Introduction Coherent
Acoustics is a digital audio compression algorithm designed for both professional
and consumer applications. The algorithm is highly flexible, operating over multiple
channels of audio, at sampling rates up to 192 kHz, with up to 24-bit resolution.
This article outlines the overall design objectives of the algorithm, and describes
the principal coding strategies employed to meet these goals. Specific functional
components of the encoding and decoding algorithms are outlined in more detail,
and the feature set of the coding system is summarized. Finally, the objective
performance of the algorithm is illustrated using some simple test signals.
Global
design objectives The DTS Coherent Acoustics audio compression algorithm
was designed with the primary objective of significantly improving the quality
of audio reproduction in the home, beyond that of conventional compact discs.
Consumers would benefit from more accurate sound recordings that utilized a wider
range of audiofrequencies, played back through more loudspeakers. The goal was
to provide reproduction technology to the consumer that was as good as that found
in professional music studios.
Secondarily,
it was intended that the technology be used in a wide range of applications, in
both the professional and consumer arenas, and that the consumer decoder be computationally
simple and yet resistant to obsolescence. This required that the algorithm host
a wide range of ancillary features suitable for home and studio use, and operate
flexibly within a coding structure based around a complex intelligent encoder
and a simple passive decoder.
Improving
audio reproduction in the home The key to delivering dramatic improvements
in reproduction quality is the greater audio recording efficiency realizable through
modern digital audio data-reduction techniques. In Coherent Acoustics this gain
in efficiency has been used directly to improve the precision of the recorded
audio. The importance of the concept warrants a more detailed explanation, which
is given below. Other coding systems have used compression in a more traditional
way, by simply attempting to minimize the data rate of the coded audio.
While
this approach can lower the cost of storing or transmitting the digital audio,
it does not seek to improve quality. This is in contrast to Coherent Acoustics,
which uses compression techniques primarily to maximize the quality of the audio
delivered to the consumer.
