Streaming is a technique for transferring data such that it can be processed as a steady and continuous stream. Streaming technologies are widely used in transmit large multimedia (voice, video and data) files quickly. With streaming, the client browser or plug-in can start displaying the multimedia data before the entire file has been transmitted.
Video streaming technology is developed based on 2 key technologies, the video coding technology and scalable video distribution technology.
Bandwidth efficiency, scalability and flexibility between a video server and client machine is a key issue in the video stream the Internet is the best effort network. The scalable video distributing technology can automatically adjust the amount of data according to the change in bandwidth. Video streaming system consists of an encoder, distribution server and a client that receives the video data. The distribution server stores the encoded video data and begins to distribute it on the client's demand. People can watch the video whenever and wherever by accessing the server on the Internet. Encoding and distribution is carried out in real time in the case of live distribution. Load balance is considered by placing the relay server in the appropriate location on the network.
The most important video codec standards for streaming video are H.261, H.263, MJPEG, MPEG1, MPEG2 and H.264/MPEG4. Compared to video codecs for CD-ROM or TV broadcast, codecs designed for the Internet require greater scalability, lower computational complexity, greater resiliency to network losses, and lower encode/decode latency for video conferencing. In addition, the codecs must be tightly linked to network delivery software to achieve the highest possible frame rates and picture quality.
The transport protocols used in the video streaming are TCP, UDP, RTP and RTSP. For reliable document (such as HTTP files) transfer, TCP is required. UDP provides un-reliable transport of information which can be used to stream video. However, th most porpular transport is the Real Time Transport Protocol (RTP), which is specially designed for the transport of real-time data, including audio and video. The real Time Streaming Protocol (RTSP) is another open standard for delivery of real-time media over the Internet. It defines the connection between streaming media client and server software, and provides a standard way for clients and servers from multiple vendors to stream multimedia content.
Video Streaming Technologies
Related Terms: H.261, H.263, MJPEG, MPEG1, MPEG2, H.264, MPEG4, TCP, UDP, RTP and RTSP