How to get metadata info from Flac file using LibFlac

Question

I am decoding Flac files in to wave files . After decoding file , I am getting stream info by this code

void metadata_callback(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
{
    (void)decoder, (void)client_data;


    /* print some stats */
    if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
        /* save for later */
        total_samples = metadata->data.stream_info.total_samples;
        sample_rate = metadata->data.stream_info.sample_rate;
        channels = metadata->data.stream_info.channels;
        bps = metadata->data.stream_info.bits_per_sample;

        fprintf(stderr, "sample rate    : %u Hz\n", sample_rate);
        fprintf(stderr, "channels       : %u\n", channels);
        fprintf(stderr, "bits per sample: %u\n", bps);
#ifdef _MSC_VER
        fprintf(stderr, "total samples  : %I64u\n", total_samples);
#else
        fprintf(stderr, "total samples  : %llu\n", total_samples);
#endif

}

Now I want to fetch metadata such as album name, picture ,artist name.

For this I tried this code

FLAC__StreamMetadata *tags;
        FLAC__bool success = FLAC__metadata_get_tags(infilePath, &tags);

        if (success) {
            printf("Got stream information");
            printf("metadata %u",tags->data.vorbis_comment.num_comments);
        }else {
            printf("Failed to get stream information");
        }

But I am getting Zero i.e 0 on console. Please help .