Set XMP Media Management Metadata

This guide will show how to set media management XMP metadata.

Before you begin

First of all you should get your API key from your UniCloud account.

If this is your first time using UniPDF SDK, follow this guide to set up a local development environment.

Project setup

Clone the project repository

In your terminal, clone examples repository. It contains the Go code we will be using for this guide.

git clone

Navigate to the metadata folder in the unipdf-examples directory.

cd unipdf-examples/metadata

Configure environment variables

Replace the UNIDOC_LICENSE_API_KEY with your API credentials from your UniCloud account.





How it works

The import section in line 3-13 imports unipdf packages and other necessary libraries. The init function which is defined in lines 15-22 authenticates your request.

The main function defined in lines 24-122 sets the media management metadata. In this function, lines 25-31 the input and the output file paths are processed from the command line argument. The time taken to process the document is measured in lines 34-38. A new pdf reader is instantiated using NewPdfReaderFromFile in lines 41-45.

A new pdfWriter is created from the reader object in lines 48-51 using ToWriter method of the the PdfReader. The section in lines 54-69 extracts metadata from the input file if it already exists, otherwise it creates a new xmputil.Document.

in lines 71-82 a new media management is created xmputil.MediaManagement. The media management options is set in lines 84-92. In lines 93-95 the media management object is set to the XMP document using xmpDoc.SetMediaManagement(mmOptions).

The XMP document is marshaled into XML byte stream in lines 101-104. Then a new PdfObjectStream is created from the byte stream using core.MakeStream(metadataBytes, nil). In lines 113-115 the stream metadata is set to the pdfWriter using SetCatalogMetadata(metadataStream).

Finally the document is written to file using pdfWriter.WriteToFile(outputPath) in lines 118-121.

Run the code

go run pdf_set_xmp_media_management_metadata.go <input.pdf> <output.pdf>

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