If you have ever set up a live stream its a question you may have asked yourself. Or you may not as Facebook, Instagram and countless other platforms make it so easy to go 'live' from your mobile device without considering the technicalities.
If you have thought about it the obvious conclusion would be that, if your internet connection is up to it, 1080p (or Full HD/FHD) is the option to choose. You may have also seen that some cloud based services such as only offer 720p (often referred to as HD) as the maximum resolution. The reason for this is down to the many moving parts of the broadcast signal chain.
Any system is only as good as its weakest part, the weakest link in the chain. So in a simple live stream you will have;
Camera > Encoder > Internet connection > Service Provider > Playback device
For Many the Camera and encoder are bundled together in a laptop or mobile phone. The cameras on these devices have improved significantly in recent years, particularly on mobile devices. Laptops have been a bit slower on the uptake and we also tend to hold onto laptops for longer meaning that they may be a few years older than our shiny new smart phone. No matter how good your camera is, if you are using a web browser to connect to your streaming service you will be using the WebRTC protocol. The most common implementations of this framework limit the video input to 720p (there are some exceptions). If you use a separate application (including specific mobile apps) then you may be able to increase the resolution to 1080p.
ZOOM - for all standard Zoom packages the limit is 720p. According to the Zoom Help Centre "Full high definition video, 1080p, is limited availability for Business and Enterprise plans."and these will have to be activated by the Zoom support team.
The real answer to the question is one of internet bandwidth. This is not connection speed and there are many articles written about this. There is also your network environment to consider. A speed test may give a fast down and upload speed result, but this is based on relatively small downloads and uploads. Over the course of your live stream your network may have management rules that may prioritise other users or protocols (such as voice calls). So what can you do?
- If you are using a network that has an IT manager, talk to them to discuss any potential issues.
- Run a speed test from your encoder (if available) this should then suggest the best setting based on the available connection.
- Think about this is good time - do not leave it until 2 minute before going live!
- Think of your audience. Will they mainly be on mobile devices or desktops? Small mobile screens, whilst having high resolution, will not be large enough to show a noticeable difference between 720p and 1080p
So there is no clear cut answer to which resolution. Ask yourself this; what is best - a full bit-rate 720p feed (full fat!) or a reduced bit-rate 1080p feed (semi-skimmed)? The reduced bit-rate 1080p signal, whilst showing as a higher resolution, will not have the same depth of information that the full bit-rate 720p signal meaning that the 720p image will be perceived as being of a better quality.
For those of use brought up in the 1970s/80s there can be only one answer!