Recherche avancée

Sur d’autres sites (11147)

• Web-based video editor

  10 octobre 2014, par Danny

  We have a web-based editor currently that allows users to build animated web apps. The apps are made up of shapes, text, images, and videos. Except for videos, all other elements can also be animated around the screen. The result of building a animated app is basically a big blob of JSON.

  The playback code for the web app is web-based as well. It takes the JSON blob and constructs the HTML, which ends up playing back in some sort of browser environment. The problem is that most of the time this playback occurs on lower-end hardware like televisions and set-top boxes.

  These performance issues go away if there is some way to be able to convert a digital sign to video. Then the STB/smart TV simply plays a video, which is much more performant than playing back animations in a web view.

  Given a blob of JSON describing each layer and how to draw each type of object, its animation points, etc, how could I somehow take that and convert it to video on the server ?

  My first attempt at this was using PhantomJS to load the playback page in a headless browser, take a series of screenshots, and then use ffmpeg to merge those screenshots into a video. That worked great so long as there is no video. But it does not work with video since there is no HTML5 video tag support in PhantomJS, and even if there was, I would lose any audio.

  The other way I was thinking of doing it would be to again load the playback page in PhantomJS, but turn off the video layers and leave them transparent, then take screenshots as a series of PNGs with transparency. I would then combine these with the video layers.

  None of this feels very elegant though. I know there are web-based video editors out there that basically do what I’m trying to accomplish, so how do they do it ?

• How to create a custom theme in Piwik – Introducing the Piwik Platform

  23 août 2014, par Thomas Steur — Development

  This is the start of a new blog series where we introduce the capabilities of the Piwik platform. You’ll learn how to write custom plugins & themes, how to use our HTTP APIs and more.

  We have been greatly simplifying our APIs over the last year focusing primarily on one design principle :

  The complexity of our API should never exceed the complexity of your use case.

  In other words, if you have a simple use for our API, we want it to be simple for you to accomplish it. If you have a complex, big, hairy, change-the-world idea, then maybe we can’t make it simple for you to accomplish it, but we want it to be possible.

  Over the next weeks and months you will learn what exactly we mean by this and how we accomplished it.

  FYI, don’t worry if you’re currently using our APIs, we keep them backwards compatible and we announce breaking changes in our platform changelog.

  Getting started

  In this series of posts, we assume that you have already set up your development environment. If not, visit the Piwik Developer Zone where you’ll find the tutorial Setting up Piwik.

  To summarize the things you have to do to get setup :

  • Install Piwik (for instance via git).
  • Activate the developer mode : ./console development:enable --full.
  • And if you want, generate some test data : ./console visitorgenerator:generate-visits --idsite=1 --limit-fake-visits=600. This can take a while and requires the VisitorGenerator plugin from the Marketplace.

  Let’s start creating our own theme

  We start by using the Piwik Console to create a blank theme :

  ./console generate:theme

  The command will ask you to enter a name, description and version number for your theme. I will simply use “CustomTheme” as the name of the theme. There should now be a folder plugins/CustomTheme which contains some files to get you started easily.

  Before we modify our theme, we have to activate it by visiting the Settings => Themes admin page in our Piwik installation, or alternatively by running the command ./console core:plugin activate YourCustomTheme. If the theme is not activated, we won’t see any changes.

  Theme Contents

  The most important files in our theme are plugins/CustomTheme/stylesheets/theme.less, plugins/CustomTheme/stylesheets/_colors.less and plugins/CustomTheme/stylesheets/_variables.less :

  • theme.less is the file that will be included when your theme is activated. In this file you would include other stylesheet files and overwrite CSS styles.
  • _colors.less contains many less variables allowing you to easily change the colors Piwik uses.
  • _variables.less contains currently only one variable to change the font family. More variables will be added in the future. Note : This is a new feature and the file will be only there in case you have installed Piwik using Git or at least Piwik 2.6.0.

  Changing the font family

  To change the font family simply overwrite the variable @theme-fontFamily-base: Verdana, sans-serif; in _variables.less. That’s it.

  Changing colors

  To change a color, uncomment the less variables of the colors you want to change in _colors.less. I will shortly explain some of them. Usually changing only these colors will be enough to adjust Piwik’s look to your corporate design or to create a look that pleases you :

  @theme-color-brand:                    #d4291f; // The Piwik red which is for instance used in the menu, it also defines the color of buttons, the little arrows and more
  
  @theme-color-brand-contrast:           #ffffff; // Contrast color to the Piwik red. Usually you need to change it only in case you define a light brand color. For instance to change the text color of buttons
  
  @theme-color-link:                     #1e93d1; // The link color which is usually a light blue
  
  
  
  @theme-color-widget-title-text:        #0d0d0d; // The text and background color of the header of a widget (Dashboard)
  
  @theme-color-widget-title-background:  #f2f2f2;
  
  
  
  @theme-color-menu-contrast-text:       #666666; // The text color of a menu item in the reporting sub menu and the admin menu
  
  @theme-color-menu-contrast-textActive: #0d0d0d; // The text color of an active menu item
  
  @theme-color-menu-contrast-background: #f2f2f2; // The background color of a menu item
  
  
  
  @graph-colors-data-series[1-8]:        #000000; // The different colors used in graphs

  Making the change visible

  To make a color or font change actually visible when you reload a page in Piwik you will have to delete the compiled CSS file after each change like this :

  rm tmp/assets/asset_manager_global_css.css

  Publishing your Theme on the Marketplace

  In case you want to share your theme with other Piwik users you can do this by pushing your theme to GitHub and creating a tag. Easy as that. Read more about how to distribute a theme.

  Advanced features

  Isn’t it easy to create a custom theme ? All we had to do is to change some less variables. We never even created a file ! Of course, based on our API design principle, you can accomplish more if you want. For instance, you can change icons, CSS stylesheets, templates and more.

  For further customising your Piwik, you can even change the logo and favicon in the Settings => General settings page.

  Would you like to know more about theming ? Go to our Theme guide in the Piwik Developer Zone.

  If you have any feedback regarding our APIs or our guides in the Developer Zone feel free to send it to us.

  PS : see also this related FAQ : How do I White Label Piwik ?

• FFMPEG - How to setup volume when merging two audio streams

  6 octobre 2014, par N3sh

  I just recently entered the magic and scary world of FFMPEG and, although I found quite a lot of guides online, I need help for my current problem.

  I am merging only audio files and I would like to be able to select their volume.

  Here is my current code for merging 2 files :

  ffmpeg -i test\audio00.mp3 -i test\audio01.mp3 -filter_complex amerge 
  
  -c:a libmp3lame -q:a 0 test\output_overlay.mp3

  I tried the following code, extracted from another answer here on SO (the User was also handling video), but it doesn’t work for me :

  ffmpeg -i test\audio00.mp3 -i test\audio01.mp3 -filter_complex "[0:a]volume=0.9[a1];  
  
  [1:a]volume=0.781250[a2]; [a1][a2]amerge,pan=stereo:c0code>

  I got this error :

  [AVFilterGraph @ 030fa8c0] The following filters could not choose their formats: 
  
  Parsed_amerge_2 Consider inserting the (a)format filter near their input or output.

  Is there a simple way to change the volume for the two streams (even for just the second one, it’s the background music) with FFMPEG ?

  P.S. Also, is it possible to have some sort of ’preview’ before actually rendering the file ?