@mtillmann/chapters
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0.1.2 • Public • Published

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chapters

This is the core library of the chaptertool project and provides the functionality to handle the formats below.

Click here to open the web GUI or go install chaptertool locally for CLI use.

Supported formats

class description key ext info
ChaptersJson Podcasting 2.0 Chapters chaptersjson json spec
FFMetadata FFMetadata ffmpegdata txt spec
MatroskaXML Matroska XML chapters matroskaxml xml spec
MKVMergeXML MKVToolNix mkvmerge XML mkvmergexml xml spec
MKVMergeSimple MKVToolNix mkvmerge simple mkvmergesimple txt spec
WebVTT WebVTT Chapters webvtt vtt spec
Youtube Youtube Chapter Syntax youtube txt
FFMpegInfo FFMpegInfo ffmpeginfo txt read only, used internally
PySceneDetect PySceneDetect pyscenedetect csv project home
VorbisComment Vorbis Comment Format vorbiscomment txt spec
AppleChapters "Apple Chapters" applechapters xml source
ShutterEDL Shutter EDL edl edl source
PodloveSimpleChapters Podlove Simple Chapters psc xml spec
PodloveJson Podlove Simple Chapters JSON podlovejson json source
MP4Chaps MP4Chaps mp4chaps txt source
AppleHLS Apple HLS Chapters applehls json spec, partial support
Scenecut Scenecut format scenecut json source

Installation

npm i @mtillmann/chapters

Usage

import { ChaptersJson } from '@mtillmann/chapters';

const chapters = new ChaptersJson()
chapters.add({ startTime: 0, title: 'Intro' })
chapters.add({ startTime: 30, title: 'Some Topic' })
const json = chapters.toString()

Autoformat

Autoformat is a helper that can be used to automatically detect the format of a given input and return the corresponding class, key or a new instance of the detected class. It also provides a method to convert the input to a specific format.

import { Autoformat } from '@mtillmann/chapters'
import { WebVTT } from '@mtillmann/chapters'

const content = '<podcasting 2.0 chapters.json>...'
const instance = Autoformat.detect(content) // returns an instance of ChaptersJson
const instance2 = Autoformat.from(content) // returns an instance of ChaptersJson

const key = Autoformat.detect(content, 'key') // returns 'chaptersjson'
const className = Autoformat.detect(content, 'class') // returns ChaptersJson

const webVttString = 'WEBVTT...';

const autodetectedWebVtt = Autoformat.detect(webVttString) // returns an instance of WebVTT

const fail = Autoformat.as('chaptersjson', webVttString) // throws an error

const vtt = Autoformat.as('webvtt', webVttString) // returns an instance of WebVTT
const vtt2 = Autoformat.as(WebVTT, webVttString) // returns an instance of WebVTT

API

All formats support the following methods:

constructor (duration: number = 3600)

Creates a new instance of the class, optionally with a duration in seconds.

const chapters = (new ChaptersJson(3600)).from(input)

the constructor will not accept any input due to javascript's order of initialization which prevents the parse method from having access to cerain locally defined properties and methods.

static create (input?: string | MediaItem): MediaItem

Creates a new media item. This is the suggested way to create a media item from a string:

const chapters = MatroskaXML.create(input)
// chapters is now an instance of MatroskaXML

const chapterString = WebVTT.create(chapters).toString()
// chapterString is now a string representation of the chapters

from (input?: string | MediaItem): MediaItem

Populates the media item's chapters from the given input.

to (className: any): MediaItem

Converts the media item to another format.

add (chapter: Chapter): void

Adds a chapter.

addChapterAt (index: number, chapter: object = {}): number

Adds a chapter at the given index.

addChapterAtTime (time: number | string, chapter: object = {}): boolean

Adds a chapter at the given time.

remove (index: number): void

Removes the chapter at the given index.

bump (keepDuration: boolean = false): void

Updates the chapters and duration. Called automatically after adding or removing chapters.

endTime (index: number): number

Returns the end time for the chapter at the given index.

expandFirstToStart (): void

Expands the first chapter to start at 0.

applyChapterMinLength (seconds: number): object

Applies a minimum length to the chapters.

chapterExistsAtStartTime (time: number): boolean

Checks if a chapter exists at the given start time.

updateChapterStartTime (index: number, startTime: number | string): number | 'timeInUse'

Updates the start time for the chapter at the given index.

chapterIndexFromStartTime (startTime: number | string): number

Returns the index of the chapter with the given start time.

chapterIndexFromTime (time: number | string): null | number

Returns the index of the chapter at the given time.

toString([pretty: boolean][, options: object]): string

Convert the chapters to a string.
If pretty is true, the output will be formatted for better readability. Only supported by json and xml formats. Some formats support additional options:

ChapterJson toString() options

option type default description
imagePrefix string '' Prefix for image URLs
writeRedundantToc boolean false Write redundant TOC attributes
writeEndTimes boolean false Write end times

AppleChapters toString() options

option type default description
acUseTextAttr boolean false When set, the text-attribute will be used instead of node textContent

PySceneDetect toString() options

option type default description
psdFramerate number 23.976 Framerate of the video file
psdOmitTimecodes boolen false When set, the first line will be omitted

Scenecut toString() options

option type default description
frameRate number 30 Framerate of the video file
ptsScale number 1 PTS scale (See below)
score number 0.5 Score threshold

When asked about the ptsScale-value, ChatGPT said:

The number "1001" in the context of video processing and multimedia, especially in relation to frame rates and timecodes, is often associated with the NTSC color system used in North America and Japan. In this system, the frame rate is often described as "29.97 frames per second", but it's technically 30000/1001 frames per second, which is approximately 29.97 but not exactly. This is known as a "drop frame" rate, and the "1001" comes from this fractional frame rate.

When you use 1 the output pts will be the same as the frame number. When you use 1001 the output pts will be the same as the frame number multiplied by 1001.

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npm i @mtillmann/chapters

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