Introduction to streaming media
Streaming versus downloading
You can provide a media file to students in either of two ways:
- As a download – students open or save the file to their desktop. Download/opening speeds will be dependent on file size and bandwidth. Delays can be significant.
- As a streamed file –- the file will begin to play as soon as data begins coming in. Smooth, uninterrupted playback is bandwidth dependent.
What is a streaming media service?
A streaming media service (SMS) broadcasts multimedia presentations over the internet (or an intranet) to individual users. The multimedia content may be music, audio, video/audio, and slideshows with audio etc. Multimedia files are typically large and require significant bandwidth for reasonable use. An SMS specialises in providing data streams that maximise the balance of quality and speed for the user.
The key hardware/software requirements are:
- A streaming media server with dedicated streaming media software.
- Users require media 'player' software on their PC to receive and view the multimedia content.
The Lectopia system currently provides these services for teaching at UTAS, for more information go to the Lectopia website http://www.utas.edu.au/itr/lectopia/.
The server perspective
Multimedia content is sent to the user by a streaming media server, which has software dedicated for this purpose. The server can efficiently broadcast multiple presentations to multiple users concurrently – depending on network infrastructure and server load. It uses specific protocols and methods that are dedicated to multimedia presentations, which greatly enhance speed, accessibility and quality. In addition, no files are stored on the client's computer.
Ordinary web servers can also broadcast multimedia files, but they do so very inefficiently. When a file is requested by a user it is downloaded in full and stored on the client's computer. The server has very little control over how efficiently this takes place. Web servers are unable to efficiently handle multiple users accessing the same multimedia file at once.
The client (user) perspective
Users operate dedicated player software on their computer. This software needs to be compatible with the multimedia format that the server is sending. There are a number of common formats in use – see Streaming media: Major formats. Players are generally free, relatively easy to install, and simple to operate.
Players and streaming servers intelligently negotiate the best quality stream, based on the speed and condition of the network at the time. This is handled in the background without any need for user intervention. Therefore, it is possible that a user with a very slow modem can still access a reasonably consistent stream, at a quality that is reasonably acceptable. The software also ensures fairly smooth and uninterrupted streaming.
Developers do not have to produce multiple copies of their multimedia files to suit different combinations of quality and speed. They simply produce a file compatible for typical use (based on the intended users) and the server handles all of the speed and quality adjustments from the single file, in real time. In this way, many users could be accessing the same multimedia file at once, but the server is sending them different quality streams to suit their individual conditions.
Key advantages of using SMS
- Intelligent and efficient broadcasting of content – regardless of the type and speed of connection.
- Generally, streaming produces transmissions of higher quality and speed.
- The presentation will begin to play before all the data is received.
- Minimal waiting time and pauses for the user.
- Users have more control over the presentation and can navigate within it.
- Typically more reliable and responsive for users.
- Ordinary web servers are freed up to perform their function, and general network congestion is reduced.
- Multimedia files are protected. Files can be made to stream only and are not downloadable by the user.