Document Type

Other

Publication Date

4-2003

Abstract

New TCP-Friendly requirements expect multimedia flows to reduce their data rates under packet loss to that of a conformant TCP flow. To reduce data rates while preserving real-time playout, temporal scaling can be used to discard the encoded multimedia frames that have the least impact on perceived video quality. To limit the impact of lost packets, Forward Error Correction (FEC) can be used to add repair frames damaged by packet loss. However, adding FEC requires further reduction of the multimedia data, making the decision of how much FEC to use of critical importance. Current approaches use either inflexible FEC patterns or adapt to packet loss on the network without regard to TCP-Friendly data rate constraints. In this paper, we derive analytically model the playable frame rate of a TCP-Friendly MPEG stream with FEC and temporal sealing. Our model captures the impact of specific FEC amounts for different MPEG frame types and accounts for interframe dependencies. For a given network condition and MPEG video encoding, we use our model to exhaustively search for the optimal combination of FEC and temporal sealing that yields the highest playable frame rate within TOPFriendly constraints. Analytic experiments over a range of network and application conditions indicate that adjustable FEC with temporal sealing can provide a significant performance improvement over current approaches. Extensive simulation experiments based on Internet traces show that our model can be practically effective as part of a streaming protocol that chooses FEC and temporal sealing patterns that meet the current application and network conditions.

DOI

WPI-CS-TR-03-10

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