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I watch live cricket matches online. Note that the match is held LIVE (somewhere!). At times since my Internet connection is slow, my video starts to buffer.

Let's say my video stops playing and struck when a batsman is hitting for a six. After some time when the buffering has finished, the video resumes playing exactly where it was stopped (in this case, when the batsman hit a six). However, this is a LIVE match so evidently I'm not really receiving it LIVE.

It seems like the server is maintaining a queue and whenever it buffers, it waits for the buffering and starts from the place where it had stopped. What actually goes on when a video buffers?

Is the video streaming technique the same for sites like YouTube (where the videos are already stored) and also for sites like online video coverage sites?

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up vote 3 down vote accepted

I am sorry to reveal to you that you never receive a live broadcast in real time.
And the reason is the buffering.

In essence, during the "Buffering..." stage, the player is building a buffer of x number of seconds. It will only start playing when the buffer is full, or if the source is slow then it may decide to display whatever it has.

This looks like :


The top arrow illustrates the playing and the bottom one the filling of the buffer. The 5 seconds is an arbitrary parameter.

The player in this example will catch up to any streaming delay of up to 5 seconds. If the delay is longer than 5 seconds, the existing partial buffer will be discarded, and a new buffer will be started from the "live" source. When incoming data continues, it is added to the buffer and presentation continues smoothly, even though packets might have been received in the wrong order and at different times.

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Actually you can make it as LIVE as POSSIBLE. With Flash Media Encoder and a Flash Media Server and all buffers turned down you can get down to 0.5 seconds of latency! In this case it will try so hard to keep up with the live event that it stutters if the connection is too slow. – sinni800 Aug 16 '11 at 14:14
It's a trade off that server admins and content providers must choose. Most people would rather be delayed 5, 10, 15 seconds if it means they get to see the game relatively smoothly. Some people (if the interest is more about gambling than the sport being viewed) want the absolute quickest and most real-time view. And then there's the broadcast delay (at least here in the US) where everything is delayed 3 seconds anyway to allow audio to be muted if an expletive is uttered into a live mike. – music2myear Aug 16 '11 at 14:49

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