本論文提出一種漸進式下載之可適性串流方法， 運用現有TCP機制， 設計動態頻寬評估與Virtual Receiver Buffer Emulation (VRBE)機制， 在伺服器端提供多重品質多媒體影音內容自動切換，以適應各種網路狀態，讓使用者獲得最佳串流播放品質。在多媒體影音內容收看的過程中，本機制利用TCP RTT (Round Trip Time)進行可用頻寬評估， 以VRBE機制， 擬真接收端播放緩衝區狀態，最後依據可用頻寬與接收端緩衝區消長狀態等資訊，由伺服器端動態改變傳送不同品質之多媒體影音內容， 讓用戶端播放器可以適應各種網路狀態變化， 以達到最佳串流播放播放品質。

In this paper, we proposed an adaptive streaming delivery mechanism with progressive download, which utilize the Virtual Receiver Buffer Emulation (VRBE) mechanism. In our scheme, the streaming server provides contents with different qualities and switches between them to adapt to the network states. Moreover, the client users can receive the sufficient quality of stream. While delivering the video stream packets, TCP RTT (Round Trip Time) is used to estimate the available bandwidth, and VRBE mechanism is to emulat e the status of receiving buffer in the server side. Based on the available bandwidth and the status of receiving buffer (ascending or descending) the server will switch between different qualities and deliver the contents to clients dynamically. This mechanism can adaptive to the variation of available bandwidth and achieve the best quality of streaming service for users.