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• Comment pourrions-nous améliorer le site piwik.org ? Retours, suggestions Feedback

  11 novembre 2011, par Piwik team — Communauté

  Bien que nous estimions que le site piwik.org remplit correctement son rôle, nous avons conscience qu’il peut être amélioré. Nous espérons de la sorte mieux servir la communauté Piwik.

  Dans un premier temps, nous avons l’intention de travailler sur une refonte du site piwik.org , qui contient les différentes documentations, des FAQs, le compteur de téléchargements, Participé au projet, et beaucoup d’autres pages.

  Quelles sont vos suggestions relatives à la refonte du site web ? Quelle apparence, impression doit-il avoir, etc.

  Veuillez nous présenter vos meilleures suggestions / vos retours constructifs, soit dans un commentaire posté sur notre blog, soit sur la page fan de Facebook, ou tout autre moyen dont vous disposeriez pour nous contacter. Merci à tous de nous faire profiter de vos suggestions !

  Bonne vie & analyses,
  L’équipe Piwik

• Turn image sequence into video with transparency

  29 janvier 2014, par Cody Hatch

  I've got what seems like it should be a really simple problem, but it's proving much harder than I expected. Here's the issue :

  I've got a fairly large image sequence consisting of numbered frames (output from Maya, for what its worth). The images are currently in Targa (.tga) format, but I could convert them to PNGs or other arbitrary format if that matters. The important thing is, they've got an alpha channel.

  What I want to do is programatically turn them into a video clip. The format doesn't really matter, but it needs to be lossless and have an alpha channel. Uncompressed video in a Quicktime container would probably be ideal.

  My initial thought was ffmpeg, but after wasting most of a day on it it seems it's got no support at all for alpha channels. Either I'm missing something, or the underlying libavcodec just doesn't do it.

  So, what's the right way here ? A command line tool like ffmpeg would be nice, but any solution that runs on Windows and could be called from a script would be fine.

  Note : Having an alpha chanel in your video isn't actually all that uncommon, and it's really useful if you want to composite it on top of another video clip or a still image. As far as I know uncompressed video, the Quicktime Animation codec, and the Sorenson Video 3 codec all support tranparency, and I've heard H.264 does as well. All we're really talking about is 32-bit color depth, and that's pretty widely supported ; both Quicktime .mov files and Windowss .avi files can handle it, and probably a lot more too.

  Quicktime Pro is more than happy to turn an image sequence into a 32-bit .mov file. Hit export, change color depth to "Millions of Colors+", select the Animation codec, crank the quality up to 100, and there you are - losslessly compressed video, with an alpha chanel, and it'll play back almost anywhere since the codec has been part of Quicktime since version 1.0. The problem is, Quicktime Pro doesn't have any sort of command-line interface (at least on Windows). ffmpeg supports encoding using the Quicktime Animation codec (which it calls qtrle), but it only supports a bit-depth of 24 bits.

  The issue isn't finding a video format that supports an alpha channel. Quicktime Animation would be ideal, but even uncompressed video should work. The problem is finding a tool that supports it.

• FFMPEG API : how to use lossless h264 encoding ?

  17 octobre 2012, par user1282931

  what settings are necessary to use h264 lossless encoding ? I'm not talking about ffmpeg commandline tool, but about the c api.

  I manage to encode video with lossy h264, but I don't know how to set the encoder to lossless.?

  I code in MSVC++ and use precompiled libraries. online i found some .ffpreset files (for example libx264-lossless_max.ffpreset) which don't seem to be part of the precompiled version i use (at least they are not in the presets folder). I'm not sure whether ffpreset files are somehow compiled into the library, or whether they can be loaded into the encoder somehow ? if so, how would I use such a preset file ?