Streaming Video Concepts ~ Vinay's Blog

Dec 26, 2009

Streaming Video Concepts

STREAMING

Streaming is a technique for transferring data such that it can be processed as a steady and continuous stream. Streaming video is a term applied to the compression and buffering techniques that allow one to transmit and view video in real-time through the

Internet. In other words, streaming media is the simultaneous transfer of digital media files such as video, audio, and data through a server application that can be displayed in real-time by client applications. Once a streamed file has been downloaded and viewed, the physical file is no longer present on the user’s computer or Mobile Devices.

When creating streaming video, there are two things you need to understand: The video file format and the streaming method.

FILE FORMATS

There are many video file formats to choose from when creating video streams. The most common formats are:

Windows Media
Real Media
QuickTime(It represents the .qt and .mov file formats)
MPEG (in particular MPEG-4)
Adobe Flash(It represents the .swf and .flv file formats)

STREAMING METHODS

There are two ways to view media (such as video, audio, animations, etc): Downloading and streaming on the internet.

DOWNLOADING :

When you download a file the entire file is saved on your computer (usually in a temporary folder), which you then open and view. The easiest way to provide downloadable video files is to use a simple hyperlink to the file. A slightly more advanced method is to embed the file in a web page using special HTML code.

Delivering video files this way is known as HTTP streaming or HTTP delivery. HTTP means Hyper Text Transfer Protocol, and is the same protocol used to deliver web pages.

Advantage:

1. Quicker access to different parts of the file.

2. This is the simplest and cheapest way to stream video from a website. Small to medium-sized websites are more likely to use this method than the more expensive streaming servers.

Disadvantage:

HTTP streaming is a good option for websites with modest traffic, i.e. less than about a dozen people viewing at the same time. For heavier traffic a more serious streaming solution should be considered.
You can't stream live video, since the HTTP method only works with complete files stored on the server.
You can't automatically detect the end user's connection speed using HTTP. If you want to create different versions for different speeds, you need to create a separate file for each speed.
HTTP streaming is not as efficient as other methods and will incur a heavier server load.

To Create HTTP Streaming Video:

Create a video file in a common streaming media format
Upload the file to your web server
Make a simple hyperlink to the video file, or use special HTML tags to embed the video in a web page.
When a user clicks the hyperlink, their media player opens and begins streaming the video file. If the file is embedded, it plays right there on the page.

Streaming :

Streaming media works a bit differently — the end user can start watching the file almost as soon as it begins downloading. In effect, the file is sent to the user in a (more or less) constant stream, and the user watches it as it arrives. True streaming video must be delivered from a specialized streaming server.

Advantage:

The ability to handle much larger traffic loads.
The ability to detect users' connection speeds and supply appropriate files automatically.

The ability to broadcast live events.

PROGRESSIVE DOWNLOADING

Progressive download is also known as a hybrid method .In this method the video clip is downloaded but begins playing as soon as a portion of the file has been received.

THE TECHNOLOGY BEHIND VIDEO STREAMING

Before creating digital video for streaming purposes, the following factors should exist:

Create the video in the required encoded format.
Access to a streaming media server
Adequate bandwidth to download and upload the video file.
Hardware & Software for creating video streaming

Most streamed video comes in one of three popular formats: (a) Real Networks’ Real Media (b) Microsoft Windows Media (ASF or Advanced Streaming Format) and (c) Apple QuickTime. All three have specific advantages and support the Real Time Streaming Protocol (RTSP). To stream files created in these three formats, the video files must be placed on a streaming media server that has the server-side software to stream the video. In addition, that server must have enough capacity and bandwidth to support the number of simultaneous video streams by multiple users.

Other formats for streaming video are MPEG-2 and MPEG-4. MPEG-4 is a newer standard specifically developed to address Web and mobile delivery. MPEG-4 is backward-compatible with MPEG-2, a video compression standard used on billions of DVDs and millions of satellite receivers.

THE STREAMING PROCESS

For streaming to work, the client side receiving the data must be able to collect the data and send it as a steady stream to the application that is processing the data and converting it to sound or pictures. This means that if the streaming client receives the data more quickly than required, it needs to save the excess data in a buffer. If the data doesn't come quickly enough, however, the presentation of the data will not be smooth.

STEPS FOLLOWED IN VIDEO STREAMING

1. Digitally compress the audio and video content (This is required to conserve bandwidth that is used for the delivery of the content. Specially developed software applications, called codec, are used to compress the video and audio data.)

2. Load the encoded video and audio contents in the streaming server. (Streaming servers can be installed in the systems using special softwares.This special server software can be used for the continuous distribution of multimedia content in the internet. This specialized software can be installed and run on various computer operating systems including: Windows, Linux and Macintosh.

Individual files can be distributed using on demand content delivery, without the need for specialized server software. On demand content can be hosted using a standard website account.)

3. Prepare the compressed content for delivery (Delivery of this data over computer networks uses special software or hardware instructions to route the video and audio content to the end user. Methods of multimedia data transport include: HTTP, RTSP, IP Multicast and P2P.)

TO CREATE A STREAMING VIDEO FILE

There are two ways to create stored streaming video files:

Use a conversion utility program. This takes an existing digital video file and converts it into the streaming format of your choice.

Export streaming files from video editing software such as Adobe Premiere, Final Cut Pro, etc.

Conversion Utilities

A conversion utility is a stand-alone program which imports a video clip and exports it to a different format. Examples include Real Networks Real Producer and Sorenson Squeeze .Basically; you simply open a file and select which format to save it as. You can set various parameters to optimize the final video. Then select encode option to create the encoded video.

Exporting a File

Most serious video editing applications have options to export video for the internet. This is often the easiest way to create streaming video files.

Once you have created your streaming video file, upload it to your website. It doesn't matter where you put it as long as you can access it from a web page. For example, you might like to create a folder caller "media" or "video" and put all your video files there.

STREAMING SERVERS

A streaming media or streaming video server is a specialized application which runs on an Internet server. This is often referred to as "true streaming", since other methods only simulate streaming. True streaming has advantages such as:

The ability to handle much larger traffic loads.
The ability to detect users' connection speeds and supply appropriate files automatically.
The ability to broadcast live events.

There are two ways to have access to a streaming server:

Operate you own server (by purchasing or leasing)
Sign up for a hosted streaming plan with an ISP (Internet Service Provider)

Operate your own server

To run your own streaming server, you can either purchase a standalone server machine or purchase streaming server software package or install it on an existing web server. Streaming software is available for all common server platforms such as Linux, Windows, etc. Some examples of streaming media software:

Helix Universal Server from Real Networks. This server supports a variety of formats, including Real Media, Windows Media, QuickTime and MPEG-4.
Apple QuickTime Streaming Server, supporting a few formats including MPEG-4 and 3GPP.
Macromedia Communication Server, specializing in Flash-based video and interactive multimedia.

Sign up for a hosted streaming plan:

In much the same way that you sign up for a website hosting plan, you can get yourself a hosting plan which specializes in streaming media. This is a far more realistic option for most people.

Some examples of hosted streaming media plans:

(i) Real Networks Managed Application Services (MAS)

(ii) Apple QuickTime Streaming Services

(iii) Macromedia Communication Server Hosts