Module 11: Practice Quiz

Question 1

When streaming stored audio and video, the content starts playing within a few seconds of receiving data, instead of waiting for the entire file to download first.

T/F

Answer 1

TRUE

This characteristic defines streaming as a method of delivering media.

Question 2

Streaming audio and video is interactive and should have a continuous playout.

T/F

Answer 2

TRUE

Continuous playout is essential for a smooth streaming experience.

Question 3

Streaming live audio and video is usually not interactive and is delay-sensitive.

T/F

Answer 3

TRUE

Live streaming often requires real-time delivery, making it sensitive to delays.

Question 4

Conversational voice and video over IP is a service that uses traditional circuit-switched telephony networks.

T/F

Answer 4

FALSE

VoIP uses packet-switched networks instead of traditional circuit-switched networks.

Question 5

The rounding of samplesto a discrete number in a particular range is called quantization.

T/F

Answer 5

True

Quantization is a key process in digital signal processing.

Question 6

The only consideration when encoding VoIP is to use as little bandwidth as possible.

T/F

Answer 6

FALSE

Other factors, such as quality and latency, are also important.

Question 7

When using VoIP, all packets are transmitted, regardless of any end-to-end delay, to make sure that no message is unaccounted for.

T/F

Answer 7

FALSE

VoIP often prioritizes timely delivery over retransmission of lost packets.

Question 8

Which service maintains a jitter buffer as a mechanism for mitigating jitter?

Answer 8

VoIP

Jitter buffers help smooth out variations in packet arrival times.

Question 9

Most of the time, VoIP uses —— to transmit audio.

Answer 9

UDP

UDP is preferred for its low latency in real-time communications.

Question 10

Which of the following applications has less delay tolerance (i.e. a lower threshold in terms of when a packet is considered lost)?
- VoIP
- File transfer
- Stored audio and video streaming

Answer 10

VoIP

VoIP requires timely delivery for effective communication.

Question 11

Which of the following services is the least sensitive to network delays?
- VoIP
- File transfer
- Stored audio and video streaming

Answer 11

File transfer

File transfers can tolerate delays better than real-time services.

Question 12

Assuming that retransmissions are not allowed, which of the following services would be the most tolerant to packet losses?
- VoIP
- File transfer
- Stored audio and video streaming

Answer 12

VoIP

VoIP can handle some packet loss without significant degradation in quality.

Question 13

Which of the following decreases the end-to-end delay when using VoIP?
- UDP
- TCP

Answer 13

UDP

UDP reduces latency compared to TCP.

Question 14

Which of the following is more likely to result in packet losses when using VoIP?
- UDP
- TCP

Answer 14

UDP

While UDP is faster, it does not guarantee delivery, leading to potential losses.

Question 15

When using Forward Error Correction, the redundant data that is transmitted alongside the main transmission could be a copy of the original data divided into chunks or could also be a lower-quality version.

T/F

Answer 15

TRUE

This technique helps recover lost data without needing retransmission.

Question 16

An advantage of using Interleaving is that there is no added latency.

T/F

Answer 16

FALSE

Interleaving can introduce some latency due to the rearrangement of data.

Question 17

Error concealment can be computationally cheap if a lost packet is simply replaced with a previous packet.

T/F

Answer 17

TRUE

This method is a simple way to handle lost packets in VoIP.

Question 18

Video delivery is tolerant to packet losses. Reliability of packet delivery is not that important.

T/F

Answer 18

FALSE

While video can tolerate some loss, reliability is still important for quality.

Question 19

Content providers store all the intelligence to download the video at the server.

T/F

Answer 19

False

The server manages the delivery of video content to clients.

Question 20

What is the first item downloaded by a client’s video player?

Answer 20

A manifest file

The manifest file contains metadata about the video content.

Question 21

Suppose Alice is using a cloud service to listen to many MP3 songs, one after the other, each encoded at a rate of 128 kilobits per second (kbps). Suppose that she downloads for 30 minutes (1800 seconds). How many megabytes (MB) of data are transferred during the 30-minute session?

Answer 21

29

This calculation is based on the bitrate and duration of the session.

Question 22

Suppose Bob is using a cloud service to watch video encoded at a rate of 2 megabits per second (Mbps). Suppose that his session lasts for 30 minutes (1800 seconds). How many megabytes (MB) of data are transferred during the 30-minute session?

Answer 22

450

The data transfer is calculated based on the bitrate and session duration.

Question 23

One of the goals of quality of experience is to have high re-buffering.

T/F

Answer 23

FALSE

High re-buffering negatively impacts user experience.

Question 24

Assume the available network bandwidth is 15 Mbps and the bitrate of the chunk is 3 Mbps. Determine the buffer-filling rate and the buffer-depletion rate.

Answer 24

5,1

This reflects the difference between bandwidth and bitrate.

Question 25

Consider a case where a video player experiences a bandwidth drop in a case of bandwidth overestimation with rate-based adaptation. Assume that: - For the first 25 seconds, the bandwidth is 5 Mbps - Available bitrates are {250kbps, 500 kbps, 1 Mbps, 2 Mbps, 3 Mbps} - Chunk size is 3 Mbps At time t = 25 seconds, the bandwidth drops to 300 kbps. The buffer occupancy at the time of the bandwidth drop was 15s. Calculate how long it takes to download a 5-second chunk.

Answer 25

(3 Bbps / 300kbps) x 5s = 50s ## Footnote This calculation shows the impact of bandwidth on download time.