iOS 录制音频文件，播放，转化成mp3上传

文章结束后实现：

• 用户点击 录音按钮 录制声音
• 松开 录音按钮 的时候，音频文件转换为 mp3 格式上传到服务器
• 点击 播发按钮 播放之前录制的声音文件

需要的类

1： 导入 AVFoundation 框架，使用：

• AVAudioRecorder， 声音录制
• AVAudioPlayer， 声音播放

2： 需要 lame 进行声音转化

plist 配置

允许使用麦克风

屏幕快照 2017-07-19 下午5.10.08.png

代码

示例代码：

import UIKit
import AVFoundation

class ViewController: UIViewController {
    
    private var session: AVAudioSession!

    private var recorder: AVAudioRecorder!
    private var player: AVAudioPlayer!
    
    private var pcmPath: String!
    private var mp3FilePath: String!
    
    private var recorderSetting: [String: AnyObject]!
    
    private var mp3FileURL: URL!
    
    private let avSampleRateKey = 44100
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        session = AVAudioSession.sharedInstance()
        try! session.setActive(true)
        
        let docDic = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
        
        pcmPath = docDic + "/play.pcm"
        mp3FilePath = docDic + "/play.mp3"
        
        mp3FileURL = URL(fileURLWithPath: mp3FilePath)
        
        recorderSetting =
            [
                AVFormatIDKey: NSNumber(value: kAudioFormatLinearPCM),
                AVNumberOfChannelsKey: 2 as AnyObject, //录音的声道数，立体声为双声道
                AVEncoderAudioQualityKey : AVAudioQuality.max.rawValue as AnyObject,
                AVEncoderBitRateKey : 640000 as AnyObject,
                AVSampleRateKey : avSampleRateKey as AnyObject //录音器每秒采集的录音样本数
        ]
    }
    
    
    @IBAction func touchDown() {
        do {
            try session.setCategory(AVAudioSessionCategoryPlayAndRecord)
            
            recorder = try AVAudioRecorder(url: URL(string: pcmPath)!, settings: recorderSetting)
            recorder.isMeteringEnabled = true
            recorder.record()
        } catch let error {
            print("create recorder error: \(error)")
        }
    }
    
    @IBAction func touchUp() {
        recorder.stop()
        
        DispatchQueue.global().async {
            let success = AudioTransform.transformToMp3(fromPath: self.pcmPath,
                                                        toMp3Path: self.mp3FilePath,
                                                        withAVSampleRateKey: Int32(self.avSampleRateKey))
            
            DispatchQueue.main.async {
                print("transform success")
                if success {
                    do {
                        let data = try Data(contentsOf: self.mp3FileURL!)
                        print("data: \(data)")
                        DemoModel.uploadRecord(data: data) { (success, info) in
                            
                        }
                    } catch let error {
                        print("upload audio error: \(error)")
                    }
                }
            }
        }
    }
    
    @IBAction func play() {
        do {
            try session.setCategory(AVAudioSessionCategoryPlayback)
            
            player = try AVAudioPlayer(contentsOf: recorder.url)
            player.play()
        } catch let error {
            print("paly audio error: \(error)")
        }
    }
}

注意需要为 录制按钮 实现:

• touchDown 事件（按住按钮触发）
• touchUpInside 事件（松开按钮触发）

转化为 mp3 代码：

#import "lame.h"

@implementation AudioTransform

+ (BOOL)transformToMp3FromPath:(NSString *)originalPath
                     toMp3Path:(NSString *)mp3Path
           withAVSampleRateKey:(int)rateKey {
    @try {
        int read, write;
        
        FILE *pcm = fopen([originalPath cStringUsingEncoding:1], "rb");  //source
        fseek(pcm, 4*1024, SEEK_CUR);                                    //skip file header
        FILE *mp3 = fopen([mp3Path cStringUsingEncoding:1], "wb");       //output
        
        const int PCM_SIZE = 8192;
        const int MP3_SIZE = 8192;
        short int pcm_buffer[PCM_SIZE*2];
        unsigned char mp3_buffer[MP3_SIZE];
        
        lame_t lame = lame_init();
        lame_set_in_samplerate(lame, rateKey);
        lame_set_VBR(lame, vbr_default);
        lame_init_params(lame);
        
        do {
            read = (int)fread(pcm_buffer, 2*sizeof(short int), PCM_SIZE, pcm);
            if (read == 0)
                write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);
            else
                write = lame_encode_buffer_interleaved(lame, pcm_buffer, read, mp3_buffer, MP3_SIZE);
            
            fwrite(mp3_buffer, write, 1, mp3);
            
        } while (read != 0);
        
        lame_close(lame);
        fclose(mp3);
        fclose(pcm);
    }
    @catch (NSException *exception) {
        NSLog(@"%@",[exception description]);
        return false;
    }
    @finally {
        return true;
    }

}


@end

注意：需要使用 lame 这个小插件实现转化，lame下载地址。你也可以直接使用Demo内的 fat-lame 里面是已经编译好的文件 (转化文件是用 Objective-C 写的，在 Swift 项目中需要一个bridge 文件)

屏幕快照 2017-07-19 下午5.33.17.png

录制完声音后，如果播放的时候发现 声音变小
在播放声音的方法内设置：

try! session.setCategory(AVAudioSessionCategoryPlayback)

录制声音的方法内设置：

try! session.setCategory(AVAudioSessionCategoryPlayAndRecord)

Demo 地址

参考链接：
音频的文件格式和数据格式