Research And Implementation Of Audio And Video Communication And Recording/Playback System Based On PJSIP

With the development of digital signal processing technology and Internet communication technology, we can gradually find relevant Internet products to take the place of some traditional telecommunications services, the mobile communication services are also gradually applied IP networks to achieve audio and video communication. Although the audio and video communication system based on IP networks could not reached the level that based on traditional circuit-switched networks in quality and safety, it has become a popular product R&D direction due to greater advantages on operation, interaction and price with the growing popularity of audio and video communications terminal equipment.For researching and developing product prototype of audio and video communication system, this paper does further research based on PJSIP, an open source multimedia communication library, and focus on audio and video, including audio and video codec, recording and playback function, quality of service assurance technology. Because the audio and video framework in PJSIP, called PJMedia, is still in the development stage, it only provides conservative codec and limited relevant media functions. One of the objectives of this paper are adding new audio codec, called Opus, and video codec, called VPx, which are modern and suitable for media network communication, and implementing basic audio and video recording and playback functions. The objectives aim at improving the quality and stability of media communication as well as the PJMedia framework. Another objective of this paper is to purpose a Qo S assurance strategy with the help of the communication module and media module, and implement it in the PJMedia framework. Doing research on Region of Interest(ROI) Extraction, Background Subtraction(BS), Quantization Parameter(QP) Adjustment by Region and etc. Making use of VPx Codec’s feature and evaluate the network status from communication module to achieve such Qo S assurance strategy with the method of extracting ROI for QP adaptive adjustment under network status.All the effort done on PJMedia framework is to improve the audio and video communication system achieved in this paper. Experiment and analysis demonstrate that thesystem has good media communication quality and Qo S assurance strategy works well.