iOS 使用lame库将wav转mp3

- (NSString *)audioPCMtoMP3:(NSString *)wavPath {
    NSString *cafFilePath = wavPath;
    NSString *mp3FilePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject stringByAppendingPathComponent:@"ddd.mp3"];
    NSFileManager* fileManager = [NSFileManager defaultManager];
    if([fileManager removeItemAtPath:mp3FilePath error:nil]){ NSLog(@"删除原MP3文件");
        
    }
    @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, 22050.0);
        lame_set_in_samplerate(lame, 4000.0);
        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 {
        return mp3FilePath;
        
    }
    
}

这里边的采样率可以更改的，也就是那个4000

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