docs(example): add example on cutting time range of video with ffmpeg

example/time_range.js

@@ -0,0 +1,55 @@
+const readline = require('readline');
+const fs = require('fs');
+const cp = require('child_process');
+const ytdl = require('../');
+const ffmpeg = require('ffmpeg-static');
+
+const url = 'https://www.youtube.com/watch?v=mIiY6aGefvI';
+const timeStart = '00:01:00';
+const timeDuration = '00:00:10';
+const output = `${__dirname}/out.mkv`;
+
+const video = ytdl(url);
+
+// Print download progress.
+process.stdout.write('downloading video...');
+video.on('progress', (chunkLength, downloaded, total) => {
+  const percent = downloaded / total;
+  readline.cursorTo(process.stdout, 0);
+  process.stdout.write(`downloading video... ${(percent * 100).toFixed(2)}%`);
+});
+
+video.pipe(fs.createWriteStream(`${__dirname}/tmp.mp4`)).on('finish', () => {
+  const ffmpegProcess = cp.spawn(ffmpeg, [
+    '-y', '-v', 'error',
+    '-progress', 'pipe:3',
+    '-i', `${__dirname}/tmp.mp4`,
+    '-vcodec', 'copy', '-acodec', 'copy',
+    '-ss', timeStart, '-t', timeDuration,
+    '-f', 'matroska', 'pipe:4',
+  ], {
+    windowsHide: true,
+    stdio: [
+      'inherit', 'inherit', 'inherit',
+      'pipe', 'pipe',
+    ],
+  });
+
+  process.stdout.write('\n');
+  ffmpegProcess.stdio[3].on('data', chunk => {
+    readline.cursorTo(process.stdout, 0);
+    const args = chunk.toString().trim().split('\n')
+      .reduce((acc, line) => {
+        let parts = line.split('=');
+        acc[parts[0]] = parts[1];
+        return acc;
+      }, {});
+    process.stdout.write(`cutting video... ${args.progress}${' '.repeat(3)}`);
+  });
+
+  ffmpegProcess.on('close', () => {
+    process.stdout.write(`\nsaved to ${output}\n`);
+  });
+
+  ffmpegProcess.stdio[4].pipe(fs.createWriteStream(output));
+});