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Small on data size. Big on sound. We live in a society that desires maximum results with minimum costs. In audio-entertainment technology, it seems that consumers expect a lot- fast music downloads, DVD surround sound that doesn't take up a huge chunk of data, and high-definition, high fidelity sound. Enter the Advanced Audio Zip(AAZ). The invention of Rongshan Yu, Susanto Rahardja and Xiao Lin, researchers from the Institute for Infocomm Research, AAZ offers effective technology combining scalability and interchangeability. This replaces the current solutions for Lossy and Lossless audio compression. It is anticipated that AAZ will be the audio codec of the next generation - software that compresses data to a particular coding scheme, then decompresses it during playback. The purpose of Lossy compression techniques is to eliminate some audio information, in order to achieve high compression ratios. Lossy techniques preserve the essence of sound but do not restore the precise bits- the higher the compression, the lower the sound quality. Ordinary Lossless techniques do restore all original audio data after compression, without loss or distortion. However, though this technology is effective for archiving purposes, only limited compression ratios between 1.5 and 3.0 are achieved. In this respect, AAZ's Lossless technology trumps current Lossless techniques, as it allows users to vary the quality of digital sound by compressing the sound signal by 1.5-40 times. This depends on its 'core', the Advanced Audio Coding (AAC), or MPEG4 Audio codec, for which AAZ is backward-compatible. The core, set at 32kbps, gives a compression of about 40 times. However, when set at 64kbps, the compression range is 1.5-20 times. This feature is extremely useful for applications where requirements are of a variable quality (for example, in an audio-streaming application with time-varying channel conditions). In response to a Call for Proposal on MPEG-4 Lossless Audio Coding, AAZ technology was submitted and evaluated by independent testers for MPEG. The AAZ system outperforms all other systems and was shown to be the best in terms of the mean Lossless compression ratio at any word length, and all sampling rates for all sequences in the test set ('word length' is the number of bit resolutions, where the higher value represents better resolution). Researchers performed tests with 16-bit, 20-bit and 24-bit resolutions, with the average Lossless compression ratio taken as the best result for the three word lengths. With its positive showing, AAZ was adopted as the Reference Model for scalable Lossless coding for MPEG systems in July 2003.
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