多媒體串流播放緩存之輸出控制技術

Output Control of Multimedia Stream Playback Buffer

蘇奕宇(Yi-Yu Su) ； 高靖鈞(Ching-Chun Kao) ； 劉炳傳(Pin-Chuan Liu)

《電腦與通訊》 149期 (2013/02) Pp. 81-86

摘要

隨著Internet服務的多樣化，以及影音錄製／播放裝置的普及，使用電腦或手持裝置經由網路觀看多媒體影音串流已成為網路的主要應用。使用者播放影音串流時，需將自網路接收之影音串流資料局部下載儲存，再輸出至播放軟體以供觀看或聆聽。當播放端的緩衝空間較小或網路狀態不穩定時（如行動或手持式裝置），容易因緩存溢出或不足而造成影音串流播放中斷或畫面閃爍。一般的作法是將複雜之串流傳輸控制協定實作於播放器端及輸出控制端，如此需付出較高之開發與維護成本同時亦限制播放軟體搭配與選擇之彈性。本文提出媒體影音串流資料輸出之控制技術，基於串流資料封包之時間戳記，利用系統等待指令並檢查系統時間，將串流資料準確的輸出，使播放端可順利播放。本方法不需實作複雜的串流控制協定，並具有準確輸出的特性，特別適用於輕量化播放裝置或軟體，亦利於節省播放端的緩衝記憶體。

關鍵字

多媒體串流 ； 即時串流協定 ； 時間戳記

並列摘要

With the diversification of Internet service s/applications and audio/video recording/playback devices, using PC or handheld devices to play multimedia streams has become the main application of the Internet. Typically, multimedia stream data has to be received and partially stored, and then to be outputted to player or playback software for viewing or listening. Buffer overflow/underflow caused by an unstable network(e.g. bursty traffic) is very likely to result in video playback flickering or stuttering. A general but complicated way to accomplish playback buffer output control is to implement complex streaming protocol. However, it has to pay a higher development and maintenance costs and also reduces the flexibility of choosing compatible playback software. In this paper, based on the timestamp of streaming data, we propose a buffer output control mechanism of multimedia stream playback. The sleep instruction and system time is employed to regulate the streaming data and thus can be outputted correctly and played smoothly. The proposed method does not need to implement complex streaming protocol, which is especially suitable for lightweight playback device/software.

並列關鍵字

Multimedia Streams ； Real Time Streaming Protocol (RTSP) ； Timestamp