Telos Zephyr, Руководство пользователя

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Section 7 AUDIO CODING PRINCIPLES
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Pre- Simultaneous- Post- Masking
Masking effects in the time domain. Masking occurs both
before and after the masking signal.
ISO/MPEG LAYER III
MPEG Layer III is the most powerful coding method available in the Zephyr, and we
particularly like it because it is perfectly matched to the bitrates available on ISDN BRI
lines.
It offers:
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15 or 20kHz mono or stereo audio bandwidth.
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Full- fidelity mono on a single 56/64kbps channel.
•
CD- quality stereo on a single ISDN Telco circuit.
•
Affordable, transparent, audio transmission for AM/FM radio or television audio.
After extensive testing by broadcasting organizations around the world under the
direction of the CCIR, it has been designated as the most powerful of the three audio
coding systems standardized in ISO/MPEG IS- 11172. It is specifically recommended for
56 and 64 kbps channels.
IMPORTANT!
Due to a perceptual coder’s reliance on precise principles of
human perception, audio to be coded should not be processed
with any non-linear dynamics-processing such as clipping,
multi-band compression or limiting. Wideband compression or
AGC is acceptable and may be desirable if a consistent level
cannot otherwise be achieved.
The same is true to audio which has been decoded after
passing through a perceptual coding cycle, but to much lesser
degree.
For more information contact Telos Systems customer support
for a copy of a paper delivered at the AES by Frank Foti on
this topic.