Streaming Video Compression
The key to video streaming is data compression. Uncompressed video files can be HUGE - several megabytes for a short clip. It would be impossible to transmit that amount of data over the Internet to view the video in real time.
Compression reduces the size of the video file so that there is less data to transmit. Without compression there would be no streaming video.
Of course there's a trade-off. Video compression works by discarding parts of the video file, and this means that the compressed video will be of lesser quality than the original. Quite simply, the more compression the poorer the video.
Generally speaking, there is no such thing as "One size fits all" in terms of video compression (see below). Faster Internet connection speeds allow more data to be transmitted, so if most of your viewers have DSL connections you can have a better quality streaming video than if your viewers have dial-up connections.
Since there's no way of knowing what speed your viewers are going to connect at, you have to make some choices when it comes to encoding your file for video streaming. Either you make one highly compressed video file that caters to the lowest connection speeds or you make several versions with different levels of video compression.
One File Fits All
It is possible to make one file fit all by encoding the video file with Multiple Bit Rates (MBR). The drawback to this type of video file is that it cannot be hosted on a regular HTML server - you must use a streaming server.
Hosting a streaming video on a streaming server has some advantages and disadvantages. One of the big advantages to MBR is that the server detects the incoming connection speed and automatically delivers an appropriate video stream. This means that the viewer does not have to choose from a variety of streaming video files - there is just one "Play" button for all connections. This makes for a streamlined interface which is less confusing and easier to use.
Another advantage of streaming servers is that they can handle more requests and higher bandwidth than HTML servers, so if your streaming video is a huge success and gets millions of hits every day, you're going to have to host it on a streaming server.
The downside of MBR for streaming video files is that the dimensions of the video are constant no matter how fast the connection. If you have different versions of your video file for different connection speeds, you can have larger dimensions for the fast connections and smaller dimensions for slow connections.
A good option to accommodate a variety of connection speeds for streaming video is to make different versions with different compression rates and video dimensions. The main drawback here is that the viewer must choose which version to watch, so to avoid confusion keep the number of choices down to three.
Besides the dimensions of the video image and level of compression, another factor that affects the size of the streaming video file is frame rate, expressed as frames per second (fps). A higher frame rate will make the video smoother, but will also make the video file larger. Movies have a frame rate of 24 fps, so streaming video should usually be less than that - somewhere between 10 and 20 fps.
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