pcm录音文件转转MP3方法

- ( void )audio_PCMtoMP3
{
    NSString *mp3FilePath = [[ NSSearchPathForDirectoriesInDomains ( NSCachesDirectory , NSUserDomainMask , YES ) lastObject ] stringByAppendingPathComponent : @"lv.mp3" ];
   
    @try {
        int read, write;
       
        FILE *pcm = fopen ([ self . pcmFilePath 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 ; //8192
        const int MP3_SIZE = 8192 ; //8192
        short int pcm_buffer[PCM_SIZE* 2 ];
        unsigned char mp3_buffer[MP3_SIZE];
       
        lame_t lame = lame_init ();
        lame_set_in_samplerate (lame, 7500.0 ); // 采样播音速度，值越大播报速度越快，反之。
        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 {
        //do some
    }
   

}