iOS实现录音转码MP3及转码BASE64上传示例

ios 录音转码mp3及转码base64上传

一，开始录音

nslog(@"开始录音");

[self startrecord];

- (void)startrecord
{
  //删除上次生成的文件，保留最新文件
  nsfilemanager *filemanager = [nsfilemanager defaultmanager];
  if ([nstemporarydirectory() stringbyappendingstring:@"myselfrecord.mp3"]) {
    [filemanager removeitematpath:[nstemporarydirectory() stringbyappendingstring:@"myselfrecord.mp3"] error:nil];
  }
  if ([nstemporarydirectory() stringbyappendingstring:@"selfrecord.wav"]) {
    [filemanager removeitematpath:[nstemporarydirectory() stringbyappendingstring:@"selfrecord.wav"] error:nil];
  }
  
  //开始录音
  //录音设置
  nsmutabledictionary *recordsetting = [[nsmutabledictionary alloc] init];
  //设置录音格式 avformatidkey==kaudioformatlinearpcm
  [recordsetting setvalue:[nsnumber numberwithint:kaudioformatlinearpcm] forkey:avformatidkey];
  //设置录音采样率(hz) 如：avsampleratekey==8000/44100/96000（影响音频的质量）, 采样率必须要设为11025才能使转化成mp3格式后不会失真
  [recordsetting setvalue:[nsnumber numberwithfloat:11025.0] forkey:avsampleratekey];
  //录音通道数 1 或 2 ，要转换成mp3格式必须为双通道
  [recordsetting setvalue:[nsnumber numberwithint:2] forkey:avnumberofchannelskey];
  //线性采样位数 8、16、24、32
  [recordsetting setvalue:[nsnumber numberwithint:16] forkey:avlinearpcmbitdepthkey];
  //录音的质量
  [recordsetting setvalue:[nsnumber numberwithint:avaudioqualityhigh] forkey:avencoderaudioqualitykey];
  
  //存储录音文件
  recordurl = [nsurl urlwithstring:[nstemporarydirectory() stringbyappendingstring:@"selfrecord.wav"]];
  
  //初始化
  audiorecorder = [[avaudiorecorder alloc] initwithurl:recordurl settings:recordsetting error:nil];
  //开启音量检测
  audiorecorder.meteringenabled = yes;
  audiosession = [avaudiosession sharedinstance];//得到avaudiosession单例对象

  if (![audiorecorder isrecording]) {
    [audiosession setcategory:avaudiosessioncategoryplayandrecord error:nil];//设置类别,表示该应用同时支持播放和录音
    [audiosession setactive:yes error:nil];//启动音频会话管理,此时会阻断后台音乐的播放.
    
    [audiorecorder preparetorecord];
    [audiorecorder peakpowerforchannel:0.0];
    [audiorecorder record];
  }
}

二，停止录音

[self endrecord];


 - (void)endrecord
 {
   [audiorecorder stop];             //录音停止
   [audiosession setactive:no error:nil];     //一定要在录音停止以后再关闭音频会话管理（否则会报错），此时会延续后台音乐播放
 }

三，转码成mp3

- (void)transformcaftomp3 {
  mp3filepath = [nsurl urlwithstring:[nstemporarydirectory() stringbyappendingstring:@"myselfrecord.mp3"]];
  
  @try {
    int read, write;
    
    file *pcm = fopen([[recordurl absolutestring] cstringusingencoding:1], "rb");  //source 被转换的音频文件位置
    fseek(pcm, 4*1024, seek_cur);                          //skip file header
    file *mp3 = fopen([[mp3filepath absolutestring] cstringusingencoding:1], "wb"); //output 输出生成的mp3文件位置
    
    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, 11025.0);
    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]);
  }
  @finally {
    nslog(@"mp3生成成功");
    base64str = [self mp3tobase64];
  }
}

四，上传需要转码base64

 - (nsstring *)mp3tobase64{
   nsdata *mp3data = [nsdata datawithcontentsoffile:[nstemporarydirectory() stringbyappendingstring:@"myselfrecord.mp3"]];
   nsstring *_encodedimagestr = [mp3data base64encoding];
   nslog(@"===encoded image:\n%@", _encodedimagestr);
   return _encodedimagestr;
 }

备注：其中可以直接生成的.caf  .wav    有压缩的mp3需要转格式，不能直接录音生成

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