一個基於WiFi Direct的多媒體隨選串流機制之研究

Abstract

由於近年來無線通訊技術之蓬勃發展，WiFi已經成為數位家庭中最普遍使用的無線網路環境。現今的數位家庭技術有數位生活網路聯盟（Digital Living Network Alliance；DLNA）、無線顯示技術如Miracast等應用，但隨著行動裝置普及，許多生活上的媒體資訊內容不像傳統那樣地集中於資料中心，而是在家人或朋友之手持裝置間分享，因此需要更加彈性與方便的整合系統。 WiFi聯盟在2010年發表公布WiFi Direct技術，讓裝置間可直接連線而不需無線基礎網路、高頻寬、與高相容性，使得未來搭載WiFi Direct的裝置會越來越普遍。因此本論文提出數位家庭結合WiFi Direct技術，提供日漸多元之家庭使用環境的一套整合系統，達到多裝置的串連整合，方便媒體內容之分享使用。 本系統實現在Android 4.0以上的裝置，稱為DroidCast，它成功的整合各裝置間的媒體資訊內容，並以HTTP串流技術提供即時的隨選視訊，使用WiFi Direct的高傳輸頻寬與直連優勢，讓數位家庭的使用者之間更加容易分享多媒體內容。 我們在WiFi Direct上發展了一套即時隨選串流機制，並實際透過實驗測試性能，結果顯示在充裕的頻寬下無論是低流量或是高流量媒體內容都可順暢地播放。本系統提供一個新的應用方向，期望未來在數位家庭有更多的應用推廣。

In recent years, wireless communication technologies advanced quickly, and WiFi has become the most popular residential wireless technology. Nowadays digital home technologies such as Digital Living Network Alliance （DLNA） and wireless display technology applications such as Miracast are widely deployed. However, the population of mobile device user growed rapidly, and media contents were distributed among these users, which may need to share contents with each other thru mobile devices. WiFi Alliance announced WiFi Direct technology in 2010. The advantage of WiFi Direct is that the devices can be connected directly without infrastructured wireless network, high bandwidth, and high compatibility. Thus, the devices equipped with WiFi Direct would become more and more common in the future. This thesis presents a media streaming mechanism for digital home based on WiFi Direct technology, providing an integrated system that is easy to share and easy to use among devices for complex environment at home. The system is called DroidCast, it works in Android 4.0 and above. Our DroidCast integrates media content among devices successfully, it allows HTTP streaming to provide real-time and on-demand playback between mobile devices in proxmity. Through WiFi Direct, high bandwidth and directly connection could be achieved easily in digital home. The performance evaluation shows that the system could play media contents smoothly with either low bit rate or high bit rate. The system provides a new approach for the development of media streaming applications.