Resuming JT Work

It’s now been two-and-a-half years since I last posted in this blog. During that time I pretty much completely ignored JT. However, I’m itching to take another stab at it. In addition, I’ve gotten a couple of comments on the blog recently showing I’m not the only person puzzling over these issues. With any luck we can all work together and beat this thing.

So what are the issues I think I need to be tackling first here?

  1. What’s going on with JT versions? As I commented in my last post here, there are three published versions: 8.1, 9.5, and ISO/DIS 14306. To the best of my knowledge, I’ve never seen a JT file which identified itself as being in one of those formats. But then, I haven’t been actively looking for several years. Is it too much to hope that everyone is using 9.5 and/or ISO/DIS 14306 now? (Is there even a difference between those two?)
  2. The great Huffman ambiguity issue. (Strangely, I don’t see signs I did a post on this?) Basically, there are cases where two subtrees have the same height, and as far as I know the specification does not say what to do then. The most recent JT work I’ve done was actually trying to compare what happened depending on what assumption I made here. But I got sidetracked before I actually made any progress on it.
  3. Does anyone out there actually have 9.5 files? I don’t know how fast it is taking over, but given that a version of 9.5 became an ISO standard two years ago, it certainly seems like a logical place to start.

I’m sure I’ll think of more things in short order.

Readers, do you have answers to any of these questions? Do you have questions of your own?

Update: Hey, I just grabbed a 9.5 file off of GrabCAD! It completely killed my importer, but still, that’s progress!

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2 Responses to Resuming JT Work

  1. Just having trouble too says:

    Hey there, thanks for sharing your work. A short question: Do you also have experience with implementing a writer (v8.1 or even v9.5)

    • colomon says:

      Unfortunately no. I usually wait until after I’ve got an importer working to look at implementing a writer, and my JT importer very definitely does not work yet.

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