reported
by: Dr. Roland K C Tan
Student Cousellor &
WebMaster (Term 2000/2001)
On Friday, 3rd November 2000,
10 members and 14 guests of the AES Singapore Section gathered
at the ACE Daikin Auditorium to attend a seminar on “Dolby E in
Broadcasting” by Mr. Paul Davies, a Senior Broadcast
Applications Engineer from Dolby Laboratories based in Wootton Bassett,
England. Despite the wet weather forecast and heavy traffic report, many of
the attendees had managed to arrive at the venue just in time for the talk
by about 7.45pm. This is the section’s fourth event for the Term
2000/2001.
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After a brief introduction by the current Section Chairman, Mr.
Robert Soo, the speaker began by first presenting an overview of the
format of Dolby E coding that consists of the Dolby E multi-channel
audio plus the consumer and professional metadata. And including the
guard bands, each Dolby E frame has a time of 40msec which matches the
video frame exactly. This solves the major problem in trying to use
existing MPEG or Dolby Digital audio coding in the professional video
environment since a Dolby Digital has a frame time of exactly 32 msec at
48kHz sample rate. Existing editing and switching practices may be
performed on the encoded Dolby E bitstream without causing mutes or
other audible distortions when the bitstream is decoded back to baseband
PCM. |
Mr. Paul Davies
presenting his talk on Dolby E in Broadcasting at the ACE Daikin
Auditorium - photograph by Mr. Michael Teh. |
Paul stressed that Dolby E
coding technology was designed specifically for distribution applications
and therefore, it would never reach the consumers. It is intended to
facilitate the transition from 2- to 5.1-channel audio without requiring
complete replacement of the existing infrastructure. The Dolby E-type audio
coding technology will allow much of the existing 2-channel linear PCM
digital audio infrastructure, such as the VTR, routers, or embedders, to
carry mulitchannel audio. A single Dolby E bitstream will mimic a 2-channel
24-, 20-, or 16-bits @ 48 kHz PCM audio signal and can carry up to 8
discrete audio channels.
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Dolby had envisioned that the future infrastructure would utilize linear
PCM audio in production and post-production. Certain program elements,
such as those arriving via satellite or telco links, however, may pass
through a small number of generations of professional quality audio
coding such as Dolby E. Any audio processing manipulation, including the
generation of the audio metadata that affects the |
Mr. Paul Davies
(centre) mingling with his audience after the Q&A session -
photograph by Mr. Michael Teh. |
final reproduction at the Dolby
Digital decoder, should be done in post-production where the subjective
effects can be properly monitored and evaluated. The remainder of the
distribution and emission signal path should, ideally, transparently deliver
the audio experience designed in post-production to the home listener.
Distribution begins at the output
of the post-production process, where the audio will be encoded into the
Dolby E format. The signal can remain in the Dolby E format through tape
generations, satellite links, signal routing, and content editing. When the
audio signal must undergo additional processing, such as cross-fads to
|
Mr. Paul Davies
(left) receiving a speaker plaque from the Section Chairman, Mr. Robert
Soo - photograph by Mr. Michael Teh. |
other programs,
the signal will be decoded to baseband linear PCM and then re-encoded
into Dolby E.
An explanation on how the
Dolby E system can provide sufficient audio quality in order to survive
a large number of concatenated encode/decode generations was also
briefly discussed. Paul described briefly about the perceptual
coding technique, which basically utilises the psychoacoustic
characteristics of the human hearing such as the masking effect. This
was followed by some discussion on the metadata parameters, among many
others. At the end of the distribution chain, the Dolby E encoded signal
will be converted to the Dolby Digital (AC-3) format for final delivery
to the consumer at the low emission data rate. |
Paul finished his talk in
about an hour at around 8.45pm. Members of the audience raised several
interesting questions during the question-and-answer session that followed.
One of the questions concerned was whether or not Dolby E can be applied in
radio broadcast.
|
Mr. Paul Davies
(tallest man standing in the centre), with 10 members and 14 guests
after his talk at the ACE Daikin Auditorium -
photograph by Mr. Michael Teh. |
The AES Singapore Section would
like to express their sincere thanks to Mr. Harry Chua, General
Manager of ACE Daikin (Singapore) Pte Ltd, for allowing the seminar to be
conducted at their premises. And also to Mr. Chan Kheng Wah, Dolby
Labs Business Liaison for S.E. Asia, for assisting in the co-ordinating of
this event. |
