Screen Share Understanding Bandwidth and Resolution

What factors are involved in sharing?

The information listed below is a technical explanation explaining factors to consider when screen sharing. Before reading the content below, Jigsaw recommends the resolution for the sharer to be no greater than 1280 x 720. If that is too large for your audience, then step down to 1024 x 768.

 

The two most important factors are: Available Bandwidth and the Resolution Being Shared.

Available Bandwidth

If you imagine your Internet connection as a “pipe”, then the Upload/Download speed of your connection determines the size of pipe that your data flows through. The bigger the pipe, the more data can flow through it. If you have a 1 Mbps (megabit per second) pipe, and you are trying to push 2 Mbps of data through it, then much of the data will not make it to the other end.

 

 

The bandwidth of all Attendees in your session must be considered, because if you are sending “fire hose” sized data down to a “garden hose”, then the receiver (Attendee) will either choke from the overload or Jigsaw must change what you are sending into a size and level of detail that the Attendee can handle and display. This can result in a “pixelated” view, choppy movement, slow transitions, etc.

Available Resolution

This represents the “amount of data” that you are trying to send through your pipe. “Resolution”, for our purposes, means the “size and density of the area being shared”. The larger the screen and the more dense the pixels, the higher the resolution.

In the image below, you can see that a person sharing a full desktop from a 27-inch iMac (with retina display) is sending an extreme amount data to all Attendees. In fact, you are sending over 14 million pixels (bits of data) through your pipe, and into the pipe for each Attendee, which is then trying to display the data you sent, on their own screen. The laptop running the “most common” resolution (1,024 x 768) is only capable of displaying less than 1 million bits of information at a time.

 

How can you fit over 14 million bits into less than 1 million? You can’t. So, Jigsaw attempts to “downsample” what you are sharing so that it can be viewed by each Attendee. This will result in a very fuzzy (pixelated) view, for the Attendees.

Given this information about Bandwidth and Resolution, what can I do to ensure that what I am sharing looks good and updates quickly for all Attendees?

 

Know your Bandwidth

The first thing you should know is the size of your Internet pipe. This information would come from your own ISP (Internet Service Provider) or from your internal tech support.

 

You actually have 2 pipes (or speeds) to consider for your bandwidth measurements:

  1. Download – This pipe determines the amount and speed at which you are able “receive” data coming to you. If you are watching someone else’s shared screen, or webcam, or anything else that you are receiving from others, this is using your download pipe.
  2. Upload – This pipe determines the amount and speed at which you are able to “send” data to others. If you are sharing your screen, your microphone, your webcam, etc. all of this data must go through this pipe. Note: Your “upload” pipe/speed is almost always much smaller/less than your “download”. For example, if you have a 5 megabit download speed, you probably have less than a 1 megabit upload speed. Internet providers may shorten this to read something like: “5mb down/1mb up” or even “5 down/1 up”.

No matter what speeds you think you are getting, it is always best to actually test! You can go to any number of speed testing sites, like http://www.speedtest.net/

Once at the site, click the “Begin Test” button.

When the test is complete, your speed will be reported…

 

Understand that your speeds can vary widely depending on many factors including: time of day, day of week, others at your same location using the Internet, automated backups, running virus scans, your operating system downloading updates in the background, the other applications you have running on your computer, etc.

Typically, any person’s upload speed will only be 30% (or less) of their download speed (the example above shows an upload speed that is only 9% of the download speed). However, if you ask someone the speed of their internet connection, they will almost always give you their download speed, and most people aren’t even aware there is a difference. Knowledge is power!

Note that your “Ping” rate is also being recorded. This is simply a measure of how quickly one single bit of information can travel from your computer to the destination. This number should always be less than 50ms (milliseconds). If this number is high, then there are either too many junctions to cross or there is a bad piece of equipment at one of those junctions.

If your Ping is 50ms or above, or your Download/Upload speeds are lower than you were promised by your Internet service provider (ISP), you should contact your provider immediately, because you are not getting what you are paying for!

Know your Resolution

Understanding your computer’s “resolution” will help you determine how much data you are trying to push (upload) through your pipe, into the pipe and to the desktop of each Attendee.

On your Windows computer, right click on your desktop and choose Display Settings.

On a Mac, click the “Apple” in your menu, choose System Preferences, and then select Displays. Your currently selected resolution will have a “blue” border around it. You may need to “hover” over the display choice to have the actual resolution show (under the picture of your Mac):

 

 

Once you know your Upload/Download speeds (your bandwidth) and your screen Resolution, you can make better decisions about how you use the Internet in general and Jigsaw specifically. There is no “fix” or “magic bullet” for poor bandwidth or for trying to push a firehose amount of data through a garden hose.

 

Recommendations

  • The more resolution (data) you send to participants, the smaller it will look for them (and there is a higher probability that you will lose colors and clarity), which basically means “the more your share, the worse it will probably look”. Try to make the area you are sharing most closely match the area (resolution) available on the screens of other participants.
  • The more resolution (data) you share, the more bandwidth will be needed by both you and other participants. Even if you have a large pipe, others may not, and this will make the experience of viewing what you are sharing much more painful for them.
  • Application Sharing is better...
    - Higher quality viewing experience for participants.

    - Lower upload bandwidth needed for you.

    - Less download bandwidth needed for participants.

    - Less confusing for participants.

    - Your “desktop notifications” (e-mail, text messages, reminders, etc.) cannot be seen by participants.

    - Will help overcome differences in screen resolutions between you and other participants. If you size the Application you will be sharing, so it only takes up part of your screen, you can avoid sending across your entire screen resolution. For example, if the Application you are sharing is resized to fill 1/4th of your screen, you will only be sending 1/4th of your total screen resolution to other participants. This will make everything easier to see, more responsive, and will enable more people to share more things in the session.

    *Just make sure you resize the Application “before” you begin sharing.
  • If you do need to share your full desktop, it's best to set your monitor to a reasonably low resolution (1024x768 is recommended since this is the most popular resolution) before you begin sharing. Even if everyone in the session is using a resolution of 1920x1080 (which is very popular), remember that your entire shared desktop must still fit within the bounds of the Sharing pane inside the Jigsaw application space.

 

Mobile Devices

 

ALL phones and tablets are considered “mobile devices”. If you have participants joining your session on an Apple/Android tablet or an Android phone, this will have a big impact on your sharing considerations.

Most mobile devices actually have a better screen resolution than most computers/laptops. This is the good news J. On the downside:

  • They can only use WiFi (or cell speeds) which are usually slower and more prone to disconnections than computers with network cables plugged directly in.
  • Typically have worse network performance overall.
  • Have less computing power (to be able to process all of the incoming live videos, audio, etc.). Even a low-end laptop will usually have much more computing power than an expensive tablet. A notable exception is the iPad Pro (2017 models and newer), they have as much or more processing power than most low-end or even moderate computers.

 

If you are in a session with two or fewer webcams, or a single desktop is being shared, mobile devices should not experience any issues, provided they are on a good WiFi (or even LTE) connection.

However, if your session has 4+ cameras or multiple desktop shares going on simultaneously, the mobile participant will likely face technical issues resulting in a poor experience.

Jigsaw has many guardrails in place to ensure everyone has a good and similar experience to everyone else. Jigsaw will prevent people from getting dropped from a sessions due to poor bandwidth or computing power. Jigsaw is constantly measuring your network/Internet performance as well as how well your computing power is able to handle what is being thrown at it. Jigsaw will downgrade or even stop video feeds if it detects a problem that would cause a dropout or even a severe degradation in the quality of the session audio (or the ability of the participant to stay “in sync” with everyone else).

 

Summary

You might be thinking that understanding the information in this document seems like work that you don’t want to do… that’s okay!! There is no requirement in Jigsaw for you to know any of this information or to make any changes to what/how you share. Jigsaw has gone to extraordinary lengths to make sure everything works well for everyone involved, no matter how much screen real-estate is shared or the bandwidth each person has. So, it is likely that you don’t need to know any of this. However, understanding at least the basics about the effects that Bandwith and Resolution have on the ability of other participants to clearly see what you are sharing in a smooth and seamless way, will only make your sessions more enjoyable, and most importantly, more conducive for learning!

Useful Information

Most Common Screen Resolutions

The most-used resolution is still 1024x768, but this is changing rapidly. Most computers support “Hi-Def” or 1080p, which is a resolution of 1920x1080. The chart below shows the most-used resolutions of “Steam” gamers (a PC Gaming platform) and regular Web Users. As you can see, the majority of “gamers" use a resolution of 1920x1080 or lower. But, 50% of normal “web users” use a resolution of 1366x768 or lower, with only about 18% using 1920x1080 or better.

 

 

These are very general numbers. If you work closely in Jigsaw with a small number of people, you could find out more about their general resolutions, and share appropriately.

 

Most Common Operating Systems

Why is this important? Well, you can usually make a good educated guess about someone’s screen resolution (and possibly bandwidth) simply by knowing more about their computer. For example, if someone is still using Windows 7, there is a much better probability that they will be running at a lower resolution (using older computer hardware) than someone running Windows 10. Typically, the more modern the computer and operating system, the higher the screen resolution they will have. The higher their resolution

 

The two sets of numbers below come from two different sources, but their overall numbers are close enough so that they don’t contradict each other.

 

 

 

 

Common Screen Resolutions For Macs

Apple controls all aspects of it’s hardware. This makes it easy to know exactly what hardware is in your computer and its overall capabilities. This is not true for Windows PCs and it is nearly impossible to come up with a finite list of possibilities.

 

MacBook (Retina, 12-inch, Early 2015) and later

2304-by-1440 resolution at 226 pixels per inch with support for millions of colors.

 

MacBook Pro (Retina, 13-inch, Late 2012) and later

2560-by-1600 native resolution at 227 pixels per inch with support for millions of colors.

 

MacBook Pro (Retina, Mid 2012) and MacBook Pro (Retina, 15-inch, Early 2013) and later

2880-by-1800 native resolution at 220 pixels per inch with support for millions of colors.

 

iMac (Retina 4K, 21.5-inch, Late 2015)

4096-by-2304 native resolution with support for millions of colors.

 

iMac (Retina 4K, 21.5-inch, 2017)

4096-by-2304 native resolution with support for one billion colors.

 

iMac (Retina 5K, 27-inch) displays from 2014 and 2015

5120-by-2880 native resolution with support for millions of colors.

 

iMac (Retina 5K, 27-inch, 2017)

5120-by-2880 native resolution with support for one billion colors.

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