HALP please

[esjay]

can someone please give me an quick explanation on how we get to the answer! So i can go sleep.

6.6 Assume that we have CD-quality stereo music (Refer Lecture 9). What is the:

i) minimum storage capacity of a CD-ROM to store a 60-minute multimedia title if:
(a) the music is not compressed
(b) the music is compressed for 2 channel stereo (128 kbps)

ii) Minimum time to transmit a 30-second portion of the title using a transmission channel of bit rate 1.5 Mbps if:
(a) the music is not compressed
(b) the music is compressed for 2 channel stereo (128 kbps)


ANSWER:

i) CD quality audio needs 1.411 Mbps bandwidth. So, the storage capacity for 60 minutes is:

(a) without compression

1.411 x 60 x 60 Mbits = 5079.6 Mbits = 634.96 Mbytes

(b) with compression requiring 128 kbps bandwidth


128 x 60 x 60 kbits = 460.8 Mbits = 57.6 Mbytes

ii) Time required to transmit one 30 seconds portion of the title is:

(a) without compression

1.411 x 30/1.5 seconds = 28.22 seconds


(b) with compression requiring 128 kbps bandwidth

128/1000 x 30/1.5 = 2.56 seconds