How to extract metadata from PDF article using Endnote

Can anyone help me, how to extract metadata from PDF article. I have huge PDF article collection, I want to add to endnote and extract all metadata. Even I tried to import PDF file but it does not display properly and even full title is not coming in endnote, so please tell me how to do it, or if any body have such video, that will be more helpful.

My understanding of how EndNote imports PDFs is that it looks for a DOI on the first page of the PDF. Then it uses this to grab the metadata from the website for the full text (using the DOI to get to that website.) This means it will only correctly import PDFs that are native PDFs (the text is readable, not a scan of a print document - unless you run OCR text recognition on it in Adobe Acrobat) AND it must have a DOI on the first page. It does not grab metadata directly from the PDF.

That means that many older PDFs will not correctly import the article information.