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Project Proposal Audio Compression Variants. Doris Jean ELEN EE6820 djean95@yahoo.com. Outline. Overview of Data Compression Project Scope Project Goal Closing Thoughts. Data Compression Fundamentals. Needed to accommodate memory constraints in digital communication systems.
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Project ProposalAudio Compression Variants Doris JeanELEN EE6820djean95@yahoo.com
Outline • Overview of Data Compression • Project Scope • Project Goal • Closing Thoughts
Data Compression Fundamentals • Needed to accommodate memory constraints in digital communication systems. • Two types of compression techniques; • Lossless Used for applications that require the exact replica of the original data after decompression. • Lossy Used for applications that don’t require decompressed data to be restored exactly as the original. • Compression efficiency is measured by the Compression Ratios. • Lossy techniques have greater ratios than Lossless
Data Compression Fundamentals (Cont’d) • Three categories of compression techniques: • Entropy coding Uses lossless compression techniques • Source Coding • Uses lossy technique • Include Sub-band coding, Sub-sampling, Bit Positioning, DCT, FFT, DM and DPCM as compression algorithms Hybrid Coding • Uses a combination of Entropy and Source coding • Used for MPEG-1 audio compression algorithms
Project Scope • MPEG-1 Audio • Audio compression algorithm that is based on sub-band coding • Widely used in digital audio systems • MPEG-1 has three layers: layers I, II, III • These layers differ by their signal reconstruction accuracy and by the computation complexity involved in the psychoacoustic model. • MPEG 1 Layer III, also called MP3, has better audio signal reconstructions than Layer I or II. • However its computation complexity is more involved in layer III and it requires more processing time.
Project Scope (Cont’d) • MPEG-1 audio compression method has two mean drawbacks: • Has lossy characteristics at high compression ratios • Computations involved in the psychoacoustic model part of the compression process causes time delay • My project will focus on the MPEG-1 computations drawbacks
Input Audio Signal Frequency Division Psychoacoustic Model Quantization Controls Entropy Encoding (Subband Coding) Compressed Audio Signal Project Scope (Cont’d) MPEG-1 Compression Process
Project Goal • Investigate the time delay involved in MPEG-1 Audio layer III compression algorithms • Compare the delay to that of MPEG-1 layer II • Propose design modifications to reduce the delay in Layer III algorithms • Value added • Achieving time delay reduction in MPEG-1 Audio compression algorithms
Closing Thoughts • I would like to acquire these two IEEE articles in reference to my continued effort on the project. • * MPEG Digital Audio Coding, P. Noll, pp. 59-81. • * MPEG Digital Video-Coding Standards, T. Sikora, pp 82-100 • I look forward to your comments and feedback. -Thank you