Real-time Video Streaming

We have talked about multimedia streaming in PCQuest before. But most of the times we looked at streaming content from a local storage–the content was captured, encoded and stored on the local hard disk and then streamed over the LAN or the Internet. But what about real-time streaming of video while an event is happening?

What you need



You need the following: a camera (a camcorder or one that gives you S-Video or Composite video output; even a webcam would do but for its video quality), a video capture card and an encoding/ streaming application. 

You would need to wire the camera to the capture card, install the requisite drivers, before you can start streaming. Test the camera setup by running the card’s capture application. If your capture application records audio from your sound card, you’d also need to wire the audio from the camera (or any other source, like an external microphone) to your sound card. Try capturing some video onto your PC to check if you are getting both video and audio to a file. Once satisfied, set up the streaming server. 

Using RealServer



You need two tools to stream your video in real-time in the RealMedia format: RealProducer and RealServer. While the first converts audio and video files or a live source data into streaming media content (RealMedia), the latter is the streaming server. 

RealProducer works with wizards to guide you through the process of configuring the application to start broadcasting content from your capture source to a RealServer. The interface is simple with two video windows, the one on the left being the input video while the one on the right being the encoded output during a session. An audio level indictor shows the level of the audio track. 

The details of the final RealMedia stream like clip information, target audience (based on the connection/bandwidth), video quality and the type of stream are displayed in the middle of the interface window. Buttons to Start, Stop and Play your encoded clip are at the bottom. Of the three recording wizards, we would use only the one that is relevant to us–broadcast live, streaming content using

RealServer. 

This wizard guides you through the steps of defining your video and audio input sources (your video capture card and the sound card, respectively), the details about the target audience and the details of the RealServer and port you will be broadcasting to. Once through with the wizard, just hit the Start button to start the session. This will take the live content from your video and audio capture device, encode it onto RealMedia format in real-time and send it to a server for streaming over the network or the Internet. 

Remember that you’ll need to have RealServer Professional version to be able to broadcast content. The Basic version does not have the license to broadcast, ie, it would not accept broadcast requests from your RealProducer application. 

Using Windows Media Encoder



Microsoft has a lot of tools that let you work with streaming multimedia content. This includes a host of tools for indexing (ASF Indexer), encoding (Encoder) and making streaming image-with-audio presentations (Media Author). Our discussion will be limited to the live streaming part of the tools. 

Windows Media Encoder (now in version 7.01) allows you to directly capture video from your capture hardware and stream it. The interface is similar to RealProducer. It also has preview video windows for input and encoded output. The application is wizard driven. Start the application and select ‘Broadcast a live event from attached devices or computer screen’. The following dialog boxes take inputs for the capture devices for audio and video. You can configure the devices through here too. Specify a port for the broadcast and a streaming profile to use. Streaming profiles essentially define the target bandwidth, content compression and even broadcast type (NTSC or PAL). 

You can opt to archive a copy of the broadcast (saved as a Windows Media Video file locally). If a live broadcast is a regular feature you use (for some fixed monthly event for example), you can add a welcome and goodbye file to the stream. These would be added to your output stream at appropriate locations. The last dialog box takes in the stream information like title, description, author etc, and you are ready to go.

Hit the Start button to start you session. Clients will be able to connect to your stream using their Windows Media Player and your server’s reference URL and port over HTTP. 

With both the tools discussed here, you will need to experiment a little with the settings depending on the available bandwidth and other resources. The bottom line, however, is that tools are readily available to stream live video content and in case of non-interactive kind of video presentations; it does make sense to do it, rather than spend on travel, lodging etc. 

Ashish Sharma