What is streaming?

Streaming is one of those buzz words that many use but few understand. Plainly, it is the “live” or “just in time” delivery of data over a network (internet/web) and is mostly associated with audio and video media. The confusion comes from people misunderstanding the difference between “downloading” a file and “streaming” a file. Let’s see if I can help clarify…

To understand what streaming is, think of your TV. When watching TV, you are getting the audio and video as it comes from the source. Since the programs are not stored in your TV, you can not watch them again unless you tune in again. This is the same with streaming media. When watching a stream, the movie is not downloaded to your computer. It is displayed as it comes from the source (eg. a server) and then discarded. Your computer does not retain a copy of the movie. In order to watch again, you must tune in again.

Like TV programs, streams can be “live” (like a newscast) or stored (like a sitcom re-run). A live stream would originate from a video camera (or other input source) and be broadcast (streamed) live as it is happening to your computer. Just like an “on-the-scene” newscast, you are seeing everything as it is happening. A stored stream is media that has been prerecorded and sits on a server (or other source) waiting to be streamed to your computer.

The alternative to streaming is waiting for a movie to download before it can be viewed. This is similar to watching a DVD. Since you have a copy of the movie, you can watch it, pause it, rewind it, etc. This can be a big advantage, however, going to the movie store to rent a DVD can also be similarly annoying to waiting for a movie to download.

QuickTime offers a third alternative somewhere in between streamed and downloaded media called “Fast Start” movies. Fast Start movies are downloaded but can be viewed before the entire movie has been downloaded. This can be very cool and is better than waiting for the entire movie to download but it is NOT streaming. You are still downloading the file and it is still stored on your computer, you can just watch it while it’s downloading.

Why not always stream?

There are a number of issues to consider when streaming media.

- Bandwidth is still the largest obstacle to overcome when choosing to stream media. In order to stream a movie effectively, your clients (people watching the movies) must have a faster connection (eg. internet connection) than the movie is being sent at (encoded bit rate). A 100kb stream will look TERIBLE to a user on a modem connection (56kbs). My personal opinion is that streaming video at modem rates (56kb) is pointless and never looks good. However, audio only streams can work rather well at modem rates.

- Bandwidth is expensive! How much do you pay for your connection to the internet? To stream movies you must have enough bandwidth for all of the clients connected For example: If you have a T1 line (1.5Mb or 1,500kb) you could probably handle about 10 clients each watching a 100kbs stream (technically, it’s more like 15 but due to network traffic, it is best to have some headroom). If you only need to serve 10 clients you might be okay.

- But… getting back to our TV analogy: With TV, the more clients (people watching), the better. The more popular their shows, the more money they make. It costs them nothing when someone else tunes in. With streaming, everyone that joins the stream costs you more money (Bandwidth usage). It’s a difficult sell…

-Better Codecs are needed to improve audio and video quality in addition to lessening the bandwidth usage (making files smaller).