Internet Speed and Your Webcast

What You Really Need to Know about Internet Speed For Streaming Video:

Its common knowledge (or should be) that the speed of your internet connection is crucial for webcasting through any online streaming service. This applies both to your upload speed (the rate at which you can transmit information out) and your viewers’ download speed (the rate at which they can pull in and view the video you are streaming).

There are a lot of myths and false notions floating around the world wide web regarding the value of Internet speeds. Naturally your ISP (Internet Service Provider like Telus, Shaw, Rogers, etc.) will always provide you with a best-case figure when it tells you what your upload or download speed is, which is not always what it really. In reality your effective speed depends on a number of variables that you may be unaware of.

Myths and information about Internet speed for streaming video get tossed around as common knowledge and while some of these ideas are true, many others are not.

You need to know if you have sufficient Internet speed to broadcast smoothly without any glitches – in order to do this you need to understand how it all works. Here are some critical factors that will affect your Internet speed and subsequently the efficiency of your broadcast…

Internet Speed Ratings and Actual Speed:

Your ISP usually advertises the speed rating for your particular plan, but that is rarely your actual speed. It’s actually just the maximum capacity of your connection, which goes up and down (usually down) minute to minute depending on a number of factors such as heavy traffic, etc. You can’t browse or upload faster than your speed rating, but most of the time your actual connection will be slower.

Your actual speed depends on the slowest bandwidth anywhere along the line of the number of connections between the source to end user, which in turn depends on a number of factors, including distance, crowding of the channel by other users or other networks (usually heavier or lower at certain times of the day) the TCP window size, network latency, and whether you’re on a hardwired connection or using wireless.

Physical Factors: Distance, Other Users, Other Networks

The way a signal moves from one computer to another over the Internet involves a series of hardwired and wireless connections. Each step of the connection has its own maximum transmission speed. The slowest of these connections is what determines your actual connection speed between your broadcast and your viewer’s device.

Your upload speed rating is only one of those factors. Many of them are not under your control at all. A few factors are, though. These include the distance between your computer and your router if using a wireless connection, and also how many other users are on your network and how many other networks are in range of your computer or your router. Your performance is likely to be reasonably good as long as all of these factors are within reasonable limits, but drops off quickly after that.

Latency:

Network latency (more commonly known as delay) is one of the biggest roadblocks between you and your theoretical Internet speed. The term refers to the time it takes for a signal to go from source to destination and is measured in milliseconds (ms). It’s affected by the route that the signal takes ie. how many computers or networks it travels through before reaching the viewer’s download device) and also by the physical distance traveled. Imagine an oil or water pipeline. It will obviously take longer for the fluid to travel a hundred miles than it will to travel 10 miles. The same principle applies here.

Latency is one common reason why a page sometimes takes a long time to load. It is also the reason why a video being broadcast will end up being delayed about 5 seconds or more as it is being broadcast.

Most streaming devices use buffering (ie. collecting and storing data as it streams, to be used as a backup in case the delay is too great. A high latency can be temporary or persistent. Temporary latency can often be corrected by the buffer or if the network signal can be redirected to a shorter route, the latency decreases. Persistently high latency represents a problem with the network, which is more common with Satellite networks.

Latency of a system can be tested by using a ping test. Remember that latency occasionally spikes, so several tests over time give better information than a single test. For broadcast purposes, you want your network to have a consistent latency of 100 ms or less, and the lower the better.

TCP Window Size:

The TCP window size is the amount of data that is transmitted by a computer before it sends a signal asking for acknowledgement and waits to receive a response. You’d think that increasing the window size would always improve performance, but that’s not the case. To start with, TCP window size isn’t a unilateral decision by one computer but an agreement between the two electronic parties to the conversation. Each such request uses some connection capacity itself, so it’s possible to slow things down with a larger window size rather than speeding them up. TCP window size should be adjusted for the bandwidth and latency. Higher connection speeds and higher latency both allow or require a larger TCP window size. Shorter latency connections (which you want) are optimized by a smaller TCP window size.

Wireless vs Hardwired Connections:

As all of the above suggests, the connection between your router and your computer is only a small part of what determines your actual upload speed. A chain is as strong as its weakest link, and your connection can only be as fast as its slowest segment.

Very often that slowest segment is the connection of your computer to the router. All else being equal, there’s no doubt that a hardwired connection is faster than wi-fi. It also allows for greater security and reliability. However, don’t expect a hardwired connection to increase your speed much if the bottleneck lies somewhere else along the chain. Going wired is a must, especially if you’re using a slow connection. These days hotels provide fast connections, especially if you request one in advance.

Here’s a method to determine the bandwidth and Internet speed for any given connection. Use any online speed testing service such as speedtest.net and carry out a test, which will show you the upload and download speed as well as latency in your system and the Internet connection. Other free programs offering online services such as Pingtest will help you see where or if there is any holdup at any one of the stops along your broadcast chain.

Making sure you have sufficient Internet speed is one of the critical factors in determining the efficacy of your broadcast and one that can make all the difference between success and failure of your event.