Multimedia Applications CIS 413
Fall 2011
Home Assignment 2
Due Date:
[1%] 1. Assume that a digital video has the following format:
picture resolution: 640 x 480 pixels; frame rate: 30 frame/second
YCbCr color model: 8-bit each for Y, Cb and Cr; chroma subsampling: 4:2:2
Please write down the raw data amount (in bytes), i.e., without compression, for 1-minute video
of this format.
[4%] 2. Playout Buffer for Audio: Audio has stringent timing requirements and needs virtually
constant playback speed for acceptable quality. Assume that you try to play an online audio file
stored at a remote server, which sends out the audio stream data at a constant rate, r bits per
second. Since the delay over the Internet from the remote server and your client computer may
be variable, the stream data arriving at your client computer may not have a constant rate. An
approach to re-creating a constant bit stream is to smooth the delay variation in a playout buffer
at the client side. It operates as follows. When the first bit of the data stream arrives, it is stored
in the buffer until a fixed time, T seconds, has elapsed. Then the buffer is served at a constant
rate r (bits per second) whenever it is not empty. Assume that the network delay variation is
bounded by T seconds.
[1.5%] (a) Prove that the playout buffer never starves and produces a constant output at rate r
bits per second.
[1.5%] (b) What is the minimum requirement on the playout buffer size to avoid buffer
overflow?
[1%] (c) Assume that the network delay variation is bounded by 0.1 seconds. Based on your
result in (b), calculate the minimum requirement on the size of playout buffer for streaming an
online audio file with the following audio quality: 2 bytes per sample, 44.1 kHz, 2 stereo
channels.
docsity.com
