Question
Recall the simple model for HTTP streaming shown in Figure 7.3. Suppose the buffer size is infinite but the server sends bits at variable rate x(t). Specifi- cally, suppose x(t) has the following saw-tooth shape. The rate is initially zero at time t = 0 and linearly climbs to H at time t = T. It then repeats this pattern again and again, as shown in the figure below.
a. What is the server’s average send rate?
b. Suppose that Q = 0, so that the client starts playback as soon as it receives a video frame. What will happen?
c. Now suppose Q > 0. Determine as a function of Q, H, and T the time at
which playback first begins.
d. Suppose H > 2r and Q = HT/2. Prove there will be no freezing after the initial playout delay.
e. Suppose H > 2r. Find the smallest value of Q such that there will be no freezing after the initial playback delay.
f. Now suppose that the buffer size B is finite. Suppose H > 2r. As a function of Q, B, T, and H, determine the time t = t f when the client application buffer first becomes full.
Answer
a)
T he server’s average send rate is 'H/2' as consider the Figure 7.2 and the rate is initially zero at time t = 0 and climbs to H at time t = T.
b)
Assume that Q = 0, so that the client starts playback as soon as it receives a video frame. Then, the play will be hold after printing the first frame.
c)
Assume that Q>0, the function of Q, H, and T the time at the playback first begins, then the following function as:
d)
Assume H > 2r and Q = HT/2
Hence, provied there will be no freezing after the initial playout delay.
e)
Assume H > 2r and there will be no freezing after the initial playback delay,
then the smallest value of Q as:
f)
Assume that the buffer size B is finite. Suppose H > 2r. As a function of Q, B, T, and H, determine the time t = t f when the client application buffer first becomes full.
Then,
