See Movies Online 4

Streaming technology has made listening to music or watching movies on the web as easy as turning on the radio or TV. Here's how the technology works.

The very first music and movie files you might find on the internet were just short clips because you had to download the entire file before you decide to could play it. In recent times, on the other hand, you can start playing the file as soon as the first bytes begin to arrive... due to streaming.

This immediacy is possible because streaming won't send files over the internet the same way since several other files are sent. It uses a different protocol.

A protocol is a group of rules defining how two computers connect with each other and how they send each other data.

Most data which is sent over the internet is first broken up into packets (small blocks of data). The packets are sent separately and also are the rejoined at their destination in order that the receiver gets the whole file.

The sending of most data on the internet is governed by a set of rules called the Transmission Control Protocol (TCP). Streaming however uses the User Database Protocol (UDP).

These two protocols are quite different. The crucial difference is in how they check for errors.

If one packet gets damaged when downloading will be controlled by TCP, downloading will be suspended while that packet is resent. That way, once the download has been completed, you can be sure that you have the entire data file.

When you are streaming files, however, UDP allows packets to get lost now and then without interrupting the downloading. This is fine because, when an occasional packet is lost, you are unlikely to notice any interruption to the music or movie. But if everything froze very briefly while a lost packet was being resent, you probably would notice the interruption.

With streaming technology, you do not have to wait for files to be downloaded entirely before you can begin listening to audio or watching a video. You can listen to a concert on another side of the world in real time, make a video call or watch a film much like on tv.

Streaming video works in a similar way to streaming audio, except that the video must be split into its separate audio and video components when it really is in the buffer within the RAM.

The server that holds the video for streaming may have a video capture expansion card which may capture either a live feed from a video camera or perhaps a pre-recorded video. The capture board turns the analogue signals it receives into digital data and compresses it.

At the same time, it employs a trick to prevent having to capture more data than it needs as a way to make transmission easier.

When the camera used to record the video is stationary, ie, it really is not panning, the total amount of data created can be reduced. This may be done because all moving images are made up of a series of frames (still images) that change in rapid succession to provide the illusion of continuous movement. The rate is generally 30 frames a second which gives the video a smooth look.

The compression system lessens the range of frames needed by comparing adjacent frames and Suggested Reading only taking account of pixels that change from one frame to another. It does this by establishing what the background looks like.

As long as the camera remains however, only the changes in the frame, for example the movement of the actors, have to be transmitted. The background only has to be transmitted again in the event the camera starts to pan and also the background changes.

Video streaming will likely skip frames when your Internet link is slow, which may make the video jerky. Thus the faster your connection, the smoother the video will be.

When your computer receives the video signals, it shall decompress them and load them in to a small buffer in RAM as it does for audio.

At this point the signals are split into separate video and audio components that are sent to the video card and sound card respectively, whence they may be output to your monitor and speakers so you can watch the film and hear the sound-track.