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Médias (1)
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La conservation du net art au musée. Les stratégies à l’Å“uvre
26 mai 2011
Mis à jour : Juillet 2013
Langue : français
Type : Texte
Autres articles (64)
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ANNEXE : Les plugins utilisés spécifiquement pour la ferme
5 mars 2010, parLe site central/maître de la ferme a besoin d’utiliser plusieurs plugins supplémentaires vis à vis des canaux pour son bon fonctionnement. le plugin Gestion de la mutualisation ; le plugin inscription3 pour gérer les inscriptions et les demandes de création d’instance de mutualisation dès l’inscription des utilisateurs ; le plugin verifier qui fournit une API de vérification des champs (utilisé par inscription3) ; le plugin champs extras v2 nécessité par inscription3 (...)
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Emballe médias : à quoi cela sert ?
4 février 2011, parCe plugin vise à gérer des sites de mise en ligne de documents de tous types.
Il crée des "médias", à savoir : un "média" est un article au sens SPIP créé automatiquement lors du téléversement d’un document qu’il soit audio, vidéo, image ou textuel ; un seul document ne peut être lié à un article dit "média" ; -
Gestion des droits de création et d’édition des objets
8 février 2011, parPar défaut, beaucoup de fonctionnalités sont limitées aux administrateurs mais restent configurables indépendamment pour modifier leur statut minimal d’utilisation notamment : la rédaction de contenus sur le site modifiables dans la gestion des templates de formulaires ; l’ajout de notes aux articles ; l’ajout de légendes et d’annotations sur les images ;
Sur d’autres sites (10173)
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Playing With File
8 septembre 2011, par Multimedia Mike — GeneralI played with the ‘file’ utility a long time ago because I wanted to make it recognize a large number of multimedia formats. I had trouble getting my changes to take. But I’m prepared to try again after many years.
Aiming at the Corpus
In my local mirror of the MPlayerHQ samples archive, I find 9853 unique files. So I run all of them through the ‘file’ command :’find /path/to/samples -type f -print0 | xargs -0 file —no-pad’
My Ubuntu installation has file v5.04. I also tested against 5.07 and the latest, 5.08. Here is the number of files each version was unable to identify (generically marking as ‘data’) :
5.04 1521 5.07 1405 5.08 1501
That seems like a regression for v5.08 until I dug into the details and saw quite a few items like this, indicating that the MPEG detection could use some work :
mov/mov-demux-infinite-loop.mpg : DOS-executable ( +mov/mg-‹demux-infinite-loop.mpg : data
image-samples/UNeedQT4.pntg : DOS-executable ( +imY- samples/UNeedQT4.pntg : data
Workflow
These are just notes to myself and perhaps anyone else who wants to add new file formats to be identified by the ‘file’ command.First, download either the latest release from the FTP or clone from Github. Do the usual unpack, ‘./configure’, ‘make’ routine. To use this newly-built version and its associated magic file :
./src/file —magic-file magic/magic.mgc <file>
To add a new format for ID, first, run the foregoing command to ensure that it’s not already identified. Then, check over the files in magic/Magdir and see which one might pertain to what you’re doing (it’s unlikely that your format will merit a new file in this directory). For example, for this round, I modified animation, audio, iff, and riff. Add or modify existing specs based on the copious examples in the directory and by consulting the appropriate man page (‘man 5 magic’).
Finally, run ‘make’ again which will regenerate the magic file. Invoke the above command again to use the modified magic file.
Before and After
On a selection of formats taken from the samples archive (renamed and cut down to a kilobyte because detection typically only relies on the first few bytes), here is the “before” :amv : RIFF (little-endian) data armovie : data bbc-dirac : data interplay-mve : data mtv : data nintendo-thp : data nullsoft-video : data redcode : data sega-film : data smacker : data trueaudio : data vqa : IFF data wavpack : data wc3-mve : IFF data wtv : data
And the “after” :
amv : RIFF (little-endian) data, AMV armovie : ARMovie bbc-dirac : BBC Dirac Video interplay-mve : Interplay MVE Movie mtv : MTV Multimedia File nintendo-thp : Nintendo THP Multimedia nullsoft-video : Nullsoft Video redcode : REDCode Video sega-film : Sega FILM/CPK Multimedia, 320 x 224 smacker : RAD Game Tools Smacker Multimedia version 2, 320 x 200, 100 frames trueaudio : True Audio Lossless Audio vqa : IFF data, Westwood Studios VQA Multimedia, 418 video frames, 320 x 200 wavpack : WavPack Lossless Audio wc3-mve : IFF data, Wing Commander III Video, PC version wtv : Windows Television DVR Media
After rerunning ‘file’ on the mphq corpus using the modified magic file, only 1329 files remain unidentified (down from 1501).
Going Forward
As mentioned, MPEG detection could probably be strengthened. However, a major weakness is QuickTime/MP4. Many files are not detected, probably owing to the many ways that QuickTime files can begin. -
What’s So Hard About Building ?
10 septembre 2011, par Multimedia Mike — ProgrammingI finally had a revelation as to why so building software can be so difficult– because build systems are typically built on programming languages that you don’t normally use in your day to day programming activities. If the project is simple enough, the build system usually takes care of the complexities. If there are subtle complexities — and there always are — then you can to figure out how to customize the build system to meet your needs.
First, there’s the Makefile. It’s easy to forget that the syntax which comprises a Makefile pretty well qualifies as a programming language. I wonder if it’s Turing-complete ? But writing and maintaining Makefiles manually is arduous and many systems have been created to generate Makefiles for you. At the end of the day, running ‘make’ still requires the presence of a Makefile and in the worst case scenario, you’re going to have to inspect and debug what was automatically generated for that Makefile.
So there is the widespread GNU build system, a.k.a., “the autotools”, named due to its principle components such as autoconf and automake. In this situation, you have no fewer than 3 distinct languages at work. You write your general build instructions using a set of m4 macros (language #1). These get processed by the autotools in order to generate a shell script (language #2) called configure. When this is executed by the user, it eventually generates a Makefile (language #3).
Over the years, a few challengers have attempted to dethrone autotools. One is CMake which configures a project using its own custom programming language that you will need to learn. Configuration generates a standard Makefile. So there are 2 languages involved in this approach.
Another option is SCons, which is Python-based, top to bottom. Only one programming language is involved in the build system ; there’s no Makefile generated and run. Until I started writing this, I was guessing that the Python component generated a Makefile, but no.
That actually makes SCons look fairly desirable, at least if your only metric when choosing a build system is to minimize friction against rarely-used programming languages.
I should also make mention of a few others : Apache Ant is a build system in which the build process is described by an XML file. XML doesn’t qualify as a programming language (though that apparently doesn’t stop some people from using it as such). I see there’s also qmake, related to the Qt system. This system uses its own custom syntax.
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How to Choose a GDPR Compliant Web Analytics Solution
2 mars 2022, par Matthieu Aubry — Privacy