iOS 通过(lame)将录制音频转换成Mp3_swift pcm 转 mp3

为了iPhone 与 Android 实现音频互通. Mp3格式的音频文件再好不过了.这里主要用到lame(Mp3音频编码器).   

首先使用 AVAudioRecorder 进行音频录制之前,进行如下参数设置:(一定要设置成pcm线性编码格式)

// 定义音频的编码参数, 决定录制音频文件的格式, 音质, 容量大小等, 建议采用AAC的编码方式
    let recordSettings = [AVSampleRateKey: NSNumber(value: Float(44100.0)), // 声音采样率
                          AVFormatIDKey: NSNumber(value: kAudioFormatLinearPCM), // 编码格式
                          AVNumberOfChannelsKey: NSNumber(value: 2), //采集音轨
                          AVEncoderAudioQualityKey: NSNumber(value: Int32(AVAudioQuality.medium.rawValue)), // 音频质量
                          AVLinearPCMBitDepthKey: NSNumber(value: 16),
                          AVLinearPCMIsFloatKey: NSNumber(value: false),
                          AVLinearPCMIsBigEndianKey: NSNumber(value: false)]

lame 静态库主要有两个核心文件:

1:lame库加入工程中

2:核心转换代码(这里的代码直接引用oc的)(该处直接引用大神代码)

- (void)audio_PCMtoMP3  
{  
    NSString *mp3FileName = [self.audioFileSavePath lastPathComponent];  
    mp3FileName = [mp3FileName stringByAppendingString:@".mp3"];  
    NSString *mp3FilePath = [self.audioTemporarySavePath stringByAppendingPathComponent:mp3FileName];  
      
    @try {  
        int read, write;  
          
        FILE *pcm = fopen([self.audioFileSavePath 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 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);  
            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 {  
        self.audioFileSavePath = mp3FilePath;  
        NSLog(@"MP3生成成功: %@",self.audioFileSavePath);  
    }  
} 

lame静态库(支持64架构) https://pan.baidu.com/s/1dFHtTk9 提取码: smiw

demo地址:https://github.com/songhaisheng/SGRecorder

简书博客地址

https://www.jianshu.com/u/3c7c13f3dc6b