Question 1

Speech coders using block-wise coding usually introduce delays. If the length of the speech analysis frame is 25 msec, give a reasonable estimate of the delay on the receiver side.

Accepted Answer

The encoder has to wait until a whole frame has been collected before processing; this introduces a $25 \mathrm{~ms}$ delay. 
Pitch analysis usually needs at least one frame buffering for smoothing. Adding the times for encoding and decoding, the delay is usually $3 *$ frame\_size $=75 \mathrm{~ms}$.

Question 2

Work out the following problem of MPEG motion vector search in detail. 
The Target (Current) Frame is a B-frame. The size of macroblocks is $4 \times 4$ and the search range is the entire picture.
The macroblock in question (darkened) in the frame has its upper-left corner at $\left(x_{t}, y_{t}\right)$. It contains 12 dark pixels, each with intensity value 10. the other 4 pixels are part of the background, which has a uniform intensity value of 100 . There are obstacles in the scene having light pixels with value 50 .
The complete scene is described in the figure.
What is the best motion vector for coding this frame?

Accepted Answer

Not Answer

Question 3

In MPEG's polyphase filter bank, if $24 \mathrm{kHz}$ is divided into 32 equal-width frequency subbands, 
(a) What is the size of each subband?
(b) How many critical bands, at worst, does a subband overlap?

Accepted Answer

(a) 750 Hz/band.
(b) 6 or 7.

Question 4

Multiplexing enables users to share the capacity over a physical link. How does FDM (Frequency Division Multiplexing) work?

Accepted Answer

The answer of Multiplexing enables users to share the capacity...

Question 5

Switching is important for interconnection of telephone networks. What are the two main switching technologies? How do they work?

Accepted Answer

The answer of Switching is important for interconnection of telephone...

Question 6

Both UDP and TCP are used in the Transport layer in TCP/IP networks. Discuss the differences between UDP and TCP.

Accepted Answer

The answer of Both UDP and TCP are used in...

Question 7

What is the compression ratio of MPEG audio if stereo audio sampled with 16 bits per sample at $48 \mathrm{kHz}$ is reduced to a bitstream of $256 \mathrm{kbps}$ ?

Accepted Answer

The answer of What is the compression ratio of MPEG...

Exam 6: Mpeg Video Coding I -- Mpeg-1 and 2, Basic Audio Compression Techniques, Mpeg Audio Compression, Computer and Multimedia Networks

Speech coders using block-wise coding usually introduce delays. If the length of the speech analysis frame is 25 msec, give a reasonable estimate of the delay on the receiver side.

In MPEG's polyphase filter bank, if 24kHz24 \mathrm{kHz}24kHz is divided into 32 equal-width frequency subbands, (a) What is the size of each subband? (b) How many critical bands, at worst, does a subband overlap?

Multiplexing enables users to share the capacity over a physical link. How does FDM (Frequency Division Multiplexing) work?

Switching is important for interconnection of telephone networks. What are the two main switching technologies? How do they work?

Both UDP and TCP are used in the Transport layer in TCP/IP networks. Discuss the differences between UDP and TCP.

What is the compression ratio of MPEG audio if stereo audio sampled with 16 bits per sample at 48kHz48 \mathrm{kHz}48kHz is reduced to a bitstream of 256kbps256 \mathrm{kbps}256kbps ?

In MPEG's polyphase filter bank, if $24 \mathrm{kHz}$ is divided into 32 equal-width frequency subbands, (a) What is the size of each subband? (b) How many critical bands, at worst, does a subband overlap?

What is the compression ratio of MPEG audio if stereo audio sampled with 16 bits per sample at $48 \mathrm{kHz}$ is reduced to a bitstream of $256 \mathrm{kbps}$ ?