These days, it is easier than ever to live stream a house concert or live musical performance with a laptop computer and some decent audio-visual hardware.
Here is what you need.
1. A laptop or portable device with access to speedy Internet service via ethernet or wifi (ethernet may achieve better speeds than wifi, but most wifi is pretty fast nowadays), and which can be connected to compatible audio and video hardware. Make sure you have access to the venue's wifi.
2. Access to a free online live streaming app, such as Ustream or Youtube. You need to have a registered account with these apps to use them. Ustream is very user friendly and allows post editing and uploading to Youtube. Youtube is more cumbersome (this user's opinion).
3. A decent microphone that can interface with the device in #1, directly or via a digital interface (for example, the Mic Mate), and is compatible with the live streaming app in #2. Note that condenser microphones often require phantom power (the Mic Mate draws phantom power via the USB port of the computer). Ustream recognizes most audio devices.
4. A decent camera, preferably high def, that can interface with the device in #1 and is compatible with the live streaming app in #2. Some laptops and tablets have built in cameras that are high quality, but this requires optimal placement of the device to capture the performance.
Once you have the right equipment, TEST IT! You want to make sure you have all the equipment you need and that it works as intended. Also make sure the venue where you will be streaming from has Internet access for your use. Nothing is worse than experiencing technical difficulties in a live setting. Testing helps ensure there are none.
Get to the venue as early as possible to set up the gear and ensure it is working properly.
Set up the microphone(s) and camera in a location that optimally captures the performance but is out of the way of obstacles, spectators, and possible spilt beer. Use your best judgement. For example, if the audience will be between the stage and the camera, make sure the camera has line of sight to the stage once the room is full of bobbing heads. Place microphones for optimal capture of the sound. You may want them behind barriers so they are not accidentally knocked down. If there is a sound guy or booth, placing mikes there can sometimes ensure good sound, since presumably the sound guy is striving for the best sound at his or her location in the room.
Activate the live streaming app well in advance of the start of the performance. You can always edit out dead space at the beginning but you don't want your viewers to miss the show opener.
Check on the hardware and software as often as possible during the show. Optimally have a dedicated person manning (or womanning) the gear to keep it running smoothly and alert you to any problems. If there are breaks in the performance, you can stop and start the live stream in order to save the archives as separate files, for example, if there are two different acts performing. This also allows you to eliminate some dead air in the archived performance.
The Ustream free app allows you to save performances as archives for 60 days, ample time to edit the videos and upload to Youtube, where they are permanent.
The biggest danger in live streaming a public music concert is making sure the stream setup works and is not interrupted due to technical difficulties or someone spilling a drink on your computer or knocking over a mike stand.
Always test your live stream hardware and software before going live. Make sure the venue has wifi and is willing to give you access.
Optimally, having someone who is not performing direct the live stream capture and protect the gear is optimal. But in most settings, if you can place the camera, microphone, and hardware in a safe location and cordon it off in some way, you are probably fine. If there is a sound guy present, ask him or her to keep an eye on the gear. They may even be willing to run it for you if they know how.