使用lamp第三方庫

 - (void)toMP3
{
    @try
    {
        [ShowLoading show:NO];
        int read, write;
        FILE *pcm = fopen([[NSHomeDirectory() stringByAppendingPathComponent:_strCafSavePath] cStringUsingEncoding:1], "rb");  //source 被轉換的音頻文件位置
        fseek(pcm, 4*1024, SEEK_CUR);                                   //skip file header
        FILE *mp3 = fopen([[NSHomeDirectory() stringByAppendingPathComponent:_strMp3SavePath] cStringUsingEncoding:1], "wb");  //output 輸出生成的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, 44100);
        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
    {
        [ShowLoading hidden];
        if ([self.delegate respondsToSelector:@selector(saveVoiceFinish)]) {
            [self.delegate saveVoiceFinish];
        }
    }
}