Chapter 7

There are two types of redundancy in video. Describe them, and discuss how they can be exploited for efficient compression.

Suppose an analog audio signal is sampled 16,000 times per second, and each sample is quantized into one of 1024 levels. What would be the resulting bit rate of the PCM digital audio signal?

Multimedia applications can be classified into three categories. Name and describe each category.

Consider a DASH system for which there are $N$ video versions (at $N$ different rates and qualities) and $N$ audio versions (at $N$ different rates and versions). Suppose we want to allow the player to choose at any time any of the $N$ video versions and any of the $N$ audio versions. a. If we create files so that the audio is mixed in with the video, so server sends only one media stream at given time, how many files will the server need to store (each a different URL)? b. If the server instead sends the audio and video streams separately and has the client synchronize the streams, how many files will the server need to store?

List three disadvantages of UDP streaming.

Consider the simple model for HTTP streaming. Suppose the server sends bits at a constant rate of 2 Mbps and playback begins when 8 million bits have been received. What is the initial buffering delay $t_p$ ?

CDNs typically adopt one of two different server placement philosophies. Name and briefly describe these two philosophies.

What is the difference between end-to-end delay and packet jitter? What are the causes of packet jitter?

Why is a packet that is received after its scheduled playout time considered lost?

a. Consider an audio conference call in Skype with $N>2$ participants. Suppose each participant generates a constant stream of rate $r$ bps. How many bits per second will the call initiator need to send? How many bits per second will each of the other $N-1$ participants need to send? What is the total send rate, aggregated over all participants? b. Repeat part (a) for a Skype video conference call using a central server. c. Repeat part (b), but now for when each peer sends a copy of its video stream to each of the $N-1$ other peers.