Optical Disc Formats for Audio Reproduction and Recording 115130.8.3 Meridian Lossless Packing (MLP)
Meridian lossless packing (MLP) is an audio coding
algorithm used to achieve lossless data compression. It
reduces average and peak audio data rates and hence
reduces storage capacity requirements. MLP packs
audio data more efficiently, reducing file size without
altering the contents. MLP offers other specific
enhancements over PCM; whereas a PCM signal can be
subtly altered by generation loss, transmission errors
and other causes as it passes through a production chain,
MLP can ensure that the output signal is exactly the
same as the input signal by checking the MLP-coded
file and confirming its bit accuracy. The compression
achieved by MLP depends on the music being coded.
Very approximately, it gives a 1.85:1 compression ratio;
thus reducing the bit rate by almost 50%, doubling play-
ing time with no loss of audio quality. For example,
without compression, 96 kHz/24 bit audio requires
2.304 Mbps per channel. Thus a six channel recording
would require 13.824 Mbps, exceeding DVD-Audio’s
9.6 MHz maximum bit rate; thus LPCM cannot be used
in the configuration. In contrast, MLP allows six-chan-
nel 96 kHz/24-bit recordings; it may achieve bandwidth
reduction of 38% to 52%, reducing bandwidth to 6.6 to
8.6 Mbps, allowing a playing time of 73 to 80 minutes
on a DVD-5 disc. In the two-channel stereo mode of
192 kHz/24-bit, MLP provides a playing time of about
117 minutes, versus a playing time of 74 minutes for
LPCM coding.
Unlike lossy perceptual coding methods, MLP
preserves bit-for-bit content of the audio signal. MLP
provides less compression than lossy methods, the
degree of compression depends on the audio signal
content, and the output bit rate can continually vary
according to signal conditions; however, a fixed data
rate mode is provided. MLP is a mandatory coding
option. Thus, all DVD-Audio players must support
MLP decoding, but use of MLP on discs is optional for
content providers. MLP may be used on a track-by-track
basis. All of the DVD-Audio sampling frequencies are
supported by MLP and quantization may be selected for
16 to 24 bits in 1-bit steps. MLP can code both stereo
and multichannel signals simultaneously.
30.9 Other DVD Formats
The DVD-Video format is defined in Book B and
DVD-Audio is defined in Book C. However, the DVD
family also includes DVD-ROM (Book A), DVD-R
(Book D), DVD-RAM (Book E), and DVD-RW (Book
F). Books A, B, and C use the UDF Bridge file format
while Books D, E, and F use the UDF format. The
DVD-ROM, DVD-R, DVD-RAM, and DVD-RW for-
mats are used primarily as computer peripherals or in
professional authoring environments.
All DVDs are essentially DVD-ROMs, and all
DVDs use the basic UDF format. Some DVD applica-
tions, such as DVD-Video, place specialized material in
a specific place such as the DVD-Video zone. Content
contained in the DVD-Other zone may be quite varied.
DVD-ROM uses that provision for nonspecific storage,
acting as a large capacity bit bucket formatted with
UDF. DVD-ROM are playback-only media used to
store data, software, games, etc. With appropriate soft-
ware, DVD-ROM drives can play DVD-Video and
DVD-Audio.
The DVD-R format offers write-once capability to
permanently record data. DVD-Rs use a CLV wobbled
pregroove to generate a carrier signal used for motor
control, tracking and focus. DVD-Rs use pits and lands
(known as land prepits) molded into land areas between
grooves to encode the time address and other prere-
corded signals. A cyanine organic dye recording layer
may be used, with a 635 or 650 nm laser. The reading
laser tracks the pregroove, but the light shines on the
prepits peripherally to create a secondary signal that is
extracted from the main signal. Discs can use the same
reference velocity and track pitch as molded discs to
achieve the same unformatted storage capacity. There
are two parts to the DVD-R specification: DVD-R
General and DVD-R Authoring; both yield discs play-
able on DVD-Video players.
DVD-R recorders perform an optimum power cali-
bration (OPC) procedure to determine the correct laser
writing power for particular discs, using a power cali-
bration area (PCA) on discs to test laser writing power.
A recording management area (RMA) saves calibration
information, disc contents, and recording locations and
remaining capacity information, recorder and disc iden-
tifiers for copy protection. The remainder of the disc
comprises the information area containing the lead-in,
data recordable area, and lead-out. The lead-in contains
information on disc format, specification version, phys-
ical size and structure, minimum readout rate, recording
density, and pointers to the location of the data record-
able area where user data is recorded. The lead-out
marks the end of the recording area. Both sequential
(disc-at-once) and incremental writing can be
performed. Once recorded, discs can potentially be
played in DVD-ROM, DVD-Video, and DVD-Audio
players. DVD+R is another write-once format using a
dye recording layer and CLV rotation. Capacities of 4.7
and 8.5 (DL) Gbytes are available. DVD+Rs are gener-