多媒体信号处理Revision

Revision Lecture
Copyright 2008-2015, Christian Ritz, University of Wห้องสมุดไป่ตู้llongong
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Lecture 5
• Noise and it’s affects on perceptual speech quality
– Different types of noise have different spectral characteristics – Affects both speech listening quality and intelligibility
• Speech enhancement algorithms
– Simplest is the spectral subtraction algorithm – Over-subtraction is used to control musical noise
• Measuring the performance of speech enhancement systems
to be created
Revision Lecture
Copyright 2008-2015, Christian Ritz, University of Wollongong
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Lecture 6
• The human auditory system • CD Audio • MPEG Audio coding
– Fixed length binary code – Huffman code – Entropy rate
Revision Lecture
Copyright 2008-2015, Christian Ritz, University of Wollongong
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Lecture 3
• Speech signals:
Copyright 2008-2015, Christian Ritz, University of Wollongong
– Motivation for transform coding – One dimensional versus two dimensional transforms – Discrete Cosine Transform (DCT) for image coding
Revision Lecture
– Different standards distinguished by the methods used to represent the excitation
• Excitation representations
– Parametric – Analysis-by-Synthesis – Multipulse Excitation – CELP
– Uniform, non-uniform, adaptive
Revision Lecture
Copyright 2008-2015, Christian Ritz, University of Wollongong
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Lecture 2
• Define Compression • Describe lossless and lossy compression • Lossless Compression
ECTE401 Multimedia Signal Processing
Revision Lecture
Revision Lecture
Copyright 2008-2015, Christian Ritz, University of Wollongong
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Lecture 1
• Described multimedia and multimedia signals • Time and frequency • Analog and digital • Sampling • Quantisation
– Voiced and unvoiced – Short term correlation
• Linear prediction
– Removes short term correlation – Models the vocal tract
• Long term prediction
– Removes the long term (pitch) information from the residual signal
– MPEG-1 Layer III (MP3)‫‏‬ – MPEG-2 – MPEG-4
• Dolby Digital – AC3 • Multichannel audio coding
– MPEG Surround
Revision Lecture
Copyright 2008-2015, Christian Ritz, University of Wollongong
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Lecture 7
• Introduction to image and video coding
– Image Representation – Digital images – Colour Perception – Video representation
• Transform coding of images
– Subjective and objective measures
• Brief introduction to microphones
– Different types have different polar responses – Microphone arrays allow customised polar responses
Revision Lecture
Copyright 2008-2015, Christian Ritz, University of Wollongong
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Lecture 4
• Introduction to speech coding standards
– Most low bit rate coders based on Linear Prediction