Lancaster, PA (December 9, 2005)–Linear Acoustic, in cooperation with Omneon Video Networks and Miranda Technologies, recently hosted the first in a series of educational seminars for broadcasters planning to make the transition from SD to HDTV broadcasting. Entitled “HDTV: Making the Transition,” the first seminar was held during October in London for representatives of the British Broadcasting Corporation, BSkyB, Ascent Media Services and other organizations. It was followed last month with seminars in Montreal and Atlanta.
Linear Acoustic president Tim Carroll addressing the “HDTV: Making the Transition” seminar”Many broadcasters are still confused about the choices for generating, distributing and processing high-definition material, specifically multichannel audio,” considered Linear Acoustic president Tim Carroll, an acknowledged expert in surround sound technologies. “Linear Acoustic is a leader in the development of new systems for cost-effective contribution, distribution and processing of multichannel audio material.”
The seminar program comprises a series of spotlight presentations on such
. The Inevitability of HDTV – a look at the drivers for HD from consumers
. Fundamentals of Video and Audio Formats for HDTV.
. HD Building Blocks – looking at distribution, routing, conversion,
editing, servers and master control.
. HD Case Studies – tales from the converted by senior broadcasters.
The seminars are non-promotional, and are being presented by senior engineers from Linear Acoustic, Omneon and Miranda, as well as by leading broadcasters. Technology demonstrations associated with core themes also are being offered at the end of each seminar. (A modest attendance fee is charged to cover material and refreshment costs.)
Tim Carroll’s presentation, “Audio for HD: From Playout to Delivery,” explored Emission Technologies – Audio from broadcaster to consumer; Contribution and Distribution Technologies – Audio to the network and local broadcaster; and Connecting it all Together – Monitoring, master control and other issues.
“The two leading multichannel audio emission technologies are AC-3 or Dolby Digital, and DTS Coherent Acoustics,” Carroll acknowledged. “AC-3 carries from one to 5.1 channels of audio at data rates between 56 and 640 kbps, while DTS Coherent Acoustics – also part of the DVB standard – offers sample rates from 8 to 96 kHz, and supports up to 32 channels at 24-192 kbps/channel. Both formats are compatible with millions of consumer playback systems.
“While video has been the major focus for codec improvement, audio bandwidth requirements also must be considered carefully. We are not just considering 5.1-surround sound playback but, in international markets, multi-language/multi-dialect and multi-program; versions for the visually impaired also are important. And new audio codecs such as AAC Plus bring more to the party via higher efficiency, improved quality at today’s data rates, enhanced channel capacity and high efficiency at 8-160 kbps/channel.”
Key Metadata parameters are supported by all systems. “Dialog Level–DialNorm–controls a 1 dB/step attenuator in all consumer decoders, and is used to match program-to-program loudness,” Carroll continued. “Dynamic Range Control value is generated within the encoder, and selectively applied by consumer decoders. Experience has shown that most loudness shifts are due to metadata differences between network and local programs; very seldom does the local station create the proper custom metadata. Dynamics Processing can help match local audio to default metadata values, while Upmixing helps mask two-channel/5.1-channel switching issues.”
“The lines are starting to blur between Contribution, Distribution and Emission,” Carroll stressed. “PCM is again gaining popularity, and embedded audio can support many channels, with Metadata inserted into V-ANC space to ensure video, audio and metadata remain in lock-step sync. Distribution still requires mezzanine compression, although 4:1 codecs may not be sufficient to provide multiple programs with surround sound. There are new technologies that allow emission coders to act more like distribution coders; with splicing and other techniques, re-coding is minimized or eliminated.”
Current Linear Acoustic products include:
. StreamStacker Multichannel Audio Distribution System, which comprises the Model LA-5421 StreamStacker Audio Bitstream Multiplexer and Model LA-5124 StreamStacker De-Multiplexer/AC-3 Splicer.
. Model LA-5124 with AutoNorm Automatic Dialog Normalization System.
. OCTiMAX 5.1 Digital Television Audio Processor.
. UpMAX 2251 5.1 Channel Surround-Field Synthesizer.
. AEROMAX-HDFM Multichannel Radio Processor.
Linear Acoustic, Inc.