| The technology of realtime audio-video transmission has been widely used in our daily lives. Audio-video data is transmitted from Peer-to-Peer (P2P) through Network Address Translation (NAT) devices based on User Datagram Protocol (UDP). Due to the unreliability of UDP, H.264 video stream without Flexible Macroblock Ordering (FMO) may lose some data packages while transmission, which will cause decoding failure. This thesis is aimed at providing a method for reliable P2P transmission to make audio-video data reach the destination and can be appropriately decoded.This design contains the master used to send audio and video, the client used to receive audio and video, and the server used to guide the P2P connection. This design uses a technology to establish P2P connection and modified packets maintenance method referring to Transmission Control Protocol (TCP) to realize reliable transmission. Moreover, this design uses the low cost algorithm and analyses different types and positions of video data to decide different priority. So when packet loss happens, low priority packet will be discarded first to improve the system’s resistance to packet loss. The real-time audio-video of P2P transmission system described in this thesis can transmit VGA 400kbps～720P 1600kbps H.264 encoded video and 44.1 kHz dual channel ADPCM audio in the network bandwidth no less than 500kbps. Compared to TUTK platform, the average effective frames per second is 30% higher in 500kbps bandwidth.Therefore, in this thesis, the design of real-time audio-video P2P reliabe transmission system is suitable for various conditions using the h.264 video format and ADPCM audio format, such as IP Camera, video phone, remote visual car etc. |
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