把ios录音转换为mp3格式

NSMutableDictionary * recordSetting = [NSMutableDictionary dictionary];

[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey];//

[recordSetting setValue:[NSNumber numberWithFloat:8000.0] forKey:AVSampleRateKey];//采样率
[recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];//声音通道，这里必须为双通道
 [recordSetting setValue:[NSNumber numberWithInt:AVAudioQualityLow] forKey:AVEncoderAudioQualityKey];//音频质量

在转换mp3端的代码为:

NSString *cafFilePath = cafFilePathName;    //caf文件路径

NSString *mp3FilePath = mp3FilePathName;//存储mp3文件的路径

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 header

            FILE *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_num_channels(lame,1);//设置1为单通道，默认为2双通道

            lame_set_in_samplerate(lame, 8000.0);//11025.0

            //lame_set_VBR(lame, vbr_default);

            lame_set_brate(lame,8);

            lame_set_mode(lame,3);

            lame_set_quality(lame,2); /* 2=high 5 = medium 7=low 音质*/

            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);
                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);
            return YES;
        }
        return NO;
    }
    @catch (NSException *exception) {
        NSLog(@"%@",[exception description]);
        return NO;
    }
    @finally {
        NSLog(@"执行完成");
    }