Streaming Video Over The Web
Until recently, digital video files needed to be downloaded in their entirety, after considerable delay, before playback. With web streaming, videos can be played almost immediately as it is transferred from the server to your computer.
Streaming video is just in its infant stages, yet it has a potential limited only by the network bandwidth it requires to send high quality video. However, the bandwidth is expanding exponentially. For the web surfer, this could eventually mean 200 million channels of TV. For video makers, this could be an unprecedented broadcasting opportunity.
What is streaming video?
Streaming video is a term applied to compression and buffering techniques that allow you to transmit and view video in real-time via the Internet.
Instead of having to wait until it is downloaded completely, streaming video starts playing back shortly after beginning its download, as it is still being downloaded from server.
What are the benefits of streaming media?
Before the advent of streaming media technology, multimedia video
and audio clips were downloaded as files (usually .AVI or .MPG) to your
hard disk before you could view them. Then the file had to be opened
using separate software applications like Apple's Quicktime or Microsoft's
Windows Media Player.
Any disadvantages to using streaming media?
Yes, in most cases, video picture quality is compromised, since a viewer's Internet connection speed determines what picture quality they will see. Using downloadable formats such as MPEG-1 or MPEG-2 will yield a better-looking video picture in most cases.
How does this streaming thing work?
To stream media via the Internet you first need the video/audio in digital format - this is where video capture cards play their role. Next you must compress that media with an encoder so it can travel efficiently over the Internet. And lastly you need a server to send the media to a player/browser upon request.
The first part of this magic formula is video compression. To compress video, a complex mathematical formula breaks the individual frames into moving and static components. Then it takes each moving object, and guesses where it will be for the next frame. By refreshing only the moving components, and recycling the static images, compression reduces the size and speed of the video file. There is a downside to compression.
If the camera is panning, zooming, or moving in any way, the whole image is in motion, leaving nothing to recycle. This leads to poor compression, and a slower transmission. Click here for more techniques of shooting videos for streaming.
The second part of the streaming combination is buffering the file. By giving the file a few seconds to load before starting the image, a reserve of video is available in the memory of the client's computer in case the transmission slows for a moment. When the transmission slows, the client computer uses part of the reserve of video.
All of the packages work similarly. To view video, the surfer needs only to download the viewer or browser plugin, most of which are free, and install it on his computer.
To actually netcast videos, you would need to purchase software to encode your digital video into the streamed format. Then, you would need to get a streaming server. Some programs use a standard web server, while others need special streaming only server.
How do I view streaming media on my computer?
You have to download and install a streaming media "player" that decompresses the files when they get to your computer. These players can be downloaded for free onto your hard drive from a few different vendors.
What are the most common streaming video players?
All three players are viable options for viewing streaming media, but RealPlayer has begun to dominate the industry as it is the most widely used player on the market.
What are the differences between different companies' streaming media formats?
RealNetworks, Apple and Microsoft's competing formats have much in common. They all use specialized, proprietary codecs (compression / decompression algorithms) to encode and playback their streaming media.
They all release occasional updates in the form of advanced codecs (which usually produce better-looking video at lower bandwidths). Many critics may tell you that Windows Media is "jerkier" but "crisper" and that RealVideo is "smoother" but "blurrier" or even vice versa. Tthe point is, they're all very similar and all currently enjoy widespread worldwide distribution and recognizance.
Perhaps the biggest differences are their costs: Windows Media is "free" to encode and serve (but you must use Windows OS, of course); QuickTime server support is strongest on a Macintosh platform and may involve a cost to encode (using QuickTime Pro); RealNetworks has sometimes hefty costs associated with large servers.
How to choose the best streaming format?
For your videos to be viewable by the widest audience possible, you may have to offer it in at least two of the three major formats and at 3 different bandwidths - 56k and higher. It is a waste of your audiences time to create streams based on anything lower then 56k. If they can't get on the web at 56k, then your audience is not ready for streaming video.
If you want your video to look good over a 56k modem, you have to pick what you are willing to sacrifice and how much of it. The first thing is that you reduce the frame rate to 15 fps. The next thing you'll need to do is shrink the overall image size. The thing you want to maintain as best as possible is the overall image quality. At 56k your audience expects the video to be less smooth. But if it is jerky, tiny and blurry, they will not be coming back for more.
More details on the threemost common video streaming formats
Windows Media Player
Where to use video streaming?
Imagine owning your own broadcast network? Now anybody with a couple thousand dollars can get their live broadcast out to the whole Internet, a mass medium for the masses.
The new technology will also provide a medium for anybody who has an idea to share. Soon there will be Webcasts of shows for every possible interest. Anything from home cooking shows, to fly tying, to video editing will have its own dedicated aficionados sharing their knowledge through video.
Businesses can add video to their websites, or they can use the technology to use video over a WAN. Imagine the appeal for a tropical resort owner to show a live video feed of his sunny beach. A brewery could show you their brewhouse, with a Java script giving you a listing of exactly what was happening as the brewer pressed buttons on his control panel.
Live video isnít the only thing to use streaming. Any industry could use video on demand to showcase their products, events, and news conferences. A video clip could be incorporated as a click through into a banner add on another Web page.
Independent movie makers could use the technology to showcase their films, providing previews, or perhaps even allowing potential investors for a film to watch the dailies, as a bonus, in hopes of attracting many smaller investors.
And much much more...
How to choose the encoding parameters?
While encoding videos into the streamable format, you have to choose exactly how you want it compressed. Normally there are three parameters that make up the streaming quality of a video: frame rate, color depth, and resolution.
Frame rate is the number of still images that make up one second of video. 30 frames per second is considered full motion video for NTSC, 25 for PAL.
When a video is encoded to a frame rate of less than fifteen frames per second, it becomes noticeably jumpy.
Color depth is the number of bits of data the computer assigns to each pixel of the frame. 8-bit, 256-color video is very grainy and unsuitable for video. The 24-bit color is optimal, but because it greatly increases the size of the file to be streamed, you'll want to settle for 16-bit color if you plan on streaming video to viewers connected through the telephone.
Resolution in digital video is measured in number of pixels. For example, if your video is at 640x480, you have 640 pixels across each of the 480 vertical lines of pixels.
Video to be streamed over the Internet ranges from postage stamp video at 49x49 to160x120, all the way up to 640x480 and beyond. The default size (160x120), a larger size for shared broadband (240x180), and a full size picture for high-bandwidth viewers (320x240).
Some of the streaming programs will automatically set the color depth, frame rate, and resolution to match a certain connection speed. If your streaming software supports this, always set your target speed a little bit slower than what the connection is supposed to be at. That way, if there is latency on the Internet, and there will be, your viewers won't have as many pauses as the video is streaming just a little bit faster than the modem can receive the data.
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