carabina / live

Demonstrate how to build a live broadcast app.

This project is to demonstrate how to build a live broadcast app. It include these features:

• create a room to broadcast your live stream
• join a room to watch the live
• send likes and comments

Introduction

• RTMP server - Nginx RTMP module(https://github.com/arut/nginx-rtmp-module)
• WebSocket server - Socket.io(http://socket.io/)
• iOS client - VideoCore(https://github.com/jgh-/VideoCore) to push stream, IJKPlayer(https://github.com/Bilibili/ijkplayer) to play stream

How to run

I've set up a test server at 139.196.232.10, so you can directly run the iOS project.

1. Nginx RTMP server

You can set up your own rtmp server, the guidance can be found here: https://github.com/arut/nginx-rtmp-module

2. WebSocket server

Just go to the live-server folder, run npm install, then start the server by node app.js

3. iOS client

Go the the live-ios folder, run pod install(must use cocoapods 0.39.0)

In Config.swift, update the server url:

struct Config {
    static var rtmpPushUrl = "rtmp://139.196.232.10/live/"
    static var rtmpPlayUrl = "rtmp://139.196.232.10/live/"
    static var serverUrl = "http://139.196.232.10:3000"
}

The app can also be run on a simulator, but to broadcast, you need to run it on a real device

Tutorial

1. Live streaming

The basic live streaming flow is:

broadcaster -> rtmp -> media server -> cdn -> rtmp or hls -> audience

For the simplest case, we don't need a cdn server, then the flow will be:

broadcaster -> rtmp -> media server -> rtmp or hls -> audience

That is, the boadcaster push the live stream using the RTMP protocal to a media server, the audience pull the stream from the server using RTMP or HLS protocal.

Some explaination for RTMP and HLS

• RTMP: RTMP is used to stream audio, video or data and is originally a proprietary protocol introduced by Macromedia (owned by Adobe). The protocol is TCP-based and offers therefore persistent connections. In short, RTMP encapsulates MP3/AAC audio and MP4/FLV video multimedia streams.

• HLS: HTTP Live Streaming is known as HLS. As the name implies, it is the media streaming communications protocol based on HTTP; developed by Apple as part of their QuickTime, Safari, OS X, and iOS products. How does it work? It breaks the overall stream into a sequence of small HTTP-based files (.ts: Transport Stream). These transport stream files are indexed in the file .m3u8. It is required to download first the .m3u8 playlist to play a live stream.

For the media server, there are serveral choices:

• Adobe media server
• Red5
• Nginx RTMP module
• crtmpserver

After setting up the server, you can test it using ffmpeg(install it by brew install ffmpeg)

• push stream

ffmpeg -f avfoundation -framerate 30  -i "1:0" -f flv rtmp://server-url

• watch the stream: go to this site: https://www.hlsplayer.net/rtmp-player

p.s. Lots of live stream cloud already covers the media server and cdn parts. You just need to push/pull the stream from it.

2. iOS RTMP libs

There are serveral open source projects supporting RTMP, this project uses:

• VideoCore(https://github.com/jgh-/VideoCore) to push rtmp stream
• IJKPlayer(https://github.com/Bilibili/ijkplayer) to pull rtmp stream

You can find the usage of these libs in their project pages.

3. Websocket server

This project uses socket.io to handle the client-server communication, the logic is very simple, on the server side:

var rooms = []

io.on('connection', function(socket) {

  socket.on('create_room', function(roomKey) {
    rooms.push(roomKey)
    socket.roomKey = roomKey;
    socket.join(roomKey);
  });

  socket.on('close_room', function(roomKey) {
    closeRoom(roomKey)
  });

  socket.on('disconnect', function(roomKey) {
    if (socket.roomKey) {
      closeRoom(socket.roomKey)
    }
  });

  socket.on('join_room', function(roomKey) {
    socket.join(roomKey);
  });

  socket.on('upvote', function(roomKey) {
    io.to(roomKey).emit('upvote')
  });

  socket.on('comment', function(data) {
    io.to(data.roomKey).emit('comment', data)
  });
});

On the client side, it uses the socket.io swift client(https://github.com/socketio/socket.io-client-swift), the logic is also simple:

create, join, or close a room:

socket.on("connect") {data, ack in
    self.socket.emit("create_room", self.room.key)
}

socket.on("connect") {data, ack in
    self.socket.emit("join_room", self.room.key)
}

socket.emitWithAck("close_room", room.key)(timeoutAfter: 0) {data in
    self.socket.disconnect()
}

publish likes and comments events:

socket.emit("upvote", room.key)
socket.emit("comment", [
    "roomKey": room.key,
    "text": text
])

listen likes and comments events:

socket.on("upvote") {data ,ack in
    self.emitterView.emitImage(R.image.heart()!)
}
        
socket.on("comment") {data ,ack in
    let comment = Comment(dict: data[0] as! [String: AnyObject])
    self.comments.append(comment)
    self.tableView.reloadData()
}