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Friday 2 September 2016

如何创建一个直播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, gifts, and comments
image  image

Introduction

How to run

I've set up a test server at 139.196.179.230, 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: 

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 to 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://139.196.179.230/mytv/"
    static var rtmpPlayUrl = "rtmp://139.196.179.230/mytv/"
    static var serverUrl = "http://139.196.179.230:3000"
}
The app can also 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
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:
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(room) {
    var roomKey = room.key
    rooms[roomKey] = room
    socket.roomKey = roomKey
    socket.join(roomKey)
  })

  socket.on('close_room', function(roomKey) {
    delete rooms[roomKey]
  })

  socket.on('disconnect', function() {
    if (socket.roomKey) {
      delete rooms[socket.roomKey]
    }
  })

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

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

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

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

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()
}
from https://github.com/ltebean/Live
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