Optical Disc Formats for Audio Reproduction and Recording 1147ing system software. However, a DVD-Video or -Audio
player supports only UDF and not ISO-9660.
In read-only DVD formats, data is stored in files
within directories. DVD data is placed on a disc in
physical sectors that run continuously without gap from
the lead-in to the lead-out area. A DVD data sector
comprises 2064 bytes, with 2048 bytes of main data and
16 header bytes; the latter comprises 4 bytes of identifi-
cation (ID), 8 bytes of other data, and 4 bytes of error-
detection code (EDC) data. The 4 bytes of identification
data (ID) contain 1 byte of sector information and 3
bytes of sector number. A sync code is added to the
head of every 91 bytes in the recording sector. This
forms a physical sector. In all, 52 bytes of sync code is
added. The 2048 bytes of user data is thus increased to
2418 bytes.
A Reed-Solomon Product Code (RS-PC) uses a
combination of two Reed-Solomon codes (C1 and C2)
as a product code. It differs from the CD’s CIRC code.
The two C1 and C2 product codes are (208,192) and
(182,172) in length. Error correction is more chal-
lenging on a DVD because the pit size is smaller. In
addition, because of the thin substrates, surface defects
can more readily obscure the data surface. However,
RS-PC is more powerful than the double error correc-
tion used in the CD-ROM format and provides
improved error protection. RS-PC is also more efficient
than CIRC in terms of overhead. In the DVD format, all
disc types use the same level of error correction.
Read-only DVDs use EFMPlus modulation. It is an
8/16 RLL code and is similar to the EFM code used in
CDs; for example, it uses the same minimum (2) and
maximum (10) run length and represents logical 1
channel bits as pit/land or land/pit transitions and
logical 0 channel bits as no transition. EFMPlus
provides a 6% increase in user storage capacity
compared to EFM because its coding is more efficient
than EFM. Whereas EFM uses merging bits and a single
lookup table and simple concatenation rules to suppress
low-frequency content, EFMPlus does not require
merging bits and uses a more sophisticated look-up
method. The EFMPlus encoder defines four look-up
tables each with 351 possible source words. In practice,
the source codebook size is 344; seven possible words
are discarded to allow for a unique 26-bit sync word. Of
these, 256 words are used to code input data. The 88
surplus words are used as alternative channel represen-
tations to minimize the running digital sum value (DSV)
and thus control low-frequency content.
In a DVD player, data passes through a buffer and is
evaluated by a navigator/splitter that separates the bit
stream into video, subpicture, audio, and navigational
information. The video, subpicture, and audio data is
decoded; for example, MPEG-2 video data is decoded
as is Dolby Digital audio data. This can occur in a dedi-
cated hardware chip or with software via a computer
CPU. Navigational information is used by a controller
for the user interface, while audio and video data is sent
to the appropriate outputs.30.7 DVD-VideoThe DVD-Video format provides storage and playback
of motion pictures or concert videos with multichannel
soundtracks. The format was designed to provide the
following: at least 133 minutes of digital video,
approaching D1 broadcast picture quality, stereo or mul-
tichannel digital audio, multiple aspect ratios, up to 8
language soundtracks, up to 32 subtitles, parental con-
trol options, and copy protection.
In the DVD-Video format, data in a video disc is
organized using the UDF Bridge file format. A
DVD-Video zone and DVD-Other zone are defined
under a root directory. In the DVD-Video zone, the
VIDEO_TS directory (folder) contains menu and
presentation data (video, audio, etc.). A Video Manager
defines file types and organization of both video and
audio data, and Video Title Set (VTS) subdirectories
contain video and audio data files (such as MPEG-2
video and Dolby Digital audio). One Video Manager
can contain up to 99 VTS subdirectories. Other
computer data may be contained in the DVD-Other
zone; this data may be used by DVD-ROM drives, and
is ignored by DVD-Video players.
A DVD-Video VAN disc contains video-audio navi-
gation data in a hybrid video-audio disc. VAN discs are
video discs but they contain audio information that can
be played on DVD-Audio players. Audio data is
contained in an Audio Title Set, and video data in a
Video Title Set. The Audio Manager and Video
manager define file types and organize both audio and
video data; both menu and program data is included.
Using Link Info, a DVD-Audio player can play audio
components of video contents.
The DVD-Video standard uses the MPEG-2 data
compression algorithm to encode its video program. It
employs the MPEG-2 Main Profile at Main Level
protocol, also known as MP@ML. This is an interme-
diate level and below the high level sometimes used for
DTV. However, MP@ML yields a high-quality picture
that equals that of the professional CCIR-601 standard.
The MPEG-2 video compression algorithm analyzes the
video signal. Image data that is deemed redundant, not
perceived, or marginally perceived is not coded or