Here is C# code that demonstrates how to convert a PDF document to conformance with PDF/A-1b specification and show the detailed result of conversion:
/// <summary>
/// Converts a PDF document to conformance with PDF/A-1b specification and
/// shows the detailed result of conversion.
/// </summary>
/// <param name="pdfFilename">The filename of source PDF document.</param>
/// <param name="outputPdfFilename">The filename of output PDF document.</param>
public static void ConvertDocumentToPdfA1bDetalied(
    string pdfFilename,
    string outputPdfFilename)
{
    // determine that file must converted to the PDF/A-1b and saved back to the source file
    bool sameFile = pdfFilename.ToUpperInvariant() == outputPdfFilename.ToUpperInvariant();

    // create the PDF/A-1b converter
    Vintasoft.Imaging.Pdf.Processing.PdfA.PdfA1bConverter converter = 
        new Vintasoft.Imaging.Pdf.Processing.PdfA.PdfA1bConverter();
    converter.LzwFixupCompression = Vintasoft.Imaging.Pdf.PdfCompression.Zip;
    // converter.OutputIntentDestIccProfile = ...

    using (Vintasoft.Imaging.Processing.ProcessingState processingState = 
        new Vintasoft.Imaging.Processing.ProcessingState())
    {
        // subscribe to the events for monitoring the progress
        processingState.Progress += new System.EventHandler<Vintasoft.Imaging.ProgressEventArgs>(
            convertProcessingState_Progress);

        // execute the conversion
        Vintasoft.Imaging.Processing.ConversionProfileResult result = 
            converter.Convert(pdfFilename, outputPdfFilename, processingState);
        System.Console.WriteLine("finished.");

        // if PDF document is converted successfully
        if (result.IsSuccessful)
        {
            System.Console.WriteLine("Document converted to PDF/A-1b.");
        }
        // if PDF document is NOT converted
        else
        {
            if (!sameFile)
                System.IO.File.Delete(outputPdfFilename);

            System.Console.WriteLine("Cannot convert document to PDF/A-1b, unsolved problems:");
            // for each activated trigger
            foreach (Vintasoft.Imaging.Processing.IProcessingCommandInfo 
                command in result.ActivatedTriggers.Keys)
            {
                // output information about activated trigger
                System.Console.WriteLine(string.Format("  {0} ({1} matches)",
                    command,
                    result.ActivatedTriggers[command].Count));
            }
        }
    }
}

/// <summary>
/// Handles the Progress event of the ProcessingState.
/// </summary>
static void convertProcessingState_Progress(object sender, Vintasoft.Imaging.ProgressEventArgs e)
{
    System.Console.CursorLeft = 0;
    System.Console.Write(string.Format("Conversion {0}%...", e.Progress));
}