- (void)initialRecord{//录音权限设置，IOS7必须设置，得到AVAudioSession单例对象AVAudioSession *audioSession = [AVAudioSession sharedInstance];//设置类别,此处只支持支持录音[audioSession setCategory:AVAudioSessionCategoryRecord error:nil];//启动音频会话管理,此时会阻断后台音乐的播放[audioSession setActive:YES error:nil];//录音参数设置设置NSMutableDictionary *recordSetting = [[NSMutableDictionary alloc]init];//设置录音格式  AVFormatIDKey==kAudioFormatLinearPCM//    [recordSetting setValue:[NSNumber numberWithInt:kAudioFormatMPEG4AAC] forKey:AVFormatIDKey];//caf的录制格式[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）//acc的采样频率//    [recordSetting setValue:[NSNumber numberWithFloat:44100] forKey:AVSampleRateKey];[recordSetting setValue:[NSNumber numberWithFloat:11025.0] forKey:AVSampleRateKey];//录音通道数  1 或 2 在录制caf文件时，需要使用双通道，否则在转换为MP3格式时，声音不对[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];[recordSetting setValue:[NSNumber numberWithInt:AVAudioQualityMin] forKey:AVEncoderAudioQualityKey];//录音文件保存的URLCFUUIDRef cfuuid = CFUUIDCreate(kCFAllocatorDefault);NSString *cfuuidString = (NSString*)CFBridgingRelease(CFUUIDCreateString(kCFAllocatorDefault, cfuuid));NSString * filename = [NSString stringWithFormat:@"%@.caf",cfuuidString];NSString *audioRecordFilePath = AUDIORECORDFILEPATH(filename);lastaudioRecordFilePath = audioRecordFilePath;//判断目录是否存在不存在则创建NSString *audioRecordDirectories = [audioRecordFilePath stringByDeletingLastPathComponent];NSFileManager *fileManager=[NSFileManager defaultManager];if (![fileManager fileExistsAtPath:audioRecordDirectories]) {[fileManager createDirectoryAtPath:audioRecordDirectories withIntermediateDirectories:YES attributes:nil error:nil];}NSURL *url = [NSURL fileURLWithPath:audioRecordFilePath];NSError *error=nil;//初始化AVAudioRecorder_recorder = [[AVAudioRecorder alloc]initWithURL:url settings:recordSetting error:&error];if (error != nil) {//NSLog(@"初始化录音Error: %@",error);}else{if ([_recorder prepareToRecord]) {//录音最长时间[_recorder recordForDuration:self.recorderDuration-1];_recorder.delegate=self;[_recorder record];//开启音量检测_recorder.meteringEnabled = YES;//开启定时器，音量监测_timer=[NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(volumeMeters:) userInfo:nil repeats:YES];}}}

//转编码为 mp3
- (void)audio_PCMtoMP3:(NSString *)cafFilePath andMP3FilePath:(NSString *)mp3FilePath
{NSFileManager* fileManager=[NSFileManager defaultManager];if([fileManager removeItemAtPath:mp3FilePath error:nil]) {NSLog(@"删除");}@try {int read, write;FILE *pcm = fopen([cafFilePath cStringUsingEncoding:1], "rb");  //source 被转换的音频文件位置if(pcm == NULL) {NSLog(@"file not found");} else {fseek(pcm, 4*1024, SEEK_CUR);                                   //skip file headerFILE *mp3 = fopen([mp3FilePath 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 = fread(pcm_buffer, 2 * sizeof(short int), PCM_SIZE, pcm);if (read == 0)write = lame_encode_flush(lame, mp3_buffer, MP3_SIZE);elsewrite = 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");}
}