需首先引用lamp.h,libmp3lame.a

- (void)audio_PCMtoMP3:(NSString *) cafFilePath ToMp3File:(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

        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

    {

     }

}