Setting up the Bridge

Bridge is a small program that shares one folder of music, video, and karaoke files from your computer with a party. This page takes you from nothing to a song playing on the screen. It assumes you know how to download a file and choose a folder, and nothing more.

What goes where

Your files stay on your computer. Bridge tells Let’s DJ the names of your songs, and sends the small pictures that sit beside them, so that guests can search from their phones. It does not send the songs. When one is about to play, the screen fetches it straight from your computer, across your own network.

That last part is the one thing to plan around: the computer running Bridge and the screen must be on the same network, which in a home means the same wifi or the same router. Guests’ phones do not have to be. They can be on mobile data.

Before you start

• A Mac or a Windows PC that will be switched on and awake for the whole party. If it goes to sleep, the screen cannot reach your songs.
• A folder of files. The two worked examples show what to put in one: a karaoke night and sharing music and video.
• A screen: any device with a web browser that is on the same network as the computer. A laptop plugged into a television will do, and so will a streaming box or a smart television with a browser. You open Let’s DJ on it and start the party.
• A Let’s DJ account. It is free and you can make it in step 4. Guests never need one.

1. Download

Get Bridge from the download page. There is one file for Mac and one for Windows.

On a Mac: Open the file and drag Let’s DJ Bridge into Applications. The first time you open it, macOS asks you to confirm it came from the internet: choose Open.

On Windows, expect a warning, and know before you see it that it is expected. The first time you run the installer Windows will probably show a blue window that says “Windows protected your PC”. Nothing is wrong. The section below shows exactly what to click.

2. Open it

The first time, a window opens that says “Welcome to lets.dj Bridge”. After that Bridge lives in your menu bar (on a Mac, at the top of the screen) or your system tray (on Windows, at the bottom right, where it may be hidden behind a small arrow). Click its icon to bring the window back.

Bridge starts by itself when you log in, so that it is already running on the night. You can turn that off under Settings in its window, where it says “Start when I log in”. The window is in English for now, and this page quotes its words exactly so that you can match them.

3. Choose your folder

Press Choose folder… and pick the folder that holds your files. Bridge reads that folder and every folder inside it. It only ever reads: it does not change, move, or delete anything.

After that it keeps watching. Drop a file into the folder in the middle of a party and it appears on everyone’s phone a couple of seconds later. If your folder is on a network drive, a change can take up to five minutes to be noticed. To choose a different folder later, press Change… beside the folder’s name.

4. Connect to your account

Now the window says “Connect to your lets.dj account”. It shows a short code, like K7QM-X4NP, and a button.

1. Press “Open the page to connect”. Your browser opens a Let’s DJ page. If you would rather, you can open the same page on another device, such as your phone.
2. Sign in, or create an account. A new account asks for a code that is emailed to you, which can take a minute to arrive and sometimes lands in spam. Bridge waits for you. The window says how long the code works, which is at least half an hour, and if it runs out, a new one appears and you press the button again.
3. Check that the request is yours. The page says which computer is asking to connect, and shows the same code as the Bridge window. Carry on only if the codes match and you have just opened Bridge yourself. If somebody sent you this link, close the page.
4. Name the library (“Karaoke”, say) and press Connect.

The page says “Connected”, and the Bridge window changes to “Serving your songs”, with a count of how many it found and how many of them the screen cannot play. Songs show up in search on every phone within a few seconds.

5. Bring it to a party

In a party, open Settings, then Libraries, and add your library to the party. You choose there whether everyone at the party can search it, or only you. A library you share can be searched by every guest, and they can queue songs from it. A library you do not share is yours alone.

From the library’s own page, which you reach from My Libraries, you can correct a title, change an artist, or swap a picture for any song. That never touches your files.

The question Chrome asks, before it asks it

The first time the screen plays a song from your computer, Chrome will stop and ask you a question. So will browsers built on it, such as Edge. A box appears near the address bar with the name of the site, app.lets.dj, and Allow and Block buttons. The wording changes from one version of Chrome to the next, but it is always a short question that mentions your local network, such as “Look for and connect to any device on your local network”.

It is expected, and the answer is Allow. Chrome now asks this of every website that tries to reach something inside your home, in case a site is poking around your printer, your router, or your cameras. Here that is exactly the point. Your songs are on your computer, and your computer is on your home network. Allow lets the Let’s DJ page on that screen connect to devices on your network. Let’s DJ uses that to reach your computer, and for nothing else.

Chrome asks once for each screen and remembers the answer. It is not asked on phones, because phones do not fetch the songs. The screen does.

If the answer is Block, or nobody was there to press anything, nothing from your computer will play on that screen. The first song is skipped, in case it was only that one file; after that the screen stops and says so, names your library, and points at this permission as the likeliest cause. The remedy is in the troubleshooting section. It is still far easier to avoid than to undo in front of a room, which is why the next part matters.

Try it before the guests arrive. On the screen you will really use, start a party, add your library, queue any one song from your phone, and press Allow when Chrome asks. The first time a screen plays anything it may also want one tap on the screen itself before it makes sound; that is a rule of browsers and not of Let’s DJ. Do it now, with nobody watching, and the real night will not have a first time in it.

Two things about that rehearsal. The answer belongs to that screen’s browser, so allowing it on your laptop does nothing for a television. If the screen is a television or a streaming box, do the rehearsal on that device, with its own remote. And Safari on a Mac did not ask at all when we tried it. We have not been able to test every television browser, so if one you use asks a question like this one, Allow is what it needs.

If Windows says “Windows protected your PC”

This is a message Windows shows for any app it does not recognise yet. Bridge is not signed with a certificate Microsoft knows, so Windows cannot tell who made it. It does not mean the file is damaged, and you have not done anything wrong. Only run an installer you downloaded from this page.

1. Click “More info” in the window. It is a small link under the message.
2. A “Run anyway” button appears. Click it.
3. If Windows then asks whether to let the app make changes to your device, choose Yes. The installation carries on as normal.

You should only see this when you first run the installer. We plan to sign the app in a later release, and this step will go away.

When something does not work

The screen says nothing from your library will play on it, usually after skipping a song first. The screen is being refused, or cannot reach your computer. The usual causes, in the order to check them:

1. The permission was blocked. Click the small icon at the left of the address bar on the screen, find Local network access, switch it to Allow, and reload the page. On a television, use the browser’s own site settings.
2. The computer is asleep, or Bridge is not running. Wake it, and check that Bridge’s window says “Serving your songs”. Turn off sleep for the evening.
3. The screen and the computer are on different networks. A guest network and the main network are different networks, even from the same router.
4. Your router is refusing the name. Bridge’s address looks like 0123456789abcdef.letsdj.io, a public name that points at your computer inside your home. Some routers and some DNS filtering services block exactly that, as a protection called DNS rebinding protection. We cannot change it from our side. Many routers that have the setting let you exempt a domain, and letsdj.io is the one to exempt.

Once you have fixed whichever it was, press Start again on your phone and the screen tries the same song afresh.

The screen says the library is not reachable. Let’s DJ has no address for it. Open the Bridge window: if it is not running, start it, and if it says it needs to be reconnected, press Reconnect.

Songs are missing. Check the folder Bridge is serving (it is shown in its window), and wait a few seconds. Then check the file types: a file Bridge catalogues but the screen cannot play is counted in the window and left out of search, and some kinds are not catalogued at all. A karaoke night lists them.

The window says “Can’t read your folder”. If the folder is on an external drive or a network share, check that it is connected, and press Try again, or choose another folder.

The window says “Needs to be reconnected”. The library was removed from your account, or Bridge was disconnected. Press Reconnect and go through step 4 again.

The window says a port is in use. Another copy of Bridge may already be running, or another program has it. Choose another port in Settings.

I cannot find the window. Click Bridge’s icon in the menu bar or the system tray. Opening Bridge a second time also brings the first one forward.

Linux, a NAS, or something else

Bridge can also run from a terminal or in Docker, which suits Linux machines and NAS boxes. Everything we publish is on the releases page. The download page links to that page.