@nuab/smpte.js

smpte.js

Easily deal with Timecode SMPTE format in js. If you need a PHP lib, check out fireworkweb/smpte.php.

Installation

Using npm or yarn:

npm install smpte.js

yarn add smpte.js

Usage

Example

Using ES6 sintax:

import SMPTE from 'smpte.js';

SMPTE.defaults.frameRate = 29.97;
SMPTE.defaults.dropFrame = true;

let timecode = new SMPTE(1);
let timecodeToAdd = new SMPTE('00;00;00;02');
let anotherTimecodeToAdd = SMPTE.fromSeconds(1);

console.log(
    timecode
        .add(timecodeToAdd)
        .add(anotherTimecodeToAdd)
        .toString('00:00:00;00')
);
// 00:00:01;03

let invalidTm = new SMPTE('00:01:00:23', 24, true);
// Error: Only 29.97 frame rate has drop frame support

let invalidTm = new SMPTE('00:01:00:59', 60, false);
// Error: Frame rate not supported

let invalidTm = new SMPTE(-1440, 24, false);
// Error: Negative frames not supported

let invalidTm = new SMPTE('00:00:00:24', 24, false);
// Error: Invalid timecode

Object Instantiation

SMPTE objects can be instatianted from frame count, date object, seconds, timecode integer parts or directly from timecode string.

// Frame count
let tm = SMPTE.fromFrames(1440, 24, false);

// Date object
let tm = SMPTE.fromDate(Date.now(), 24, false);

// Seconds
let tm = SMPTE.fromSeconds(60, 24, false);

// Timecode integer parts
let tm = SMPTE.fromParts(0, 1, 0, 0, 24, false);

// Timecode string
let tm = SMPTE.fromTimecode('00:01:00:00', 24, false);

// or using the constructor
let tm = new SMPTE('00:01:00:00', 24, false);

Properties

SMPTE objects provide the following properties once an object is instantiated:

Property	Type	get	set	Description
frameCount	Number	✅	✅	Total number of frames
hours	Number	✅	✅	Hours number
minutes	Number	✅	✅	Minutes number
seconds	Number	✅	✅	Seconds number
frames	Number	✅	✅	Frames number
durationInSeconds	Number	✅	❌	Timecode duration in seconds
attributes.df	Boolean	✅	✅	Global drop frame indicator
attributes.frameRate	Number	✅	✅	Global Frame rate in FPS

Methods

Each SMPTE object provides the following methods:

addFromSeconds(seconds)

Adds a number of seconds to the current timecode object.

• seconds: Number indicating the seconds to be added.
• return: Reference to the changed SMPTE object

Example:

let tc = SMPTE.fromSeconds(2, 24, false);
console.log(tc.addFromSeconds(2).toString())
// 00:00:04:00

subtractFromSeconds(seconds)

Substracts a timecode or a frame count from the current SMPTE object.

• seconds: Number indicating the seconds to be subtracted.
• return: Reference to the changed SMPTE object

Example:

let tc = SMPTE.fromSeconds(2, 24, false);
console.log(tc.subtractFromSeconds(2).toString())
// 00:00:00:00

add(time, operation = 1)

Adds a timecode or a frame count to the current SMPTE object.

• time: Number|String|SMPTE indicating the value to be added.
• operation: Number used to get the sign of the time.
• return: Reference to the changed SMPTE object

Example:

let tc = SMPTE.fromTimecode('00:01:00:00', 24, false);
console.log(tc.add('00:00:30:00').toString())
// 00:01:30:00

subtract(time)

Substracts a timecode or a frame count from the current SMPTE object.

• time: Number|String|SMPTE indicating the value to be subtracted.
• return: Reference to the altered SMPTE object

Example:

let tc = SMPTE.fromTimecode('00:00:01:00', 24, false);
console.log(tc.subtract(4).toString())
// 00:00:00:20

toString(format = undefined)

Returns a string with the SMPTE timecode representation.

• format: String mask to form the string.
• return: Timecode string.

Example:

console.log(new SMPTE(48, 24, false).toString())
// 00:00:02:00

toDate()

Converts a SMPTE object to a date object.

• return: Respective Date object.

console.log(new SMPTE(48, 24, false).toDate().getSeconds())
// 2

isTimecodeFormatValid(timecode, df) - static

Checks if a timecode string is in a valid format.

• timecode: String to be evaluated.
• df: Boolean indicating if is drop frame representation.
• return: Boolean.

console.log(SMPTE.isTimecodeFormatValid('24:59:59:29', false));
// false
console.log(SMPTE.isTimecodeFormatValid('23:59:59:29', false));
// true

console.log(SMPTE.isTimecodeFormatValid('24:59:59:29', true));
// false
console.log(SMPTE.isTimecodeFormatValid('24:59:59;29', true));
// true

isValidTimecode(timecode, fr = defaults.frameRate, df = defaults.dropFrame) - static

Checks if a timecode is valid according to SMPTE standard.

• timecode: String to be evaluated.
• fr: Number indicating the frame rate.
• df: Boolean indicating if is drop frame representation.
• return: Boolean.

console.log(SMPTE.isValidTimecode('23:59:59:24', 24, false));
// false
console.log(SMPTE.isValidTimecode('23:59:59:23', 24, false));
// true

frameCountFromTimecode(timecode, fr = defaults.frameRate, df = defaults.dropFrame) - static

Gets the frame count given a timecode string.

• timecode: String timecode.
• fr: Number indicating the frame rate.
• df: Boolean indicating if is drop frame representation.
• return: Number.

console.log(SMPTE.frameCountFromTimecode('00:01:00;02', 29.97, true))
// 1800
console.log(SMPTE.frameCountFromTimecode('00:01:00:00', 29.97, false))
// 1800

isFramerateSupported(framerate) - static

Checks if a frame rate is supported.

• framerate: Number indicating the frame rate.
• return: Boolean.

console.log(SMPTE.isFramerateSupported(59.94))
// false
console.log(SMPTE.isFramerateSupported(25))
// true

Default values

You can easily change the default value accessing the static default object from the SMPTE class and change the frameRate or the dropFrame property.

import SMPTE from 'smpte.js';

SMPTE.defaults.frameRate = 29.97;
SMPTE.defaults.dropFrame = true;

Contributing

All contribution is welcome, please feel free to open tickets and pull requests.

License

MIT.