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A sound idea
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06/06/2008
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DVD and related optical media have raised the bar for high end audio/video systems and the key to higher audio quality lies in analogue and mixed signal circuitry.
At 4.7Gbyte, a dvd provides around seven times the raw data storage capacity of an audio cd and the upward trend continues with HD-DVD and Blu-Ray. Meanwhile, lossy and lossless compression algorithms have emerged to make more efficient use of the physical media.
This extra data capacity not only prolongs playback time, but also allows audio to be recorded more accurately. New formats take advantage of this to provide multichannel surround sound, as well as higher sampling rates and data resolutions in the decoded audio streams.
Whereas a cd player outputs two channels sampled at 44.1kHz with a resolution of 16bit, DVD-Audio disks carry up to six channels at 24bit/sample and support sampling rates up to 192kHz. On the other hand, Mpeg4 encoded video dvds use AAC compression for the audio information, with sampling rates up to 96kHz and sample resolution dependent on the AAC decoder implementation. But what do these numbers actually mean for sound quality?
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Author
Duncan Macadie
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