Archive PDF Tools V1.5.5: Bug Encountered During Compression

by Henrik Larsen 61 views

Hey everyone,

I've encountered a new bug in the latest version (1.5.5) of archive-pdf-tools, and I wanted to share it with you all and see if anyone else is experiencing the same issue or has any insights. I was trying to compress a PDF file when this error popped up. Let's dive into the details so we can figure this out together!

The Issue

So, I recently installed archive-pdf-tools version 1.5.5, excited to try out the new features and improvements. However, when I attempted to compress a PDF, I ran into a snag. Here’s a screenshot of the error I received:

[Image of the error]

As you can see in the image, there’s some kind of error occurring during the compression process. The specifics of the error message might be a bit cryptic at first glance, but we'll break it down.

Command Used

To give you more context, I’m including the exact command I used to trigger this bug. This should help in replicating the issue and pinpointing the cause. Here’s the command:

recode_pdf -J openjpeg --threads 8 --bg-downsample 3 --dpi 300 --mask-compression jbig2 --from-imagestack "extracted/page-001.jpg" --hocr-file "extracted/page-001.hocr" -o "extracted/test_page_001.pdf"

Let's break down what each part of this command does:

  • recode_pdf: This is the main command for the archive-pdf-tools, which is used to re-encode and compress PDF files.
  • -J openjpeg: This option specifies that we want to use the OpenJPEG codec for JPEG 2000 compression. OpenJPEG is known for its efficiency in compressing images while maintaining good quality.
  • --threads 8: This tells the tool to use 8 threads for processing. Using multiple threads can significantly speed up the compression process, especially for large files.
  • --bg-downsample 3: This option controls the downsampling of the background images. A value of 3 means the background images will be downsampled by a factor of 3, reducing their resolution and file size.
  • --dpi 300: This sets the target DPI (dots per inch) for the output PDF. A DPI of 300 is generally considered good for print quality.
  • --mask-compression jbig2: This specifies that we want to use JBIG2 compression for the mask layer. JBIG2 is a highly efficient compression method for bilevel (black and white) images, making it ideal for text and line art.
  • --from-imagestack "extracted/page-001.jpg": This indicates the input image file that will be used to create the PDF page. In this case, it's a JPEG image.
  • --hocr-file "extracted/page-001.hocr": This specifies the path to the hOCR file, which contains the OCR (Optical Character Recognition) data for the page. This data is used to make the PDF searchable and selectable.
  • -o "extracted/test_page_001.pdf": This sets the output file name for the compressed PDF.

By understanding the command, we can better analyze where the issue might be stemming from. It could be related to the OpenJPEG codec, the threading, downsampling, DPI settings, JBIG2 compression, or how the tool handles image and hOCR files.

Potential Causes and Troubleshooting

Now, let's brainstorm some potential causes for this bug and some steps we can take to troubleshoot it. It's always a process of elimination, so let's put on our detective hats!

1. OpenJPEG Codec Issues

Since the command uses the -J openjpeg option, there might be an issue with the OpenJPEG library or its integration with archive-pdf-tools. Here are a few things we can try:

  • Update OpenJPEG: Ensure that you have the latest version of the OpenJPEG library installed on your system. Sometimes, bugs are fixed in newer releases.
  • Try a Different Codec: As a test, try using a different JPEG codec, such as the standard JPEG encoder (if available), to see if the issue persists. This will help us determine if the problem is specific to OpenJPEG.
  • Check Compatibility: Verify that the version of OpenJPEG is compatible with archive-pdf-tools 1.5.5. There might be known compatibility issues between certain versions.

2. Threading Issues

The --threads 8 option tells the tool to use 8 threads, which can speed up processing but also introduce potential issues if not handled correctly. Here’s what we can investigate:

  • Reduce the Number of Threads: Try reducing the number of threads (e.g., --threads 4 or even --threads 1) to see if the error goes away. If it does, it might indicate a threading-related bug.
  • System Resources: Make sure your system has enough resources (CPU cores, memory) to handle the specified number of threads. Running too many threads on a resource-constrained system can lead to instability.

3. Image and hOCR File Issues

The bug might be related to the input image (extracted/page-001.jpg) or the hOCR file (extracted/page-001.hocr). Let's consider these possibilities:

  • Corrupted Image: The image file might be corrupted or in an unsupported format. Try opening the image in an image viewer to ensure it's valid. You could also try converting it to a different format (e.g., PNG) and see if that resolves the issue.
  • hOCR File Errors: The hOCR file might contain errors or be incompatible with the image. Try running the command without the --hocr-file option to see if the problem goes away. If it does, you might need to inspect the hOCR file for issues.
  • File Paths: Double-check that the file paths specified in the command are correct and that the files exist at those locations. A simple typo can cause the tool to fail.

4. Memory Issues

Compression, especially with high DPI and multiple threads, can be memory-intensive. If your system runs out of memory, it can lead to errors. Here’s how to check for memory issues:

  • Monitor Memory Usage: Use system monitoring tools (like Task Manager on Windows or top on Linux) to observe memory usage while running the command. If memory usage is consistently high (close to 100%), it could be a memory issue.
  • Reduce DPI or Downsampling: Try reducing the DPI (--dpi 150) or increasing the background downsampling (--bg-downsample 4) to reduce memory consumption.

5. Version-Specific Bug

It’s possible that this is a bug specific to version 1.5.5 of archive-pdf-tools. To verify this, you can try:

  • Downgrade Version: If possible, downgrade to a previous version of archive-pdf-tools (e.g., 1.5.4) and see if the issue persists. If the bug is gone in the older version, it’s likely a new bug in 1.5.5.

Next Steps and Community Input

So, what should we do next? Here’s my plan, and I'd love to hear your thoughts and suggestions:

  1. Replicate the Issue: If you're using archive-pdf-tools, try running the same command on your system to see if you can reproduce the bug. This will help confirm that it’s not just an isolated incident.
  2. Try Troubleshooting Steps: Go through the troubleshooting steps I mentioned above, such as checking OpenJPEG, reducing threads, and verifying file integrity.
  3. Share Your Findings: If you encounter the bug or have any insights, please share them in the comments below. The more information we gather, the better we can understand and resolve the issue.
  4. Report the Bug: If we confirm that this is a genuine bug, we should report it to the developers of archive-pdf-tools. They can then investigate the issue and release a fix in a future version.

Reporting a bug effectively involves providing as much detail as possible. Here’s what a good bug report should include:

  • Version Information: Specify the version of archive-pdf-tools you're using (1.5.5 in this case).
  • Operating System: Mention your operating system (e.g., Windows 10, macOS 11, Ubuntu 20.04).
  • Command Used: Include the exact command that triggers the bug.
  • Error Message: Provide the full error message, including any relevant stack traces or logs.
  • Steps to Reproduce: Clearly describe the steps needed to reproduce the bug.
  • Sample Files: If possible, provide sample files (e.g., the input image and hOCR file) that trigger the bug. Be mindful of privacy and avoid sharing sensitive information.
  • Troubleshooting Steps Taken: List any troubleshooting steps you’ve already tried, and their results.

By providing this information, you make it much easier for the developers to understand and fix the bug. Bug reports are a crucial part of the software development process, and your contributions can help improve the tool for everyone.

Let's Collaborate!

I believe that by working together, we can identify and resolve this bug. Your input, experiences, and suggestions are invaluable. So, please don’t hesitate to share your thoughts in the comments section below.

Let’s get this sorted out, guys! Thanks for your help, and let’s make archive-pdf-tools even better!

Update and Further Testing

I'm planning to continue testing different scenarios and configurations to gather more information about this bug. Here are a few things I’ll be focusing on:

1. Different Input Files

I’ll try using different input images and hOCR files to see if the bug is specific to certain types of files. This includes images with varying resolutions, color depths, and formats, as well as hOCR files generated by different OCR engines.

2. Different Command Options

I’ll experiment with different command options to see if any particular combination of options triggers the bug. This might involve changing the compression settings, DPI, downsampling, or other parameters.

3. Testing on Different Systems

If possible, I’ll try running the command on different operating systems and hardware configurations to see if the bug is system-specific. This can help identify compatibility issues or dependencies.

4. Debugging Tools

I might also explore using debugging tools to get more detailed information about what’s happening internally when the bug occurs. This could involve using debuggers or profilers to trace the execution of the code and identify the source of the error.

By conducting these tests, I hope to gather enough information to provide a comprehensive bug report to the developers. The more information we have, the easier it will be for them to diagnose and fix the issue.

Community Contributions and Discussions

I also want to encourage everyone in the community to contribute to this discussion. If you have any insights, suggestions, or experiences to share, please feel free to post them in the comments section. Here are some specific questions I’d love to hear your thoughts on:

  • Have you encountered this bug in version 1.5.5, or in any previous versions of archive-pdf-tools?
  • Do you have any experience with OpenJPEG or JBIG2 compression that might be relevant to this issue?
  • Have you tried any other troubleshooting steps that might help identify the cause of the bug?
  • Do you have any suggestions for how to improve the bug reporting process or the tool itself?

By sharing your knowledge and experiences, you can help make archive-pdf-tools a better tool for everyone. Community contributions are a vital part of the open-source development process, and I appreciate your participation.

Final Thoughts

Dealing with bugs can be frustrating, but it’s also an opportunity to learn and improve. By working together and sharing our experiences, we can help make archive-pdf-tools a more reliable and efficient tool for everyone. I’m committed to helping resolve this issue, and I appreciate your support and contributions.

So, let’s keep the discussion going, and let’s get this bug squashed! Thanks again for your help, guys!