How to Extract Text from PPT, PPTX, and ODP Files Using Open XML SDK in .NET

Extracting Text from PPT, PPTX, ODP Using Open XML SDK

Open XML SDK

The Open XML SDK provides a highly structured and efficient method for extracting text from presentation files—especially PPTX, which adheres to the Open XML standard. By offering direct access to the underlying XML, this SDK enables faster and more flexible handling of slide content compared to traditional methods.

Direct XML Access

• Analyze Text Directly: The Open XML SDK lets you extract text from XML parts without rendering slides.
• Structured Elements: Because text is stored in well-defined XML tags, it’s simpler to retrieve and process.

Example: Extracting Text Directly from Slide XML Content

using (PresentationDocument presentation = PresentationDocument.Open("presentation.pptx", false))
{
    var slidePart = presentation.PresentationPart.SlideParts.FirstOrDefault();
    if (slidePart != null)
    {
        var textElements = slidePart.Slide.Descendants<DocumentFormat.OpenXml.Drawing.Text>();
        foreach (var text in textElements)
        {
            Console.WriteLine(text.Text);
        }
    }
}

Performance Advantages

• Faster Extraction: Bypasses the overhead of opening PowerPoint or other high-level APIs.
• Lower Memory Usage: Only relevant XML parts are accessed, reducing resource consumption.
• No Microsoft PowerPoint Needed: Frees you from extra installation requirements.

Example: Efficiently Extracting Text Without Loading the Entire Presentation

using (PresentationDocument presentation = PresentationDocument.Open("presentation.pptx", false))
{
    foreach (var slidePart in presentation.PresentationPart.SlideParts)
    {
        var texts = slidePart.Slide.Descendants<DocumentFormat.OpenXml.Drawing.Text>().Select(t => t.Text);
        Console.WriteLine(string.Join(" ", texts));
    }
}

Identifying Text Elements

Specifics of Extracting Text from Presentations

When extracting text from presentations, consider these factors:

• Text May Reside in Different Sections: Regular slides, master slides, layouts, or speaker notes.
• Default Placeholders: Master slides and layouts can include placeholders (e.g., “Click to edit Master title style”) that aren’t actual presentation content.
• Filtering Empty or Hidden Text: Some elements might be empty or not intended for display.

Tags Containing Text

In a PPTX file, text is generally stored in:

• <a:t> elements inside <a:p> (paragraphs)
• <a:r> elements (text segments within paragraphs)

Example: Extracting All Text Elements from a Slide

var textElements = slidePart.Slide.Descendants<DocumentFormat.OpenXml.Drawing.Text>();
foreach (var text in textElements)
{
    Console.WriteLine(text.Text);
}

ODP and PPT

Inability to Extract Text Directly

• Unlike PPTX, PPT (binary format) and ODP (OpenDocument Presentation) are not supported by Open XML SDK.
• PPT stores content in a closed binary format, complicating text extraction.
• ODP relies on OpenDocument XML, which differs structurally from PPTX.

Workaround: Converting to PPTX

To extract text from PPT or ODP, the recommended approach is:

1. Convert PPT → PPTX using PowerPoint or a third-party tool.
2. Convert ODP → PPTX via LibreOffice or PowerPoint.
3. Extract text from the new PPTX using Open XML SDK.

Example: Converting ODP to PPTX via LibreOffice Command Line

soffice --headless --convert-to pptx presentation.odp

Supported Platforms and Frameworks

• Windows: .NET Framework 4.6.1 and above, .NET Core 2.1+, .NET 5/6/7.
• Linux/macOS: .NET Core 2.1+, .NET 5/6/7.
• Cloud Environments: Microsoft Azure Functions, AWS Lambda (.NET Core), Docker containers.
• Compatibility with Office Applications: No Microsoft Office installation required.
• Supported Programming Languages: Open XML SDK can be used with C#, VB.NET, F#, and other .NET-supported languages.

Conclusion

Leveraging the Open XML SDK for PPTX text extraction offers both efficiency and clarity, whereas PPT and ODP demand an initial conversion step for smooth processing. Adopting this approach ensures high performance, flexibility, and broad compatibility with modern .NET applications.