# format_parser is a Ruby library for prying open video, image, document, and audio files. It includes a number of parser modules that try to recover metadata useful for post-processing and layout while reading the absolute minimum amount of data possible. `format_parser` is inspired by [imagesize,](https://rubygems.org/gem/imagesize) [fastimage](https://github.com/sdsykes/fastimage) and [dimensions,](https://github.com/sstephenson/dimensions) borrowing from them where appropriate. [![Gem Version](https://badge.fury.io/rb/format_parser.svg)](https://badge.fury.io/rb/format_parser) [![Build Status](https://travis-ci.org/WeTransfer/format_parser.svg?branch=master)](https://travis-ci.org/WeTransfer/format_parser) ## Currently supported filetypes: * TIFF * CR2 * NEF * PSD * PNG * MP3 * JPEG * GIF * PDF * DPX * AIFF * WAV * FLAC * FDX * MOV * MP4 * M4A * ZIP * DOCX, PPTX, XLSX * OGG * MPEG, MPG * M3U * WEBP ...with [more](https://github.com/WeTransfer/format_parser/issues?q=is%3Aissue+is%3Aopen+label%3Aformats) on the way! ## Basic usage Pass an IO object that responds to `read`, `seek` and `size` to `FormatParser.parse` and the first confirmed match will be returned. ```ruby match = FormatParser.parse(File.open("myimage.jpg", "rb")) match.nature #=> :image match.format #=> :jpg match.display_width_px #=> 320 match.display_height_px #=> 240 match.orientation #=> :top_left ``` You can also use `parse_http` passing a URL or `parse_file_at` passing a path: ```ruby match = FormatParser.parse_http('https://upload.wikimedia.org/wikipedia/commons/b/b4/Mardin_1350660_1350692_33_images.jpg') match.nature #=> :image match.format #=> :jpg ``` If you would rather receive all potential results from the gem, call the gem as follows: ```ruby array_of_results = FormatParser.parse(File.open("myimage.jpg", "rb"), results: :all) ``` You can also optimize the metadata extraction by providing hints to the gem: ```ruby FormatParser.parse(File.open("myimage", "rb"), natures: [:video, :image], formats: [:jpg, :png, :mp4], results: :all) ``` Return values of all parsers have built-in JSON serialization ```ruby img_info = FormatParser.parse(File.open("myimage.jpg", "rb")) JSON.pretty_generate(img_info) #=> ... ``` To convert the result to a Hash or a structure suitable for JSON serialization ```ruby img_info = FormatParser.parse(File.open("myimage.jpg", "rb")) img_info.as_json # it's also possible to convert all keys to string img_info.as_json(stringify_keys: true) ``` ## Creating your own parsers See the [section on writing parsers in CONTRIBUTING.md](CONTRIBUTING.md#so-you-want-to-contribute-a-new-parser) ## Design rationale We need to recover metadata from various file types, and we need to do so satisfying the following constraints: * The data in those files can be malicious and/or incomplete, so we need to be failsafe * The data will be fetched from a remote location (S3), so we want to obtain it with as few HTTP requests as possible * ...and with the amount of data fetched being small - the number of HTTP requests being of greater concern * The data can be recognized ambiguously and match more than one format definition (like TIFF sections of camera RAW) * The information necessary is a small subset of the overall metadata available in the file. * The number of supported formats is only ever going to increase, not decrease * The library is likely to be used in multiple consumer applications * The library is likely to be used in multithreading environments ## Deliberate design choices Therefore we adapt the following approaches: * Modular parsers per file format, with some degree of code sharing between them (but not too much). Adding new formats should be low-friction, and testing these format parsers should be possible in isolation * Modular and configurable IO stack that supports limiting reads/loops from the source entity. The IO stack is isolated from the parsers, meaning parsers do not need to care about things like fetches using `Range:` headers, GZIP compression and the like * A caching system that allows us to ideally fetch once, and only once, and as little as possible - but still accomodate formats that have the important information at the end of the file or might need information from the middle of the file * Minimal dependencies, and if dependencies are to be used they should be very stable and low-level * Where possible, use small subsets of full-feature format parsers since we only care about a small subset of the data. * When a choice arises between using a dependency or writing a small parser, write the small parser since less code is easier to verify and test, and we likely don't care about all the metadata anyway * Avoid using C libraries which are likely to contain buffer overflows/underflows - we stay memory safe ## Acknowledgements We are incredibly grateful to Remco van't Veer for [exifr](https://github.com/remvee/exifr) and to Krists Ozols for [id3tag](https://github.com/krists/id3tag) that we are using for crucial tasks. ## Fixture Sources Unless specified otherwise in this section the fixture files are MIT licensed and from the FastImage and Dimensions projects. ### JPEG - `divergent_pixel_dimensions_exif.jpg` is used with permission from LiveKom GmbH - `extended_reads.jpg` has kindly been made available by Raphaelle Pellerin for use exclusively with format_parser - `too_many_APP1_markers_surrogate.jpg` was created by the project maintainers * `orient_6.jpg` is used with permission from [Renaud Chaput](https://github.com/renchap) ### AIFF - fixture.aiff was created by one of the project maintainers and is MIT licensed ### WAV - c_11k16bitpcm.wav and c_8kmp316.wav are from [Wikipedia WAV](https://en.wikipedia.org/wiki/WAV#Comparison_of_coding_schemes), retrieved January 7, 2018 - c_39064__alienbomb__atmo-truck.wav is from [freesound](https://freesound.org/people/alienbomb/sounds/39064/) and is CC0 licensed - c_M1F1-Alaw-AFsp.wav and d_6_Channel_ID.wav are from a [McGill Engineering site](http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Samples.html) ### MP3 - Cassy.mp3 has been produced by WeTransfer and may be used with the library for the purposes of testing ### AAC - Originals music files: “Furious Freak” and “Galway”, Kevin MacLeod (incompetech.com), Licensed under Creative Commons: By Attribution 3.0, http://creativecommons.org/licenses/by/3.0/ - The AAC samples were converted from 'wav' format and made available [here](https://espressif-docs.readthedocs-hosted.com/projects/esp-adf/en/latest/design-guide/audio-samples.html) by Espressif Systems, as part of their audio development framework (under the ESPRESSIF MIT License). - Files: - ff-16b-2c-44100hz.aac - ff-16b-1c-44100hz.aac - gs-16b-2c-44100hz.aac - gs-16b-1c-44100hz.aac ### FDX - fixture.fdx was created by one of the project maintainers and is MIT licensed ### DPX - DPX files were created by one of the project maintainers and may be used with the library for the purposes of testing ### MOOV - bmff.mp4 is borrowed from the [bmff](https://github.com/zuku/bmff) project - Test_Circular MOV files were created by one of the project maintainers and are MIT licensed ### CR2 - CR2 examples are downloaded from http://www.rawsamples.ch/ and are Creative Common Licensed. ### NEF - NEF examples are downloaded from http://www.rawsamples.ch/ and are Creative Common Licensed. ### ERF - ERF examples are downloaded from http://www.rawsamples.ch/ and are Creative Common Licensed. ### FLAC - atc_fixture_vbr.flac is a converted version of the MP3 with the same name - c_11k16btipcm.flac is a converted version of the WAV with the same name ### OGG - `hi.ogg`, `vorbis.ogg`, `with_confusing_magic_string.ogg`, `with_garbage_at_the_end.ogg` have been generated by the project contributors ### M4A - fixture.m4a was created by one of the project maintainers and is MIT licensed ### PNG - `simulator_screenie.png` provided by [Rens Verhoeven](https://github.com/renssies) ### TIFF - `Shinbutsureijoushuincho.tiff` is obtained from Wikimedia Commons and is Creative Commons licensed - `IMG_9266_*.tif` and all it's variations were created by the project maintainers ### ARW - ARW examples are downloaded from http://www.rawsamples.ch/ and are Creative Common Licensed. ### ZIP - The .zip fixture files have been created by the project maintainers ### .docx - The .docx files were generated by the project maintainers ### .mpg and .mpeg - The files (video 1 to 4) were downloaded from https://standaloneinstaller.com/blog/big-list-of-sample-videos-for-testers-124.html. - Video 5 was downloaded from https://archive.org/details/ligouHDR-HC1_sample1. ### JPEG examples of EXIF orientation - Downloaded from Unspash (and thus freely avaliable) - https://unsplash.com/license and have then been manipulated using the [https://github.com/recurser/exif-orientation-examples](exif-orientation-examples) script. ### M3U - The M3U fixture files were created by one of the project maintainers ### WEBP - With the exception of extended-animation.webp, which was obtained from Wikimedia Commons and is Creative Commons licensed, all of the WebP fixture files have been created by one of the project maintainers. ### .key - The `keynote_recognized_as_jpeg.key` file was created by the project maintainers ## Copyright Copyright (c) 2020 WeTransfer. `format_parser` is distributed under the conditions of the [Hippocratic License](https://firstdonoharm.dev/version/1/2/license.html) - See LICENSE.txt for further details.