func: static int64_t find_tag(AVIOContext *pb, uint32_t tag1)
  
  {
  
      unsigned int tag;
  
      int64_t size;
  
  
  
      for (;;) {
  
          if (url_feof(pb))
  
              return AVERROR_EOF;
  
          size = next_tag(pb, &tag);
  
          if (tag == tag1)
  
              break;
  
          wav_seek_tag(pb, size, SEEK_CUR);
  
      }
  
      return size;
  
  }
  