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Stream - 操作處理

Readstream / writestream​

音視頻文件讀寫，stream 的概念，不是一次讀寫入全部的檔案內容，而是將其拆成好幾個 chunk，放入 buffer。等到部份的 chunk 讀寫完後，再從 buffer 中抓一些 chunk 出來讀寫

const   fs              = require ('fs');
const   path            = require ('path');

const   readable        = fs.createReadStream (path.join(__dirname, 'sample-1.mp4'), { encoding: null, highWaterMark: 20 * 1024 });
const   writable        = fs.createWriteStream (path.join(__dirname, 'sample-1-copy.mp4'));
const   videoSize       = fs.statSync ('sample-1.mp4').size;

readable.on ('data', function (chunk) {
        // console.log(chunk);
        writable.write(chunk);
});

// or
readable.pipe (writable);

Stream pipe API​

使用stream和pipe方式，執行文字檔壓縮寫入

const           fs                      = require ('fs');
const           zlib                    = require ('zlib');
const           path                    = require ('path');

fs.createReadStream('text.txt')
        .pipe(zlib.createGzip())
        .pipe(fs.createWriteStream('text.txt.gz'));