lets.dj

Worked example: a karaoke night

This is a worked example. You have a few hundred karaoke videos on a computer, you want a room to sing from them on Saturday, and you want to know exactly what to put where. It follows one folder from a pile of files to a queue on a television. Setting up the Bridge covers installing and connecting; this page is about what is in the folder.

The folder

Suppose the folder is called Karaoke, and looks like this:

Karaoke/
  ABBA - Dancing Queen.mp4
  ABBA - Dancing Queen.jpg
  Adele - Someone Like You.mp4
  Adele - Someone Like You.png
  Journey - Don't Stop Believin'.mp4
  Trịnh Công Sơn - Diễm Xưa.mp4
  Trịnh Công Sơn - Diễm Xưa.jpg
  Duets/
    Dolly Parton & Kenny Rogers - Islands in the Stream.mp4
  Birthday Song.mp4

Folders are fine, to any depth, and their names are ignored: Duets/ does nothing but keep you tidy. Anything whose name begins with a dot is skipped.

Naming files

Bridge works out a song’s artist and title from the file name, and only from the file name. It does not read the tags inside the file.

  • Artist - Title.mp4 is the pattern. A space, a hyphen, and a space separate the two. ABBA - Dancing Queen.mp4 is the song “Dancing Queen” by ABBA.
  • Underscores become spaces, so ABBA_-_Dancing_Queen.mp4 means the same thing.
  • The first separator wins. Dolly Parton & Kenny Rogers - Islands in the Stream.mp4 has the artist before the hyphen. If a title contains - itself, everything after the first one is the title.
  • A hyphen without spaces around it is not a separator. Don't Stop-Believin.mp4 has no artist.
  • No separator, no artist. Birthday Song.mp4 is a song called “Birthday Song” with nobody credited. It still works. It is simply searched by its title.
  • The extension is ignored, and may be in capitals: .MP4 is the same as .mp4.

Guests search by title or by artist, and accents are optional when they type, so “diem xua” finds “Diễm Xưa”.

If a name is wrong, do not rename the file. Open the library in the Let’s DJ app and correct the title or the artist there. That is kept apart from the file, it survives a rescan, and it follows the file even if you later rename or move it, because Bridge recognises a file by what is inside it and not by where it is.

Artwork

A picture beside each song makes the lists on everyone’s phone easier to read: it shows in search, in browse, in the queue, and on the now-playing bar. To give a song one, put an image next to the video with exactly the same name:

ABBA - Dancing Queen.mp4
ABBA - Dancing Queen.jpg
  • .jpg, .jpeg, .png, or .webp. Capital letters do not matter, so a phone’s IMG_0042.JPG beside IMG_0042.mp4 is found.
  • One picture for a whole folder works too. If a song has none of its own, Bridge uses a file in the same folder called folder.jpg or cover.jpg. This suits a disc ripped as one set.
  • Keep each picture under 1 MB. A larger one is skipped and the song carries on without it. A 1280×720 JPEG is typically around 70 KB, which is more than enough. Shrink anything that came from a scanner.
  • Pictures embedded inside a video or an audio file are not used. Bridge only looks at separate image files beside it.

What the television will play

The screen is a web browser, so it can play what a browser can play. MP4 files with H.264 video and AAC audio are what you want. WebM, M4V, and MOV usually work too.

Four kinds of video are very common in karaoke collections and will not play:

  • MKV
  • AVI
  • WMV
  • FLV

Bridge does not hide these from you. It lists them, counts them in its window (“812 (22 the TV can’t play)”), and shows them on the library’s page marked as ones that will not play. It keeps them out of search and browse, so that nobody queues a song and watches it fail in front of the room.

CDG and MP3 pairs are different, and need the most care. A karaoke disc is usually a .cdg file for the words and an .mp3 of the same name for the music, and it is the real format of most commercial karaoke. The screen cannot show a .cdg file at all, and Bridge does not read them. But the .mp3 half is an ordinary song to Bridge, so a folder of CDG pairs appears as a folder of songs with no words on the screen, which is a worse surprise than an empty one. Convert each pair into a single MP4 before you add it.

A file can have the right ending and still refuse to play. An MP4 is a box, and what is inside matters too. Video in H.265 (also called HEVC) plays on some screens and not on others, and so do some older or unusual audio formats. Bridge only looks at the file’s ending, so it will call such a file playable and the screen may then refuse it. If a particular song skips by itself, this is the likeliest reason.

To fix any of these, convert the file to MP4 with H.264 video and AAC audio, using a video converter such as HandBrake, which is free. Then move the original out of the folder, or it will stay on the list as a song that will not play.

Running the night

  1. Before anyone arrives, do the rehearsal in Setting up the Bridge: start the party on the screen, add the library, queue one song, and answer the browser’s question about the local network.
  2. Start the party on the television. It shows a join code and a QR code.
  3. Add the library to the party and leave it shared, so that everybody can search it. If you turn sharing off, only you can queue from it.
  4. Guests scan the code, search on their phones, and queue. They do not need accounts. The songs play in the order they were queued.

Keep the computer awake and Bridge running until the last song. If a song is added to the folder halfway through the night, it appears in search a few seconds later.