Video in a Flash

To stream, or not to stream
I’m not going to go into detail about encoding options here, except to say that in most cases you’ll get the best results using H.264 and this is the only option if you want to deliver HD content. I’ve said plenty on the subject of encoding in general in past columns and, in essence, it comes down to making a size/quality trade-off that provides the best viewing experience given the viewer’s connection speed.

Having produced your .flv, the next decision to be made is how to deliver it. You can opt for either progressive download or streaming. Progressive is the simplest to implement and is fine for short clips on websites that aren’t going to get a lot of traffic.

A progressive download works like any other HTTP file request in that the entire video file is downloaded to the viewer’s PC. Playback of the movie can be started as soon as sufficient content is buffered. You don’t have to wait for the entire file to download. While adding a progressive .flv to a web page is straightforward, as seen in last month’s Hands On Web Development, there are some disadvantages.

Because the download is linear, you can’t skip to the end of the movie and watch, say, the last 10 seconds until the entire file has downloaded. And progressive downloading doesn’t afford any kind of copy protection. Savvy users can locate the cached file and play it back offline, add it to their own site, or breach your copyright in any other way that takes their fancy.

The alternative to progressive downloads is streaming. Setting up streaming delivery is more involved, but offers several advantages over progressive delivery. The most obvious from the viewer’s standpoint is that a streaming server can monitor the connection speed and vary the quality of the video stream.

Streaming also makes it possible to seek ­ that is, to skip back and forth to view portions of a movie without having to wait for the entire file to download. This is particularly useful for longer movies and for tutorial videos, where you might want to skip the introduction or go back over a segment. Streaming provides copy protection because the entire file isn’t downloaded to the viewer’s machine and, of course, if you want to webcast a live event streaming is the only option.

On the downside, streaming Flash video is more complex to set up and more expensive than progressive delivery. Flash Media Streaming Server costs £981.12 and runs on Microsoft Windows 2003 Server Enterprise Edition and Linux.

An alternative to buying Flash Media Streaming Server is to sign up with one of the Adobe partner content delivery network (CDN) providers for the Flash Video Streaming Service (FVSS). You can find a list of CDN providers at www.adobe.com/products/flashmediaserver/fvss/.

Flash Video Streaming Services aren’t confined to the Adobe partner organisations. Type Flash Streaming Server into your search engine of choice and you’ll find there’s no shortage of companies offering Flash video streaming. On-demand streaming is typically priced by storage capacity, with limits on monthly data transfer. As an example, flashstreaming.co.uk charges an annual fee of £499.99 for 1GB of space, with a monthly transfer limit of 50GB.