"Universal" or "Hybrid" DVD-A/V Spec Guides - Part 1. DVD-A Groups

[neil wilkes]

This is the first in a series of spec related posts I will be making over the next month or so, as it seems that a lot of folks are getting baffled by the specs as to what is & what is not spec compliant.
Given the manuals can best be described as confusing in places - owing to the Japaglese they seem to be written in, I will be making a series of posts and then attempting to explain any questions that arise from these as best as I can.
The manual quoted is from Sonic's DVD-Audio Creator, combined edition (3.0.11 or 3.0.12) but should be equally applicable to not only discWelder Chrome (although they will require interpolation due to Chrome being an abstraction layer tool - these will at least let you know why certain linking options are greyed out in custom menus, and why certain combinations result in an "illegal title" error - but they should (again, with a little thought) also apply to the earlier versions of DVD-Audio Creator that are floating around out there (3.0.5 for example) with no documentation - making them very, very difficult.

I will be happy to take "requests" for spec clarification, if anyone needs specific information...and I hope what is about to follow is not too impenetrable.

Anyway.
Number one on the list - DVD-A groups, what you can & cannot do, and how Video_TS content needs to be set up. I hope this helps, but please post if there are any questions.

Group Requirements

The DVD-Audio Specification allows up to nine groups per album. Each group can contain
between 1–99 tracks. Additional requirements determine whether a group is playable on the different DVD players.

Title Types and Groups

A given title can be referenced by more than one group. In some cases, groups simply
provide different paths through the same material on the disc; in other cases, titles in one group are not used in any other group. Ultimately, the organization of titles into groups is up to the producer, though it is subject to the constraints defined in the DVD-Audio Specification.
Under the specification, a group is only recognized by a given player if all titles in that group are playable by that player type. As shown in Table 1, there are three types of titles in DVDAudio, determined by the type of players on which the title plays.

Table 1: Title types

AOTT Audio-only Title with no motion-video content:
• Plays on audio-only DVD-Audio players and video-capable DVD-Audio players, but
not on DVD-Video players.
• Includes one or more audio tracks.
• One audio stream must be either LPCM or MLP.
• May contain still pictures (ASVs) that display as the audio plays, either slides (no
buttons) or menus (buttons).
• May not be in the same group as an AVTT Title.

AVTT Video-based Title in which the audio must be accompanied by the video:
• Plays on video-capable DVD-Audio players and DVD-Video players, but not on
audio-only DVD-Audio players.
• Only one allowed per group.
• Includes one or more video tracks (which can use up to nine angles), each defined
as a PTT.
• One audio stream must be either LPCM or Dolby Digital.
• An optional second audio stream can be LPCM, Dolby Digital, or a format that
DVD-Audio players are not required to support (DTS, MPEG 1 layer 2, or SDDS).
• Audio streams cannot switch seamlessly during playback.
• May not be in the same group as an AOTT or an AVTT/AOTT Title.

AVTT/AOTT Video-based Title in which the audio must be accompanied by the video:
• Plays on audio-only DVD-Audio players, as well as video-capable DVD-Audio
players and DVD-Video players.
• Only one allowed per group.
• Includes one or more video tracks (which can use up to nine angles), each defined
as a PTT.
• One audio stream must be LPCM.
• An optional second audio stream can be LPCM, Dolby Digital, or a format that
DVD-Audio players are not required to support (DTS, MPEG 1 layer 2, or SDDS).
• Audio streams cannot switch seamlessly during playback.
• In a group that also contains an AOTT, an AVTT/AOTT Title must be made up of a
single PTT (track), and it can only be used as either the first or last track in the
group.

DVD-Audio Creator automatically defines a video-based Title as an AVTT Title or an
AVTT/AOTT Title when the project is formatted in Format
• If a video-based Title includes an LPCM audio stream it is defined as an AVTT/AOTT Title.
• If no LPCM stream is present, it is defined as an AVTT Title.
Note: If you create a group that includes a combination of Titles that is not supported by
the DVD-Audio specification, an error alert will be generated when the project is formatted
in Format.

Combining Tracks in Groups
Based on the title types defined in Table 1, there are five cases of specification-compliant
groups that can be built in the Layout window:
• A group consisting of one or more audio tracks, each of which makes up all or part of an
AOTT Title (the Title itself is actually defined by Format later in the DVD-Audio Creator
production process). If more than one track is defined in a given Title, all tracks in that
Title must be used in the group.
• A group consisting of one or more video tracks, where all tracks are PTTs defined in the
same AVTT Title. If more than one track is used in the group, the tracks must be in the
same sequence as the PTTs defined in the AVTT Title.
AVTT/AOTT Video-based Title in which the audio must be accompanied by the video:
• Plays on audio-only DVD-Audio players, as well as video-capable DVD-Audio
players and DVD-Video players.
• Only one allowed per group.
• Includes one or more video tracks (which can use up to nine angles), each defined
as a PTT.
• One audio stream must be LPCM.
• An optional second audio stream can be LPCM, Dolby Digital, or a format that
DVD-Audio players are not required to support (DTS, MPEG 1 layer 2, or SDDS).
• Audio streams cannot switch seamlessly during playback.
• In a group that also contains an AOTT, an AVTT/AOTT Title must be made up of a
single PTT (track), and it can only be used as either the first or last track in the
group.