Golang implements voice chat

With the rapid development of Internet technology, more and more people are beginning to use voice chat to communicate online, and this method is becoming more and more popular among users. This article will introduce how to use Golang to implement voice chat function.

Golang is a programming language based on concurrent programming, suitable for network programming and high concurrency scenarios, so we can use Golang to implement the voice chat function. The realization of voice chat requirements requires the use of network communication technology and audio processing technology.

1. Basic principles of voice communication

The basic principle used in voice communication is the transmission of audio code streams. Usually we compress the audio stream into small packets and then transmit it through the network. This process requires the use of encoding and decoding technology. Encoding is the process of converting sound into digital signals, and decoding is the process of restoring digital signals to sound.

In network transmission, we need to use UDP protocol to transmit data. The UDP protocol is characterized by fast transmission speed but unreliability. Since voice calls have high real-time requirements, using UDP protocol transmission can improve the quality of voice calls.

2. Steps to implement voice chat function

1. Collect audio

Collecting audio requires a microphone to record sound. Golang provides some audio collection libraries. Such as PortAudio library, OpenAL library, etc. Here we take PortAudio as an example to collect audio.

First we need to install the PortAudio library:

brew install portaudio

Then install the go-portaudio library:

go get github.com/gordonklaus/portaudio

The code for collecting audio is as follows:

import (
    "github.com/gordonklaus/portaudio"
)

// 录音
func RecordAudio(ch chan []int16) {
    // 初始化PortAudio
    portaudio.Initialize()
    defer portaudio.Terminate()

    // 打开默认输入设备
    stream, err := portaudio.OpenDefaultStream(1, 0, 44100, len(window))
    if err != nil {
        log.Fatal(err)
    }
    defer stream.Close()

    // 开始录音
    err = stream.Start()
    if err != nil {
        log.Fatal(err)
    }
    defer stream.Stop()

    // 采集音频数据
    for {
        buffer := make([]int16, len(window))
        err := stream.Read(buffer)
        if err != nil {
            fmt.Println(err)
        }
        ch <- buffer
    }
}

2. Edit Decoding

After audio collection, it needs to be encoded and decoded before it can be transmitted. Encoding is to compress the collected audio data into small packets. There are many encoding algorithms, and commonly used ones include MP3, AAC, Opus, etc. Decoding is to restore compressed audio data to audio data.

Here we use the Opus encoding and decoding algorithm. Golang provides support for Opus, and you can use the opus library for encoding and decoding. Install the opus library:

brew install opus

Then install the go-opus library:

go get github.com/hraban/go-opus

The encoding and decoding code is as follows:

import (
    "github.com/hraban/go-opus"
)

// 初始化Opus编解码器
func InitOpus() (*opus.Encoder, *opus.Decoder) {
    // 初始化编码器
    enc, err := opus.NewEncoder(44100, 1, opus.AppVoIP)
    if err != nil {
        log.Fatal(err)
    }

    // 初始化解码器
    dec, err := opus.NewDecoder(44100, 1)
    if err != nil {
        log.Fatal(err)
    }

    return enc, dec
}

// Opus编码
func OpusEncode(enc *opus.Encoder, buffer []int16) []byte {
    data := make([]byte, 2048)
    n, err := enc.Encode(buffer, data)
    if err != nil {
        log.Fatal(err)
    }

    return data[:n]
}

// Opus解码
func OpusDecode(dec *opus.Decoder, data []byte) []int16 {
    buffer := make([]int16, 2048)
    n, err := dec.Decode(data, buffer)
    if err != nil {
        log.Fatal(err)
    }

    return buffer[:n]
}

3. Transmit audio data

Audio After data encoding and decoding is completed, network transmission is required. Here we choose the UDP protocol to transmit audio data. The code for transmitting data is as follows:

import (
    "net"
)

// 网络传输
func UDPTransfer(conn *net.UDPConn, addr *net.UDPAddr, ch chan []int16, enc *opus.Encoder) {
    for {
        buffer := <- ch
        data := OpusEncode(enc, buffer)
        _, err := conn.WriteToUDP(data, addr)
        if err != nil {
            fmt.Println(err)
        }
    }
}

4. Play audio

After receiving the audio data transmitted from the other party, we need to decode the audio data and then play it. Playing audio requires a player for processing. The audioplayer library in Golang can implement audio playback. Install the audioplayer library:

go get github.com/hajimehoshi/oto

The audio playback code is as follows:

import (
    "github.com/hajimehoshi/oto"
)

// 播放音频
func PlayAudio(player *oto.Player, ch chan []byte, dec *opus.Decoder) {
    for {
        data := <- ch
        buffer := OpusDecode(dec, data)
        player.Write(buffer)
    }
}

5. Audio chat end-to-end connection

Audio chat requires end-to-end connection, using UDP protocol Unable to establish stable connection. Therefore, we need to use STUN and TURN for NAT penetration to achieve end-to-end connection. Both STUN and TURN are technical services mainly used to solve P2P connection and NAT penetration problems.

6. Use WebRTC to implement voice chat

WebRTC is a voice and video chat technology based on web browsers, which can realize voice and video chat functions between browsers. WebRTC was jointly developed by Google and Mozilla and can operate network connections through the WebRTC API.

Using WebRTC to implement voice chat requires the use of an open source WebRTC framework, such as PeerJS, EasyRTC, etc.

3. Summary

This article uses Golang and Opus encoding and decoding algorithms to implement the voice chat function. The implementation process can be divided into audio collection, audio encoding and decoding, network transmission, audio playback and WebRTC connection. Wait a few steps. Use the audio collection library for audio collection, the Opus library for audio encoding and decoding, the UDP protocol for audio transmission, the audioplayer library for audio playback, and WebRTC for P2P connections. The code in this article shows how to use Golang language to implement voice chat, which can help beginners understand the knowledge of voice coding and network transmission.

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