From 81ed57c77fbb01ad2dc144bd6b2101fe2c2babdb Mon Sep 17 00:00:00 2001
From: Utkarsh Verma <utkarsh.verma@hotmail.com>
Date: Fri, 29 Apr 2022 09:32:47 +0530
Subject: [PATCH] Initial commit

---
 LICENSE      |  20 ++++++++
 index.js     | 132 +++++++++++++++++++++++++++++++++++++++++++++++++++
 package.json |  10 ++++
 3 files changed, 162 insertions(+)
 create mode 100644 LICENSE
 create mode 100644 index.js
 create mode 100644 package.json

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..36abd50
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright (c) Utkarsh Verma
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
\ No newline at end of file
diff --git a/index.js b/index.js
new file mode 100644
index 0000000..a6ea61d
--- /dev/null
+++ b/index.js
@@ -0,0 +1,132 @@
+const videoFrames = async options => {
+
+	let index = 0;
+	let error = false;
+	let frames = [];
+	let interval;
+	let seekResolve;
+	let currentTime = 0;
+	let extractOffsets = false;
+
+	const isNumber = n => {
+		return +n + '' === n + '';
+	};
+
+	const isTimestamp = timestamp => {
+		return isNumber(timestamp) && +timestamp >= 0 && +timestamp <= video.duration;
+	};
+
+	const fallbackToDefault = (property, defaultValue) => {
+		options[property] = options.hasOwnProperty(property) ? options[property] : defaultValue;
+	};
+
+	// Buffer Video Element
+	const video = document.createElement('video');
+	video.src = options.url;
+	video.crossOrigin = 'anonymous';
+	video.onseeked = async () => {
+		if(seekResolve)
+			seekResolve();
+	};
+	video.onerror = () => {
+		error = true;
+	};
+
+	while((video.duration === Infinity || isNaN(video.duration)) && video.readyState < 2 && !error) {
+		await new Promise(r => setTimeout(r, 100));
+		video.currentTime = 10000000 * Math.random();
+	}
+
+	// Set options to default values if not set
+	fallbackToDefault('format', 'image/png');
+	fallbackToDefault('offsets', []);
+	fallbackToDefault('startTime', 0);
+	fallbackToDefault('endTime', video.duration);
+	fallbackToDefault('count', 1);
+
+	// Filter out invalid offsets
+	if(options.offsets.constructor !== Array)
+		options.offsets = [];
+	else
+		options.offsets = options.offsets.filter(offset => {
+			return isTimestamp(offset);
+		});
+
+	if(options.offsets.length !== 0)
+		extractOffsets = true;
+
+	// Check if start and end times are valid
+	if(!isTimestamp(options.startTime))
+		options.startTime = 0;
+
+	if(!isTimestamp(options.endTime))
+		options.endTime = video.duration;
+
+	if(options.startTime >= options.endTime) {
+		options.startTime = options.endTime;
+		options.count = 1;
+	}
+
+	// Convert count value to a positive integer (floor() or 0 if string)
+	options.count = Math.abs(~~options.count);
+
+	// Starting at startTime + interval and ending at endTime - interval
+	interval = (options.endTime - options.startTime) / (options.count + 1);
+
+	// Set Width and Height
+	let isWidthSet = options.hasOwnProperty('width');
+	let isHeightSet = options.hasOwnProperty('height');
+	let videoDimensionRatio = video.videoWidth / video.videoHeight;
+
+	// Reset Width and Height if not valid
+	if(isWidthSet && !isNumber(options.width))
+		isWidthSet = false;
+
+	if(isHeightSet && !isNumber(options.height))
+		isHeightSet = false;
+
+	if(!isWidthSet && !isHeightSet) {
+		// Both Width and Height not set
+		options.width = 128;
+		options.height = options.width / videoDimensionRatio;
+
+	} else if(isWidthSet && !isHeightSet) {
+		// Width set but Height not set
+		options.height = options.width / videoDimensionRatio;
+
+	} else if(!isWidthSet && isHeightSet) {
+		// Height set but Width not set
+		options.width = options.height * videoDimensionRatio;
+	}
+
+	// Float values
+	options.width = +options.width;
+	options.height = +options.height;
+
+	// Buffer Canvas Element
+	const canvas = document.createElement('canvas');
+	const context = canvas.getContext('2d');
+	canvas.width = options.width;
+	canvas.height = options.height;
+
+	return new Promise(async resolve => {
+
+		if(error)
+			resolve([]);
+
+		while(
+			(extractOffsets && index < options.offsets.length) ||
+			(!extractOffsets && index < options.count)
+		) {
+			video.currentTime = extractOffsets ? options.offsets[index] : options.startTime + (index + 1) * interval;
+			await new Promise(r => seekResolve = r);
+			context.clearRect(0, 0, canvas.width, canvas.height);
+			context.drawImage(video, 0, 0, canvas.width, canvas.height);
+			frames.push(canvas.toDataURL(options.format));
+			index ++;
+		}
+		resolve(frames);
+	});
+};
+
+module.exports = { videoFrames };
\ No newline at end of file
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..254d2c2
--- /dev/null
+++ b/package.json
@@ -0,0 +1,10 @@
+{
+  "name": "video-frames",
+  "version": "0.1.0",
+  "private": false,
+  "description": "Client side video frames extraction as base64 encoded images",
+  "author": "Utkarsh Verma",
+  "keywords": ["video", "frame", "client-side", "base64"],
+  "main": "index.js",
+  "license": "MIT"
+}