Mobile Webcasting

I’m handy with computers and software, but allergic to audio-visual gear. Faced with a balky projector or microphone, I always hope a nearby AV will perform the laying on of hands. But now I’m going down the slippery slope. It’s all Apple’s fault.

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For starters, the combination of Mac OS X, the iSight camera, and iChat AV delivers stunning results. Even without the camera, using just the internal microphone, you can enjoy Mac-to-Mac Internet telephony with reasonable quality and latency. When both ends are camera-equipped, you can have a surprisingly effective point-to-point videoconference. The connection works even when one or both parties are behind a NAT or firewall, thanks to a connection-splicing feature that Windows Messenger lacks.

Still, the universe of people who run OS X, own an iSight, and use AIM or .Mac — the only two IM services available for call setup — is not large. There was a flurry of interest in iChat AV when it first appeared this summer. When the novelty wore off, the consensus was that it’s great for

Mac-equipped groups of friends and family, or business associates, but it can’t create serious network effects.

There matters stood, for me, until last week when I looked into what other use I could make of the iSight’s video stream. I downloaded a copy of Apple’s free QuickTime BroadCaster, an encoder that can record and send a stream. You need a streaming server to catch and broadcast the stream you send, so I went back to Apple’s site to download Darwin Streaming Server (DSS), the open source version of the QuickTime Streaming Server included in OS X Server. DSS runs on lots of platforms; I installed it on Windows Server 2003.

To broadcast a stream, you point QuickTime broadcaster at DSS, export an SDP (session description protocol) file from QuickTime BroadCaster, and place it in the streaming server’s Movies directory. To view the stream, launch QuickTime Player and load a URL like rtsp://dss_host/broadcast.sdp. Once I got this working I moved the server to a second DSL circuit in my lab. I configured the firewall to allow TCP ports 80 and 544, and UDP ports 5432 and 5434. And amazingly, it all worked. From my TiBook on one Internet-connected private LAN, I was streaming video to a server on a different Internet-connected private LAN. That server’s broadcast was available — at an eight-second delay — to any QuickTime Player on any platform anywhere on the Internet. What’s more, the TiBook could be sending the stream from any Wi-Fi-equipped meeting or conference, anywhere on the Internet.

To those of you who are AV geeks, this comes as no surprise. To me, however, it was a revelation. The acid test, of course, will be to share an event with distant colleagues in near-real time. Kevin Marks, a former member of Apple’s QuickTime team, recently did that from the front row of a session at BloggerCon. At the time, I wondered how he did it. Now I know.

The eye-opener, for an enterprise that isn’t about to make a wholesale switch, is how little Mac gear you need: one OS X notebook, a camera, and QuickTime Broadcaster. Run the streaming server on a Linux box in your DMZ (demilitarized zone); send a TiBook-toting emissary to any Internet-wired or Wi-Fi venue; watch and listen from your Windows desktops. It’s easy, it’s cheap, it works like a charm.