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LaCie d2 Blu-ray Drive
User Manual
Helpful Technical Information
Page 25
ere are important factors to consider when record-
ing video, audio or data to CDs, DVDs or Blu-ray discs.
e DVD media specification provides for two physical
sizes: 4.7” (12cm) and 3.1” (8cm) (both are .47” (1.2cm)
thick). Blu-ray and DVD discs are single-sided and can
have one (SL) or two (DL) layers of data.
e amount of data or video that a disc can hold
are dependent upon factors such as the amount of au-
dio and the degree of compression of the data, video
or audio. For example, a double-layer BD-R will store
just over 4 hours of HD video using MPEG2, but it
is possible to store up to 20 hours of broadcast quality
standard definition video.
When media companies reference the amount
of data that a disc can hold, they represent the total
amount in terms of gigabytes (GB), or a billion bytes
(1000 x 1000 x 1000 bytes). is number, though, is not
the way in which a computer addresses the data; to a
computer the value is binary and larger than a billion
bytes – 1,073,741,824 (1024 x 1024 x 1024 bytes).
4.3. About BD/DVD/CD available capacity
4.4. About compression standards
Most of the Blu-ray Video material and all the
DVD-Video materials are compressed using MPEG2
codec. e acronym MPEG stands for Moving Picture
Expert Group, which worked to generate compression
specifications under ISO.
What is commonly referred to as “MPEG video” ac-
tually consists at the present time of three finalized stan-
dards, MPEG1, MPEG2, MPEG4 which was finalized
in 1998 for Very Low Bitrate Audio-Visual Coding.
HD Video, with full-motion video and multi-chan-
nel sound (multi-lingual soundtracks, surround sound,
etc.), is a data-hungry application. MPEG2 compres-
sion allows you to fit a full-length feature film in HD,
plus bonus material, on just one disc.
MPEG4 AVC (H.264) and VC-1 are two other HD
video compression standards which can match the best
possible MPEG2 quality at up to half the data rate. But
they are not not much used by the professional video
industry yet.
Indication of bit rates for HD Video:
MPEG2 = 21Mbits/s
MPEG4 (H.264) = 8Mbits/s
VC-1(WMV9) = 8 Mbits/s
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