c# - 如何在 C# 中使用谷歌云 API 对大文件进行 OCR pdf 文件

Question

我有将 pdf 文件转换为文本的 c# 函数

当 pdf 文件为 5 页或更少时，它可以正常工作

但是当 pdf 文件有 6 页或更多页时出现此错误

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
   at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
   at System.Collections.Generic.List`1.get_Item(Int32 index)
   at Newtonsoft.Json.Linq.JContainer.GetItem(Int32 index)
   at CallSite.Target(Closure , CallSite , Object , Int32 )

这是我的代码

    private string OCRPDF(string pdfFile)
    {
        client = ImageAnnotatorClient.Create();
        //var client = ImageAnnotatorClient.Create();
        Byte[] bytes = File.ReadAllBytes(pdfFile);
        var content_byte = ByteString.CopyFrom(bytes);

        var syncRequest = new AnnotateFileRequest
        {
            InputConfig = new InputConfig
            {
                Content = content_byte,
                // Supported mime_types are: 'application/pdf' and 'image/tiff'
                MimeType = "application/pdf"
            }
        };

        syncRequest.Features.Add(new Feature
        {
            Type = Feature.Types.Type.DocumentTextDetection
        });

        List<AnnotateFileRequest> requests =
            new List<AnnotateFileRequest>();
        requests.Add(syncRequest);

        string response = client.BatchAnnotateFiles(requests).ToString();

        dynamic pdfJSON = JObject.Parse(response);

        int totalPages = Convert.ToInt32(pdfJSON.responses[0].totalPages);

        if (totalPages > 5)
        {
            totalPages = 5;
        }

        string pdfText = "";
        for (int i = 0; i < totalPages; i++)
        {

            pdfText = pdfText + " " + pdfJSON.responses[0].responses[i].fullTextAnnotation.text;
        }
        //pdfText.Replace("\n", "\r\n");

        return pdfText;
    }