DVD-AR (Recordable DVD-Audio) Specifications

Exclusive: DVD-AR, recordable DVD-Audio, is on its way, the details of which have been exclusively revealed to HighFidelityReview by DVD Forum WG-4 chairman Bike H. Suzuki (JVC).

The DVD-AR format enables users to record, edit and replay a wide variety of audio content on writable discs. The main purpose of the format is to realise high-quality recording using Linear PCM and/or Packed PCM (using MLP), together with ‘long-time’ recording using any one of six lossy CODECs. In addition to audio contents, DVD-AR allows the user to store still pictures and text, just like DVD-Audio.

DVD-Audio Recording Specifications v0.9 were completed and approved by the Forum’s Steering Committee in late July. The v0.9 status of the document means that some small issues remain, but Bike explained the he hoped v1.0 would become a reality in early 2003, especially as the technical details of DVD-AR have already been finalised.

Bike H. Suzuki enthused:

“Now, we finally have DVD-Audio Recording specifications, which is surely a big enhancement to both DVD-Audio or DVD families.”

One significant issue remaining is that of copy-protection, however 4C, who developed the Content Protection for Pre-recorded Media (CPPM) scheme currently used for DVD-Audio are already busy creating a compatible system for DVD-AR and Bike feels that the IEEE-1394 interface (Firewire) will make the transmission of copy-protected digital data to and from recorder and players possible. This endorsement of IEEE-1394 comes on top of Texas Instruments’ announcement last week of their integrated cross-platform iceLynx Micro high-resolution interface, which uses IEEE-1394 technology at its core and the Forum’s own Firewire recommendations.

The DVD-Audio Recording Specifications v0.9 document will be published in mid October 2002, but a draft based upon an earlier version was made available to High Fidelity Review. We were assured that the version obtained and v0.9 are essentially identical and that all technical criteria are unchanged.

Details from the document itself:

Audio content is organised using the Audio Content model and is the equivalent of the group and track structure of DVD-Audio, albeit allowing for end-user modifications. The model is broken down as follows:

Original Track (ORG_TK)
    A logical unit of contents which are consecutively recorded, and corresponds to one song copied from CD/DVD disc, downloaded via a network, or recorded from microphone and/or broadcast.
Track Set
    The entire recorded contents of a disc, and consists of all Original Tracks.
    A specified segment of an Original Track.
User Defined Track (UD_TK)
    A pointer to an Original Track. Index and other information are inherited from the Original Track.
Play List
    A list of User Defined Tracks, and allows users to define any playback order by selecting from the content of Original Tracks.

The Over All content model contains still pictures and text related to a song and can be associated with that song as ASVU and Item Text (IT_TEXT). ASVU is a collection of ASVOB, which corresponds to a still picture whereas IT_TEXT is a collection of some text information, for example, the song name, artist name, lyrics and so on. One ORG_TK can refer one ASVU and one IT_TEXT.

DVD-AR is design to support both high-fidelity recording using loss-less formats and ‘long-time’ recording using any one of six lossy compression schemes. Discs can be created using both loss-less and lossy compression, although users need to consider the compatibility of created discs amongst their target playback audience. Both loss-less options (PCM and Packed PCM) are compatible with all DVD-Audio players as the PCM and PPCM encoders and decoders are mandatory for all DVD-Audio and DVD-AR machines, but the same cannot be said for all the lossy alternatives, of which only Dolby Digital and DTS are currently in widespread use.

The specifications do allow for discs to be created using a lossy compression scheme alone, PCM or PPCM is not required on the disc itself.

The table below shows all available audio formats, with the lossy options shaded grey.

Format Sample Rates Max. Channels Max. Data Rate
Linear PCM 44, 48, 88, 96, 176,
Six (44, 48, 88, 96kHz)
Two (176, 192kHz)
Packed PCM 44, 48, 88, 96, 176,
Six (44, 48, 88, 96kHz)
Two (176, 192kHz)
Dolby Digital 44, 48kHz Six 448kb/s
DTS 44, 48, 88, 96, 176,
Six (44, 48, 88, 96kHz)
Two (176, 192kHz)
MPEG-1/2 Layer II 44, 48kHz Six MPEG-1 384kb/s
MPEG-2 912kb/s
ATRAC-3 44, 48kHz Six 750kb/s
MP3PRO 44, 48kHz Two 320kb/s
MPEG-2 AAC   44, 48, 88, 96kHz Six 1,500kb/s

Playback time will depend on the audio format used, but PCM and PPCM should allow each disc to carry between six and eleven hours of material, whereas the use of a low-data rate lossy format could provide the ability to squeeze up to eighty hours onto a single disc.

Other points to note include the ability to input still images in JPEG format, and to associate these images with audio or EMD contents. The image presentation is carried out along the same lines as those for DVD-Audio; an ASVU of a song is pre-loaded to an ASVU buffer before a song is replayed and as a result, transitions between still pictures can be accomplished without the need for momentary mute periods. However, the transitions between images has been simplified compared to DVD-Audio, DVD-AD supports a browsable display timing mode, sequential and random order modes, a display duration mode with specific value and infinite together with cut, fade, wipe and dissolve effects.

All text information, the song name, artist name etc., is recorded in IT_TEXT for easy recoding, updating and maintaining. And AMGI, Play list, Track and Index can refer one IT_TEXT respectively.

DVD-AR is yet another welcome expansion of the DVD family of products, and one that can only help further the widespread acceptance of DVD-Audio. Although the ability to record vast amounts of audio in one or more lossy formats will probably the feature that appeals most to the masses, the inclusion of high-resolution record and playback capabilities will create a format that will also be of value to critical listeners and studio professionals alike. The promise of a digital IEEE-1394 interface is the icing on the cake.