Live video broadcasting

A video stream that is being broadcasted in near realtime on the net is called live video broadcast or live video feed. Live video can be broadcasted on the internet through a real time protocol by a streaming media server. Live video broadcasting allows an experience similar to TV or satellite broadcast. Another term for live video broadcasting is online TV. The main emphasis of this technology is time synchronization. As with satellite TV there is always a slight delay with live internet video due to network delays and stream processing(replication).

Common usage includes:

• live video chat
• webcam publishing
• online TV channels
• web based reality TV shows

In this article I’ll be speaking of live web video through Flash based technologies, which are the most popular at the moment. The Microsoft model is similar in concept.

There are the following elements in a live streaming scenario:

1. A stream publisher – that will provide the initial video stream
2. Media servers - that will replicate and retransmit the video stream. Realtime transcoding and processing is also possible.
3. A Player – that will connect to the media server and play the replicated live stream.

A single server can sustain a certain limit of connections to it. With the flash media server model there is a connection per user (player) and there is a need for stream replication. Stream replication works like this: A server provides a certain number of connections. If more connections are needed additional servers connect to a parent one and add more connections to the pool.

Pros of Live video compared with on-demand

1. It is LIVE! i.e. in real time.
2. No need for storage.

Cons of Live video compared with on-demand

1. Cannot be managed as content or indexed on the internet
2. Cannot use complex encoding protocols and tools, which leads to lower quality for the same bitrate (user connection)
3. Harder to scale as the model is more complex and demanding