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3. Sound coding
Looking back at the development of MPEG digital audio standards since 1988, MPEG-4 Audio represents the 4th generation.
In 1992, MPEG-1 Audio was standardized. It defines the coding-compression of one or two high-quality audio channels, sampled at 32, 44.1 or 48 kHz. It has a choice of 3 configurations, or layers, depending on the requirements of different applications. Layer 2 (total bitrate 32-384 kbit/s, transparency 128 kbit/s per channel) and layer 3 (MP3; total bitrate 32-320 kbit/s, transparency 96 kbit/s per channel) are the most widely used.
In 1994, MPEG-1 Audio was complemented by MPEG-2 Audio, offering extensions with reduced sampling frequencies (16, 22.05 and 24 kHz) and a multichannel (5) stereo compatible mode (backward compatible,...
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Sound coding
Conclusion
Bibliography
References
Organizations
- (1) - - IETF (Internet Engineering Task Force) http://www.ietf.org/
- (2) - - ISO (International Organization for Standardization)
Standards and norms
Objects, Coding tools, MPEG-4 Video profiles
MPEG-4 defines a set of object types, each characterized by specific visual information and an underlying set of coding tools.
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