Optical Disc Formats for Audio Reproduction and Recording 1153(AES) to encrypt contents using one or more title keys.
Content providers can revoke the decryption keys in
individual players. Region coding is not used in the HD
DVD format; any title can be played in any player. HD
DVD uses the Microsoft HDi Interactive Format plat-
form for interactive content on discs. HDi is based on
existing protocols such as HTML, XML, CSS, SMIL,
and JavaScript.
Alternative formats have been developed. The 3×
DVD format uses a red laser; it yields approximately
three times the storage capacity of DVD-Video; this
format can hold high-definition content, but with
shorter playing times. The HD REC format also stores
high-definition content using a red laser and
H.264/MPEG-4 AVC compression. The Combo hybrid
disc is a dual-side disc (with up to two layers each) with
a HD DVD layer and a DVD layer. A twin hybrid disc
is a single-side disc with up to three layers, with either
HD DVD or DVD content. Single-layer HD DVD-R
and HD DVD-RW hold 15 Gbytes and dual-layer discs
hold 30 GB. A single-layer HD DVD-RAM holds
20 GB. An experimental ten-layer disc would increase
HD DVD storage capacity to 150 GB.30.11 Blu-ray Disc FormatThe Blu-ray disc system (also called BD) uses a 405 nm
blue-violet laser and numerical aperture (NA) of 0.85 to
achieve high storage capacity. Storage capacity is
25 Gbytes on a single-side, single-layer 12 cm disc. A
single-side, dual-layer disc can hold 50 GB, or 9 hours
of high-definition video. Track pitch is 0.32μm, and the
shortest pit length is 0.15μm. The structure of the BD is
shown in Fig. 30-19. The data layer is built on a 1.1 mm
thick substrate and covered by a 0.1 mm spin-coated
cover layer placed directly over the data layer and an
optional top protection layer. The single-speed bit rate is
36 Mbps, the double-speed rate is 72 Mbps, the four
times rate is 144 Mbps, and the six times rate is
216 Mbps. BD movies have a maximum data bit rate of
54 Mbps (1.5×); of this, the maximum video bit rate is
40 Mbps. A Blu-ray drive must operate at 1.5× speed to
play BD movies. BD supports the ISO 9660 and UDF
optical disc file formats. Although backward compati-
bility is possible, it is not required that BD players must
also play CD and DVD-Video. BD drives are found in
PS3 players and are available for computer applications.
The BD-ROM data layer is placed on the outer disc
surface. The optical path is through a thin polymer layer
that provides scratch resistance, not the substrate. Thus
the substrate’s optical characteristics are not crit-
ical—for example, birefringence is not a concern.
Because the objective lens is close to the data layer,
optical aberration caused by disc tilt is limited. A 17PP
modulation code is used, and a picket code with two
Reed-Solomon codes is used for error correction.
The BD-ROM standard defines four player profiles.
They describe functionality such as built-in persistent
memory, local storage capability, secondary video
decoder (for PiP), secondary audio decoder (for
commentary and interactive content), virtual file
system, and Internet connection capability. The four
profiles are known as BD-Video (Grace Period
Profile—Profile 1.0), Bonus View (Final Standard
Profile—Profile 1.1), BD-Live (Profile 2.0), and BD
Audio-Only (Profile 3.0).
The mandatory video codecs for BD-ROM players
are VC-1 (SMPTE 421M), MPEG-4 H.264 Advanced
Video Codec (AVC), and MPEG-2. The VC-1 and
H.264 codecs are preferred; compared to MPEG-2, they
provide greater compression and hence longer content
run times, with similar quality. The BD format supports
a wide range of video resolutions ranging from low to
high resolution. The MPEG-2 transport stream is
compatible with broadcast DTV.
Mandatory audio codecs for BD-ROM players are
Dolby Digital, DTS, and linear uncompressed PCM
(LPCM). A BD can hold up to up to eight channels of
uncompressed LPCM audio. Optional audio codecs
include Dolby Digital Plus, Dolby TrueHD (using
MLP), DTS-HD Master Audio, and DTS-HD High
Resolution Audio. Primary soundtracks must use a
mandatory codec while secondary soundtracks can use
either a mandatory or optional codec.
BD optionally allows use of the advanced access
content system (AACS) for digital rights management,
copy protection and content distribution control. AACS
uses the advanced encryption standard (AES) to encrypt
contents using one or more title keys. Title keys are
formed from a media key, and the media’s unique
volume ID embedded on every disc. A broadcastFigure 30-19. Blu-ray discs use a 1.1 mm substrate and a
0.1 mm protective layer. A single-layer disc is shown, but
dual-layer discs can be used.1.2 mmSurface velocity = 5.9 m/sNA = 0.85L = 405 mm1.1 mm0.1 mm 0.1 mm