Researching file formats 38: AppleDouble Resource Fork

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: AppleDouble Resource Fork. Comments welcome directly to the Library of Congress. AppleDouble……………………… Also known as “Dot underscore” files because that’s what they look like, ._likeThis. Are they related to .DS_Store files? Like, in a concrete way? What about MacBinary? macOS makes them. I don’t even want to...
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Researching file formats 37: Portable Embosser Format

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: Portable Embosser Format. Comments welcome directly to the Library of Congress. The Portable Embosser Format (PEF) is a document type that represents braille pages in digital form, “accurately and unambiguously; regardless of language, location, embosser settings, braille code and computer environment” (source). Not a lot of info...
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Researching file formats 36: Windows Phone Installation Package

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: Silverlight Application Package. Comments welcome directly to the Library of Congress. Okay, this was a fun one! If you remember using Netflix in the early-to-mid 2010s, you might remember having to download this extra thing called Silverlight in order to stream video. For reasons that I would...
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Researching file formats 35: Apple ProRaw

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: Apple ProRAW. Comments welcome directly to the Library of Congress. This blog post from Lux on “Understanding ProRaw” is useful not just in what it purports to do, but as an overall explainer for how digital cameras work these days. It’s great! And it explains the format...
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Researching file formats 34: iOS App Store Package

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: IPA. Comments welcome directly to the Library of Congress. Like last week’s post on the Android package, the iOS App Store Package is also… (dun dun dun)… just a ZIP archive file! It’s also not really well-disclosed, with no official docs from Apple that specify the .ipa...
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Researching file formats 33: Android Package

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: APK. Comments welcome directly to the Library of Congress. First off, this work was made incredibly easier thanks to the work of Johan van der Knijff, particularly the blog series around working with mobile apps, the latest being “Towards a preservation workflow for mobile apps” from 2021,...
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Researching file formats 27: Core Audio Format

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: Apple Core Audio Format. Comments welcome directly to the Library of Congress. Core Audio Format (CAF) is a file format for storing and transporting digital audio data. It’s published by Apple. Fully disclosed, thoroughly, with helpful contextual statements. It was introduced in 2005. I am a bit...
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Researching file formats 31: XYZ Point Cloud

This blog post is part of a series on file formats research. See this introduction post for more information. After a handful of difficult and technically (or socially/politically) complex formats, it was nice to work on this simple (if unspecified) format, taking me back to one of the earliest formats I worked on, FASTA. This format originally belonged in that initial category (see RGBE Image Format), but there was a mix-up. While it is structurally...
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Researching file formats 30: Autodesk Maya Binary

This blog post is part of a series on file formats research. See this introduction post for more information. You know, I saved a spot for this format but it really is essentially the same as last week’s, except stored in a binary format instead of a text-based one. I checked to see if it was simply gzipped, but it wasn’t – it’s its own secret-sauce thing courtesy of Autodesk (as usual, comments welcome, maybe...
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Researching file formats 29: Autodesk Maya Project

This blog post is part of a series on file formats research. See this introduction post for more information. This format described 3D scenes – geometry, lighting, animation, rendering, other stuff. It’s fairly straightforward, and I felt the documentation was relatively thorough while being succinct. Preservation issues seem to mostly be around concerns with this file needing to be connected to other files: Here’s what the specification has to say about this format: “If you...
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Researching file formats 28: Virtual Reality Modeling Language

This blog post is part of a series on file formats research. See this introduction post for more information. I was getting so overwhelmed surfing the old web for this format. It was absolutely thrilling but exhausting too, like when you’re on your 13th day of vacation and you’re so worn out but there’s so much more to see. Nothing is more exciting to me than looking into VIRTUAL WORLDS. I felt like it looked...
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Researching file formats 27: Microstation DGN

This blog post is part of a series on file formats research. See this introduction post for more information. This format was really a family of formats, and there’s specifically a break between an older version of the format, documented, and a later version of the format, semi-documented. At the time of writing this blog post, I still have some work to do in sorted out all the details and nuances here, when there’s not...
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Researching file formats 26: 3DM

This blog post is part of a series on file formats research. See this introduction post for more information. The next six formats are part of Set 3: 3D, VR and Animation! All of these formats are quite different from each other (except two closely related, which will be obvious). First up: 3DM. Rhino 3D Model file format family. Or the openNURBS 3D model? Something important to note off the top is that openNURBS is...
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Researching file formats 25: Nullsoft Streaming Video

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: Nullsoft Streaming Video. Comments welcome directly to the Library of Congress. “Support for more codecs will be added soon.” – Nullsoft, 2004 Last week was an audio codec, this week is an audio/video container. (See my training site for nuances there, if needed!) And it’s a container...
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Researching file formats 24: Unified Speech and Audio Coding

This blog post is part of a series on file formats research. See this introduction post for more information. Update: The official format definition is now online here: Unified Speech and Audio Coding. Comments welcome directly to the Library of Congress. Okay, this format was hard! First, the format is standardized via ISO/IEC, which means it’s expensive. Next, the specification is extremely long and technical, with lots of math. And this is my area of...
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