Chapter Extension

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(Added section headings and details of format + tidy)
(Changed to webvtt-style "-->" timestamp separators (with no whitespace))
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We therefore propose an extensions to VorbisComment for transporting chapters. We introduce VorbisComment fields called CHAPTERxxx and CHAPTERxxxNAME with xxx being a number between 000 and 999. (1000 chapters are assumed to be sufficient.)
We therefore propose an extensions to VorbisComment for transporting chapters. We introduce VorbisComment fields called CHAPTERxxx and CHAPTERxxxNAME with xxx being a number between 000 and 999. (1000 chapters are assumed to be sufficient.)
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The value for the CHAPTERxxx field name is the start time of the chapter (Hour:Min:DecimalSeconds), a dash (U+002D), and the end time (Hour:Min:DecimalSeconds). See the [[#Examples|examples]] below.
+
The value for the CHAPTERxxx field name is the start time of the chapter (Hour:Min:DecimalSeconds), "-->" (U+002D, U+002D, U+003E), and the end time (Hour:Min:DecimalSeconds). See the [[#Examples|examples]] below.
The value for the CHAPTERxxxNAME field name is just a text string (8 bit clean UTF-8 encoded values, as is required for VorbisComments).
The value for the CHAPTERxxxNAME field name is just a text string (8 bit clean UTF-8 encoded values, as is required for VorbisComments).
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An example chapter file with two sequential chapters:  
An example chapter file with two sequential chapters:  
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  CHAPTER001=00:00:00.000-00:05:00.000
+
  CHAPTER001=00:00:00.000-->00:05:00.000
  CHAPTER001NAME=Chapter 1
  CHAPTER001NAME=Chapter 1
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  CHAPTER002=00:05:00.000-00:10:00.000
+
  CHAPTER002=00:05:00.000-->00:10:00.000
  CHAPTER002NAME=Chapter 2
  CHAPTER002NAME=Chapter 2
Another example chapter file with a chapter and three hierarchically structured subchapters:  
Another example chapter file with a chapter and three hierarchically structured subchapters:  
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  CHAPTER001=00:00:00.000-00:06:00.000
+
  CHAPTER001=00:00:00.000-->00:06:00.000
  CHAPTER001NAME=Chapter 1
  CHAPTER001NAME=Chapter 1
-
  CHAPTER002=00:00:00.000-00:02:00.000
+
  CHAPTER002=00:00:00.000-->00:02:00.000
  CHAPTER002NAME=Chapter 1.1
  CHAPTER002NAME=Chapter 1.1
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  CHAPTER003=00:00:02.000-00:04:00.000
+
  CHAPTER003=00:00:02.000-->00:04:00.000
  CHAPTER003NAME=Chapter 1.2
  CHAPTER003NAME=Chapter 1.2
-
  CHAPTER004=00:00:04.000-00:06:00.000
+
  CHAPTER004=00:00:04.000-->00:06:00.000
  CHAPTER004NAME=Chapter 1.3
  CHAPTER004NAME=Chapter 1.3

Revision as of 22:16, 9 March 2012

Chapters are a means of providing direct and semantically relevant navigation points for a media file. On particular use case are so-called "enhanced podcasts", i.e. audio files with additional chapter markers.

Chapters are typically provided for a recorded file, not for a live resource.

Since chapters are used for navigation - in particular to avoid having to listen to large amounts of undesired content in order to get to desired content - it is important that the information about chapters is available at the start of a media file to be able to be displayed without having to decode the media file. Therefore, we regard chapters as header-style metadata.

Header-style metadata has traditionally been transported in VorbisComment headers inside Ogg.

Format

We therefore propose an extensions to VorbisComment for transporting chapters. We introduce VorbisComment fields called CHAPTERxxx and CHAPTERxxxNAME with xxx being a number between 000 and 999. (1000 chapters are assumed to be sufficient.)

The value for the CHAPTERxxx field name is the start time of the chapter (Hour:Min:DecimalSeconds), "-->" (U+002D, U+002D, U+003E), and the end time (Hour:Min:DecimalSeconds). See the examples below.

The value for the CHAPTERxxxNAME field name is just a text string (8 bit clean UTF-8 encoded values, as is required for VorbisComments).

This should basically support the same input format that Matroska chapters support, too.

Examples

An example chapter file with two sequential chapters:

CHAPTER001=00:00:00.000-->00:05:00.000
CHAPTER001NAME=Chapter 1
CHAPTER002=00:05:00.000-->00:10:00.000
CHAPTER002NAME=Chapter 2

Another example chapter file with a chapter and three hierarchically structured subchapters:

CHAPTER001=00:00:00.000-->00:06:00.000
CHAPTER001NAME=Chapter 1
CHAPTER002=00:00:00.000-->00:02:00.000
CHAPTER002NAME=Chapter 1.1
CHAPTER003=00:00:02.000-->00:04:00.000
CHAPTER003NAME=Chapter 1.2
CHAPTER004=00:00:04.000-->00:06:00.000
CHAPTER004NAME=Chapter 1.3

WebVTT

A more modern means of specifying chapters is through WebVTT files that use cues with chapter titles.

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