .pipe(fs.createWriteStream('./input.txt.gz')); console.log('zip complete!'); //解压文件 //fs.createReadStream('./input.txt.gz') // .pipe(zlib.createGunzip()) // .pipe(fs.createWriteStream('./zip_input.txt')); //console.log('zipGun complete!');

/Stream流end***/

/模块系统创立对象start***/ var Hello = require('./hello'); var hello = new Hello(); hello.setName('Wang Da Niang'); hello.sayHello(); /模块系统创立对象end***/

/Node.js函数start***/ //一个函数能够作为另一个函数的参数 function say(word) { console.log(word); } function execute(someFunction, value) { someFunction(value); } execute(say, 'WoZhenDeAiNi!');

//匿名函数,办法躲藏在参数中 execute(function (word) { console.log('NiMing:' + word); }, 'BuXiangShuoHua') /Node.js函数end***/

/*******************Node.js全局对象start **********************/ //输出全局变量_filename的值，__filename 表示当前正在执行的脚本的文件名。它将输出文件所在位置的绝对途径，且和命令行参数所指定的文件名不一定相同。假如在模块中，返回的值是模块文件的途径。 console.log(__filename); // 输出全局变量 __dirname 的值，__dirname 表示当前执行脚本所在的目录。 console.log(__dirname);

//Process属性 //输出到终端 process.stdout.write("Hello World!\n") //经过参数读取 process.argv.forEach(function (val, index, array) { console.log(index + ':' + val); }); //获取执行途径 console.log(process.exePath); //平台信息 console.log(process.platform);

//Process办法 //输出当前目录 console.log('current direction is :' + process.cwd()); //输出当前版本 console.log('current version is :' + process.version); //输出内存运用状况 console.log('current neicun is :'+process.memoryUsage()); /Node.js全局对象end***/

/util.inherits继承办法start**/ var util = require('util'); function Base() { this.name = 'GuoJia'; this.base = 1995; this.sayHello = function () { console.log('Hello' + this.name); }; } Base.prototype.showName = function () { console.log(this.name); } function Sub() { this.name = 'Ai'; } //使Sub继承于Base util.inherits(Sub, Base); var objBase = new Base(); objBase.showName(); objBase.sayHello(); console.log(objBase); var objSub = new Sub(); objBase.showName(); //objSub.sayHello(); console.log(objSub);

/util.inherits继承办法end**/

/util.inspect办法start**/ //将恣意对象转换为字符串的办法，通常用于调试和错误输出 function Person() { this.name = 'LiXiuQi'; this.toString = function () { return this.name; }; } var obj = new Person(); console.log(util.inspect(obj)); console.log(util.inspect(obj, true)); /util.inspect办法end**/

/启动效劳start***/ var url = require("url"); var route = require('./route.js'); function start(route) { function onRequest(request, response) { var pathname = url.parse(request.url).pathname; console.log("Request for " + pathname + " received."); //处置url地址参数 route(pathname);

    // 发送 HTTP 头部 
    // HTTP 状态值: 200 : OK
    // 内容类型: text/plain
    response.writeHead(200, { 'Content-Type': 'text/plain' });

    // 发送响应数据 "Hello World"
    response.end('Hello World\n');
}
//创立效劳
http.createServer(onRequest).listen(port);

} start(route.route);

/启动效劳end***/

// 终端打印信息 console.info("hi this is the first application!");

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