Chapter 7, DIGITAL AUDIO COMPRESSION Video Solutions, Multimedia Signals and Systems

02:00

Problem 1

What are the main principles of the audio compression techniques?

Mirza Aslam Beig

Numerade Educator

Problem 2

You are quantizing an analog audio signal. How much quantization noise (in $d B$ ) do you expect if you use $8,12,16$ and 24 bits/sample/channel?

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01:31

Problem 3

Calculate the probability density function and entropy of the audio signal belll.wav provided in the $C D$. What compression factor can be achieved using the entropy coding method?

Alexander Clippinger

Numerade Educator

00:52

Problem 4

What is the principle of DPCM coding method?

Lottie Adams

Numerade Educator

The autocorrelation matrix of an audio signal is given by
$$
\left[\begin{array}{ccc}
1 & 0.9 & 0.8 \\
0.9 & 1 & 0.9 \\
0.8 & 0.9 & 1
\end{array}\right]
$$
Calculate the optimal first and second order predictors. Can you calculate the third order predictor with the given information?

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Problem 6

Consider a DPCM coder with a first order predictor $s_n=0.97^* s_{n-4}$. Assume that the signal has a dynamic range $[-128,127]$. Encode the audio signal belll.wav. Use the quantization step-sizes $\{1,2,3,4,5,6\}$, and plot the rate-distortion performance.

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Problem 7

Explain how the psychoacoustics properties of the human ear can be exploited for audio compression.

Marisa A

Numerade Educator

Problem 8

How is the bit-allocation performed in a perceptual subband coder? How is the masking threshold determined for an audio signal?

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01:02

Problem 9

In audio coding, the audio signal is generally divided into blocks of audio samples., which are then coded individually. What are the advantages of this blocking method? Compare the performance of long and short blocks.