Christos Tryfonas. MPEG-2 Transport over ATM Networks. Master's thesis, University of California at Santa Cruz, September 1996.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....throughput and low delay. We will present simulation results for terrestrial and satellite configurations. 8.17.1 Overview of MPEG 2 over ATM In this section, we give a short introduction to the MPEG 2 over ATM model and introduce some MPEG 2 terminology. For a detailed discussion, see reference [111]. 312 Figure 8.13: Overview of MPEG 2 Transport Streams The MPEG 2 standard specifies two kinds of streams to carry coded video: the Transport Stream and the Program Stream . The latter is used for compatibility with MPEG 1 (used for stored compressed video audio) while the former is used ....

....Transport Streams 315 The key point is that the MPEG 2 rate is piecewise CBR. As shown in Figure 8.15, the program s rate (not the transport stream s rate) is constant between successive MPCRs. The maximum rate is bounded by a peak value (typically 15 Mbps for HDTV quality compressed video [111]) The choice of the rates between MPCRs is implementation specific, but in general depends upon the buffer occupancy, and the rate of generation of the elementary streams. The transport stream packets are encapsulated in AAL5 PDU with two transport stream packets in a single AAL5 PDU (for ....

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Christos Tryfonas. MPEG-2 Transport over ATM Networks. Master's thesis, University of California at Santa Cruz, September 1996.

....timestamps (called Program Clock References or PCRs in MPEG 2 terminology) within the packets facilitates the clock recovery at the decoder end ensures synchronization and continuity of MPEG2 Transport Streams. For a brief tutorial of the MPEG 2 Systems Layer the interested reader is referred to [16, 20]. When transporting MPEG 2 encoded streams over packet switched networks several issues must be taken into account. Some of these include the choice of the adaptation layer, method of encapsulation of MPEG 2 packets into network packets, provision of Quality of Service in the network to ensure ....

....of the first order Butterworth LPF used in the analysis. where P(s) is given by P(s) K (1 KL(s) s L(s) 2.13) In order to model the LPF, we used a first order Butterworth analog LPF with a cutoff frequency of 0.1 Hz. This cutoff frequency was derived from both the experimental results of [20] and the analysis done in [10] Following the methodology presented in [15] we get L(s) 2.14) S Sl with s being the single real pole of the filter that has a value of Sl = 2rO.1 exp(jr) 0.2r exp(jr) 0.2r. 2.15) Hence, from Eq. 2.14) and (2.15) we obtain L(s) 2.16) s ....

C. Tryfonas. MPEG-2 transport over ATM networks. Master's thesis, University of California at Santa Cruz, September 1996. Available at http://www. cse. ucsc. edu/research/hsnlab.

....increasingly being used for the transport of real time voice and video streams. MPEG 2 is the dominant standard for transport of compressed video streams in packet networks [7, 8] The MPEG 2 Systems Layer defines two ways to multiplex elementary audio, video or private streams to form a program [15, 17] the Program Stream and the Transport Stream. The MPEG 2 Transport Stream format is the preferred choice in environments where losses are likely to occur, as in the case of transport over a packet switched network. It is currently used in Digital Video Broadcasting (DVB) systems for digital ....

....sake of convenience, we need to assume a specific LPF for the PLL design. In this analysis, we use a first order Butterworth analog LPF with a cutoff frequency of 0.1 Hz. This cutoff frequency provides good stability and tracking performance to the decoder PLL as shown experimentally by Try fonas [17] and analytically by Kaiser [9] The transfer function of a first order Butterworth LPF is given by 0.27r L(8) 8 81 with s being the single real pole of the filter that has a value of 81 = 2rO.1 exp(jr) 0.2r exp(jr) 0.2r. 6) Hence, from Eq. 5) and (6) we obtain 0.27r ....

C. Tryfonas. MPEG-2 transport over ATM networks. Master's thesis, University of California at Santa Cruz, September 1996. Available at http://www. cse. ucsc. edu/research/hsnlab.

....constant average delay through the buffer [67] Almost all the techniques described above relate the clock recovery problem with the buffer dynamics at the receiver. Our approach is primarily motivated by our observa tions from extensive simulations of MPEG 2 Transport Streams over ATM networks [74]: Although we found that the quality of the reconstructed clock was degraded even with moderate amounts of jitter, the jitter did not cause the MPEG 2 system decoder buffer to overflow or underflow. This suggests the possibility of combining the two buffers the dejittering buffer and the system ....

....packet carrying the first PCR experiences maximum jitter and all the other incoming packets with PCR values have negligible jitter, then the locking time may be high depending on 92 due to low gain. Besides, although the method proposed m mimizes the effects of high jitter autocorrelation [4, 74], it does not eliminate the problem since it only compresses the error term. In general, restamping algorithms based on heuristics similar to the one described earlier in this section estimate the frequency based on packets that have delays falling into a small zone called the clocking delay zone ....

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C. Tryfonas, MPEG-2 Transport over ATM Networks, Master's thesis, University of California at Santa Cruz, September 1996, Available at http: //www. cse. ucsc. edu/research/hsnlab.

....(called Program Clock References or PCRs in MPEG 2 terminology) carried within the packets, MPEG 2 Transport Streams ensure synchronization and continuity, and provide ways to facilitate the clock recovery at the decoder end. Detailed descriptions of the MPEG 2 Systems Layer can be found in [15, 19]. Several issues need to be considered when transporting MPEG 2 encoded streams over packetswitched networks. These include the choice of the adaptation layer, method of encapsulation of MPEG 2 packets, choice of scheduling algorithms in the network for control of delay and jitter, and the design ....

....variation to avoid overflowing or underflowing the dejittering buffer. Several products are designed based on a maximum value of 10 ms for the jitter. Our simulations of MPEG 2 traffic over an ATM network showed that the jitter often exceeds 10 ms, severely degrading the recovered clock signal [19]. In addition, this approach wastes memory by using two separate buffers, the system decoder buffer and the dejittering buffer. Another approach to tolerate jitter at the receiver is to use special pre filtering techniques to filter the delay variation before the PLL [7] A third technique to ....

[Article contains additional citation context not shown here]

C. Tryfonas. MPEG-2 transport over ATM networks. Master's thesis, University of California at Santa Cruz, September 1996. Available at http://www.cse.ucsc.edu/research/hsnlab.

....timestamps (called Program Clock References or PCRs in MPEG 2 terminology) within the packets facilitates the clock recovery at the decoder end ensures synchronization and continuity of MPEG2 Transport Streams. For a brief tutorial of the MPEG 2 Systems Layer the interested reader is referred to [16, 20]. When transporting MPEG 2 encoded streams over packet switched networks several issues must be taken into account. Some of these include the choice of the adaptation layer, method of encapsulation of MPEG 2 packets into network packets, provision of Quality of Service in the network to ensure ....

....Butterworth LPF used in the analysis. where P (s) is given by P (s) K 1 Gamma KL(s) s KL(s) L(s) 2.13) In order to model the LPF, we used a first order Butterworth analog LPF with a cutoff frequency of 0.1 Hz. This cutoff frequency was derived from both the experimental results of [20] and the analysis done in [10] Following the methodology presented in [15] we get L(s) 0:2 s Gamma s 1 ; 2.14) with s 1 being the single real pole of the filter that has a value of s 1 = 2 0:1 exp(j ) 0:2 exp(j ) Gamma0:2 : 2.15) Hence, from Eq. 2.14) and (2.15) we obtain L(s) ....

C. Tryfonas. MPEG-2 transport over ATM networks. Master's thesis, University of California at Santa Cruz, September 1996. Available at http://www.cse.ucsc.edu/research/hsnlab.

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Christos Tryfonas. MPEG-2 Transport over ATM Networks. Master's thesis, University of California at Santa Cruz, September 1996.

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C. Tryfonas. MPEG-2 transport over ATM networks. Master 's thesis, UC Santa Cruz, Sept 1996. 9

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Christos Tryfonas. MPEG-2 Transport over ATM Networks. Master's thesis, University of California at Santa Cruz, September 1996.

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Christos Tryfonas. MPEG-2 Transport over ATM Networks. Master's thesis, University of California at Santa Cruz, September 1996.

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C. Tryfonas and A. Varma, MPEG-2 transport over ATM networks, [EEE Communications Surveys 2(4) (1999), 24--33.

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Christos Tryfonas. MPEG-2 Transport over ATM Networks. Master's thesis, University of California at Santa Cruz, September 1996.

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