babynieshal
Oct 14, 2010, 04:49 AM
Consider a two party networked video-conferencing application using MPEG. Say M and N are the two persons holding a conference meeting using the application. Because of delay (due to coding, network transmission, and decoding) in the system, whenever Mdoes something at time t, it will not be seen by N until time t + . The same descriptionapplies for communication from N to M. Suppose study has shown that the delay willbecome annoying to M or N if it gets greater than 150 ms.Assume the following system parameters: (I) it is taking 30 ms to transport a pictureof any type one trip (in either direction) through the network, (ii) the times to decode andencode an I picture are 10 and 20 ms, respectively, (iii) the times to decode and encode a Ppicture are 12 and 25 ms, resp. (iv) the times to decode and encode a B picture are 15 and30 ms, resp, (v) the video frame time is 33 ms (for a frame rate of close to 30 per second),and (vi) the delay to capture and digitize a picture is negligible.If you are to design a GOP for the above application, which is of the form I(B) n P(B) nP(B) n ,where (B) nmeans a B picture repeated n times, what is the maximum value of n you canuse without violating the delay constraint of your application? Assume that encoding (resp.decoding) of a picture can take place as soon as (but not before) all of its reference picture(s)have been encoded (resp. decoded). Clearly show the steps of your calculation