Internet DRAFT - draft-ietf-cellar-control
draft-ietf-cellar-control
CELLAR Group S. Lhomme
Internet-Draft
Intended status: Standards Track M. Bunkus
Expires: 7 June 2023
D. Rice
4 December 2022
Matroska Media Container Control Track Specifications
draft-ietf-cellar-control-02
Abstract
This document defines the Control Track usage found in the Matroska
container.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 7 June 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Status of this document . . . . . . . . . . . . . . . . . . . 2
3. Security Considerations . . . . . . . . . . . . . . . . . . . 2
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 2
5. Notation and Conventions . . . . . . . . . . . . . . . . . . 3
5.1. title: Control Tracks . . . . . . . . . . . . . . . . . . 3
6. Edition Flags . . . . . . . . . . . . . . . . . . . . . . . . 3
6.1. EditionFlagHidden . . . . . . . . . . . . . . . . . . . . 3
6.2. EditionFlagDefault . . . . . . . . . . . . . . . . . . . 4
6.3. Default Edition . . . . . . . . . . . . . . . . . . . . . 4
7. Chapter Flags . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. ChapterFlagEnabled . . . . . . . . . . . . . . . . . . . 6
8. Matroska Schema . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Segment . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1.1. Chapters . . . . . . . . . . . . . . . . . . . . . . 7
8.1.1.1. EditionEntry . . . . . . . . . . . . . . . . . . 7
8.2. title: Menu Specifications . . . . . . . . . . . . . . . 7
9. Menu Specifications . . . . . . . . . . . . . . . . . . . . . 8
9.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 8
9.1.1. Highlights/Hotspots . . . . . . . . . . . . . . . . . 8
9.1.2. Playback features . . . . . . . . . . . . . . . . . . 9
9.1.3. Player requirements . . . . . . . . . . . . . . . . . 9
9.2. Working Graph . . . . . . . . . . . . . . . . . . . . . . 9
10. Normative References . . . . . . . . . . . . . . . . . . . . 9
11. Informative References . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
2. Status of this document
This document is a work-in-progress specification defining the
Matroska file format as part of the IETF Cellar working group
(https://datatracker.ietf.org/wg/cellar/charter/). It uses basic
elements and concept already defined in the Matroska specifications
defined by this workgroup [Matroska].
3. Security Considerations
This document inherits security considerations from the EBML and
Matroska documents.
4. IANA Considerations
To be determined.
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5. Notation and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
5.1. title: Control Tracks
6. Edition Flags
6.1. EditionFlagHidden
When the EditionFlagHidden flag is set to false it means the Edition
is visible and selectable in a Matroska Player. All ChapterAtoms
Elements MUST be interpreted with their own ChapterFlagHidden flags.
+===================+=======+======+=========+
| ChapterFlagHidden | False | True | visible |
+===================+=======+======+=========+
| Chapter 1 | X | | yes |
+-------------------+-------+------+---------+
| Chapter 2 | | X | no |
+-------------------+-------+------+---------+
Table 1: ChapterAtom visibility to the user
When the EditionFlagHidden flag is set to true the Edition is hidden
and SHOULD NOT be selectable in a Matroska Player. If all Editions
EditionFlagHidden flags are set to true, there is no visible Edition.
In this case all ChapterAtoms Elements MUST also be interpreted as if
their ChapterFlagHidden flag is also set to true, regardless with
their own ChapterFlagHidden flags.
+===================+=======+======+=========+
| ChapterFlagHidden | False | True | visible |
+===================+=======+======+=========+
| Chapter 1 | X | | no |
+-------------------+-------+------+---------+
| Chapter 2 | | X | no |
+-------------------+-------+------+---------+
Table 2: ChapterAtom visibility in hidden
editions
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6.2. EditionFlagDefault
It is RECOMMENDED that no more than one Edition have an
EditionFlagDefault Flag set to true. The first Edition with both the
EditionFlagDefault Flag set to true and the EditionFlagHidden Flag
set to false is the Default Edition. When all EditionFlagDefault
Flags are set to false, then the first Edition with the
EditionFlagHidden Flag set to false is the Default Edition. The
Default Edition is the edition that should be used for playback by
default.
6.3. Default Edition
The Default Edition is the Edition that a Matroska Player SHOULD use
for playback by default.
The first Edition with both the EditionFlagDefault flag set to true
and the EditionFlagHidden flag set to false is the Default Edition.
When all EditionFlagDefault flags are set to false and all
EditionFlagHidden flag set to true, then the first Edition is the
Default Edition. When all EditionFlagHidden flags are set to true,
then the first Edition with the EditionFlagDefault flag set to true
is the Default Edition. When all EditionFlagDefault flags are set to
false, then the first Edition with the EditionFlagHidden flag set to
false is the Default Edition. When there is no Edition with a
EditionFlagDefault flag are set to true and a EditionFlagHidden flags
are set to false, then the first Edition with the EditionFlagHidden
flag set to false is the Default Edition.
In other words, in case the Default Edition is not obvious, the first
Edition with a EditionFlagHidden flag set to false SHOULD be
preferred.
+===========+============+=============+=================+
| Edition | FlagHidden | FlagDefault | Default Edition |
+===========+============+=============+=================+
| Edition 1 | true | true | |
+-----------+------------+-------------+-----------------+
| Edition 2 | true | true | |
+-----------+------------+-------------+-----------------+
| Edition 3 | false | true | X |
+-----------+------------+-------------+-----------------+
Table 3: Default edition, some visible, all default
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+===========+============+=============+=================+
| Edition | FlagHidden | FlagDefault | Default Edition |
+===========+============+=============+=================+
| Edition 1 | true | false | X |
+-----------+------------+-------------+-----------------+
| Edition 2 | true | false | |
+-----------+------------+-------------+-----------------+
| Edition 3 | true | false | |
+-----------+------------+-------------+-----------------+
Table 4: Default edition, all hidden, no default
+===========+============+=============+=================+
| Edition | FlagHidden | FlagDefault | Default Edition |
+===========+============+=============+=================+
| Edition 1 | true | false | |
+-----------+------------+-------------+-----------------+
| Edition 2 | true | true | X |
+-----------+------------+-------------+-----------------+
| Edition 3 | true | false | |
+-----------+------------+-------------+-----------------+
Table 5: Default edition, all hidden, with default
+===========+============+=============+=================+
| Edition | FlagHidden | FlagDefault | Default Edition |
+===========+============+=============+=================+
| Edition 1 | true | false | |
+-----------+------------+-------------+-----------------+
| Edition 2 | false | false | X |
+-----------+------------+-------------+-----------------+
| Edition 3 | false | false | |
+-----------+------------+-------------+-----------------+
Table 6: Default edition, some visible, no default
+===========+============+=============+=================+
| Edition | FlagHidden | FlagDefault | Default Edition |
+===========+============+=============+=================+
| Edition 1 | true | false | |
+-----------+------------+-------------+-----------------+
| Edition 2 | true | true | |
+-----------+------------+-------------+-----------------+
| Edition 3 | false | false | X |
+-----------+------------+-------------+-----------------+
Table 7: Default edition, some visible, some default
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7. Chapter Flags
If a Control Track toggles the parent's ChapterFlagHidden flag to
false, then only the parent ChapterAtom and its second child
ChapterAtom MUST be interpreted as if ChapterFlagHidden is set to
false. The first child ChapterAtom, which has the ChapterFlagHidden
flag set to true, retains its value until its value is toggled to
false by a Control Track.
The ChapterFlagEnabled value can be toggled by control tracks.
7.1. ChapterFlagEnabled
If the ChapterFlagEnabled flag is set to false a Matroska Player MUST
NOT use this Chapter and all his Nested Chapters. For Simple
Chapters, a Matroska Player MAY display this enabled Chapter with a
marker in the timeline. For Ordered Chapters a Matroska Player MUST
use the duration of this enabled Chapter.
+==========================+====================+======+
| Chapter + Nested Chapter | ChapterFlagEnabled | used |
+==========================+====================+======+
| Chapter 1 | true | yes |
+--------------------------+--------------------+------+
| +Nested Chapter 1.1 | true | yes |
+--------------------------+--------------------+------+
| +Nested Chapter 1.2 | false | no |
+--------------------------+--------------------+------+
| ++Nested Chapter 1.2.1 | true | no |
+--------------------------+--------------------+------+
| ++Nested Chapter 1.2.2 | false | no |
+--------------------------+--------------------+------+
| Chapter 2 | false | no |
+--------------------------+--------------------+------+
| +Nested Chapter 2.1 | true | no |
+--------------------------+--------------------+------+
| +Nested Chapter 2.2 | true | no |
+--------------------------+--------------------+------+
Table 8
8. Matroska Schema
Extra elements used to handle Control Tracks and advanced selection
features:
8.1. Segment
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8.1.1. Chapters
8.1.1.1. EditionEntry
8.1.1.1.1. EditionFlagHidden Element
id / type / default: 0x45BD / uinteger / 0
range: 0-1
path: \Segment\Chapters\EditionEntry\EditionFlagHidden
minOccurs / maxOccurs: 1 / 1
definition: Set to 1 if an edition is hidden. Hidden editions
SHOULD NOT be available to the user interface (but still to
Control Tracks; see Section 7 on Chapter flags).
8.1.1.1.1.1. ChapterFlagEnabled Element
id / type / default: 0x4598 / uinteger / 1
range: 0-1
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterFlagEnabled
minOccurs / maxOccurs: 1 / 1
definition: Set to 1 if the chapter is enabled. It can be enabled/
disabled by a Control Track. When disabled, the movie SHOULD skip
all the content between the TimeStart and TimeEnd of this chapter;
see Section 7 on Chapter flags.
8.1.1.1.1.2. ChapterTrack Element
id / type: 0x8F / master
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTrack
maxOccurs: 1
definition: List of tracks on which the chapter applies. If this
Element is not present, all tracks apply
8.1.1.1.1.3. ChapterTrackUID Element
id / type: 0x89 / uinteger
range: not 0
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTrack\Chapt
erTrackUID
minOccurs: 1
definition: UID of the Track to apply this chapter to. In the
absence of a control track, choosing this chapter will select the
listed Tracks and deselect unlisted tracks. Absence of this
Element indicates that the Chapter SHOULD be applied to any
currently used Tracks.
8.2. title: Menu Specifications
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9. Menu Specifications
This document is a _draft of the Menu system_ that will be the
default one in Matroska. As it will just be composed of a Control
Track, it will be seen as a "codec" and could be replaced later by
something else if needed.
A menu is like what you see on DVDs [DVD-Video], when you have some
screens to select the audio format, subtitles or scene selection.
9.1. Requirements
What we'll try to have is a system that can do almost everything done
on a DVD, or more, or better, or drop the unused features if
necessary.
As the name suggests, a Control Track is a track that can control the
playback of the file and/or all the playback features. To make it as
simple as possible for Matroska Players, the Control Track will just
give orders to the Matroska Player and get the actions associated
with the highlights/hotspots.
9.1.1. Highlights/Hotspots
A highlight is basically a rectangle/key associated with an action
UID. When that rectangle/key is activated, the Matroska Player send
the UID of the action to the Control Track handler (codec). The fact
that it can also be a key means that even for audio only files, a
keyboard shortcut or button panel could be used for menus. But in
that case, the hotspot will have to be associated with a name to
display.
This highlight is sent from the Control Track to the Matroska Player.
Then the Matroska Player has to handle that highlight until it's
deactivated; see Section 9.1.2.
The highlight contains a UID of the action, a displayable name (UTF-
8), an associated key (list of keys to be defined, probably
up/down/left/right/select), a screen position/range and an image to
display. The image will be displayed either when the user place the
mouse over the rectangle (or any other shape), or when an option of
the screen is selected (not activated). There could be a second
image used when the option is activated. And there could be a third
image that can serve as background. This way you could have a still
image (like in some DVDs [DVD-Video]) for the menu and behind that
image blank video (small bitrate).
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When a highlight is activated by the user, the Matroska Player has to
send the UID of the action to the Control Track. Then the Control
Track codec will handle the action and possibly give new orders to
the Matroska Player.
The format used for storing images SHOULD be extensible. For the
moment we'll use PNG and BMP, both with alpha channel.
9.1.2. Playback features
All the following features will be sent from the Control Track to the
Matroska Player :
* Jump to chapter (UID, prev, next, number)
* Disable all tracks of a kind (audio, video, subtitle)
* Enable track UID (the kind doesn't matter)
* Define/Disable a highlight
* Enable/Disable jumping
* Enable/Disable track selection of a kind
* Select Edition ID (see chapters)
* Pause playback
* Stop playback
* Enable/Disable a Chapter UID
* Hide/Unhide a Chapter UID
All the actions will be written in a normal Matroska track, with a
timestamp. A "Menu Frame" SHOULD be able to contain more that one
action/highlight for a given timestamp. (to be determined, EBML
format structure)
9.1.3. Player requirements
Some Matroska Players might not support the control track. That mean
they will play the active/looped parts as part of the data. So I
suggest putting the active/looped parts of a movie at the end of a
movie. When a Menu-aware Matroska Player encounter the default
Control Track of a Matroska file, the first order SHOULD be to jump
at the start of the active/looped part of the movie.
9.2. Working Graph
Matroska Source file -> Control Track <-> Player.
-> other tracks -> rendered
10. Normative References
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[Matroska] Lhomme, S., Bunkus, M., and D. Rice, "Media Container
Specifications", Work in Progress, Internet-Draft, draft-
ietf-cellar-matroska-10, 1 May 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-cellar-
matroska-10>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
11. Informative References
[DVD-Video]
DVD Forum, "DVD-Books: Part 3 DVD-Video Book", 1 November
1995, <http://www.dvdforum.org/>.
Authors' Addresses
Steve Lhomme
Email: slhomme@matroska.org
Moritz Bunkus
Email: moritz@bunkus.org
Dave Rice
Email: dave@dericed.com
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