從BT到P2P流媒體

IPTV目前仍是以CHT MOD或Youtube各具代表,但新興軟體實在不能小看。像PPStream，除了亮麗的外觀外，在繁體電腦安裝也能自動轉換語言（從前試過很多也是不行的），表現十分穩定；唯獨自家網站提供的下載位置經常斷線，要到別的網站抓。

其實網路收看一般電視節目並非新鮮事，上屆世界杯我也嘗試這樣做。不過，緩衝很大，也極慢，看不到幾十秒就會停住一輩子，實在不划算。現在除了全球的頻寬擴大了以外，配合點對點流媒體（p2p streaming）的技術，網上接收視訊便不再是苦差了。

到底點對點流媒體是什麼技術呢？隨便在網路上找了一下，找到All-Streaming-Media的答案：

Software like PPLive, PPStream, Coolstreaming, QQLive, SopCast, Feidian, TV Ants allows users to watch streaming media (TV channels) based on BitTorrent (BT) p2p technology.

Because BitTorrent p2p technology is used, every user viewing media with p2p streaming Internet TV software uploads content at the same time the TV programs are downloaded and viewed. Since all viewers upload content when viewing media, everyone becomes a broadcaster (server) without the cost of traditional streaming. And hence, the more users are online, the faster the programs can be loaded. p2p technology also enables a client to automatically find different connection nodes (other users) and download media stream data from the nearest node (the user with the nearest location). The good thing is, stream data is buffered in the memory, not on the hard disk.

那便是來自BT的「分享概念」囉！按照BT的原理，愈多人下載（同時是分享），下載的速度便愈快吧？是的：

Since p2p technology relies on sharing, the more media data segments one uploads to other users, the more segments he himself is entitled to download from others. That is why it may take several minutes before the received stream would run continuously. One has to upload to other users at a rate high enough to be able to download segments in a sufficient rate himself. Therefore it is recommended to establish a connection as early as possible before the starting time of a desired event. The more users sharing segments there are the better stream each one of them will get.

哈哈！所以啊，像世界盃這種人人都在同一時間收看的節目，是絕不擔心斷線的！反而愈多人看愈好！