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• FFMPEG : Video file to YUV conversion by binary ffmpeg and by code C++ give different results

  30 juin 2016, par Anny G

  Disclaimer : I have looked at the following question,
  FFMPEG : RGB to YUV conversion by binary ffmpeg and by code C++ give different results
  but it didn’t help and it is not applicable to me because I am not using SwsContext or anything.

  Following first few tutorials by http://dranger.com/ffmpeg/, I have created a simple program that reads a video, decodes it and then when the frame is decoded, it writes the raw yuv values to a file (no padding), using the data provided by AVFrame after we successfully decoded a frame. To be more specific, I write out arrays AVFrame->data[0], AVFrame->data[1] and AVFrame->data[2] to a file, i.e. I simply append Y values, then U values, then V values to a file. The file turns out to be of yuv422p format.

  When I convert the same original video to a raw yuv format using the ffmpeg(same version of ffmpeg) command line tool, the two yuv files are the same in size, but differ in content.

  FYI, I am able to play both of the yuv files using the yuv player, and they look identical as well.

  Here is the exact command I run to convert the original video to a yuv video using ffmpeg command line tool

   ~/bin/ffmpeg -i super-short-video.h264 -c:v rawvideo -pix_fmt yuv422p  "super-short-video-yuv422p.yuv"

  What causes this difference in bytes and can it be fixed ? Is there perhaps another way of converting the original video to a yuv using the ffmpeg tool but maybe I need to use different settings ?

  Ffmpeg output when I convert to a yuv format :

  ffmpeg version N-80002-g5afecff Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.1)
  
    configuration: --prefix=/home/me/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/me/ffmpeg_build/include --extra-ldflags=-L/home/me/ffmpeg_build/lib --bindir=/home/me/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree --extra-cflags=-pg --extra-ldflags=-pg --disable-stripping
  
    libavutil      55. 24.100 / 55. 24.100
  
    libavcodec     57. 42.100 / 57. 42.100
  
    libavformat    57. 36.100 / 57. 36.100
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 45.100 /  6. 45.100
  
    libswscale      4.  1.100 /  4.  1.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, h264, from 'super-short-video.h264':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: h264 (High), yuv420p, 1280x720, 25 fps, 25 tbr, 1200k tbn
  
  [rawvideo @ 0x24f6fc0] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
  
  Output #0, rawvideo, to 'super-short-video-yuv422p.yuv':
  
    Metadata:
  
      encoder         : Lavf57.36.100
  
      Stream #0:0: Video: rawvideo (Y42B / 0x42323459), yuv422p, 1280x720, q=2-31, 200 kb/s, 25 fps, 25 tbn
  
      Metadata:
  
        encoder         : Lavc57.42.100 rawvideo
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
  
  Press [q] to stop, [?] for help
  
  frame=   50 fps=0.0 q=-0.0 Lsize=   90000kB time=00:00:02.00 bitrate=368640.0kbits/s speed=11.3x    
  
  video:90000kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%

• How to create a custom processor for audio files in Ruby on Rails(5) with Paperclip

  11 novembre 2016, par Thomas Roest

  So I’m trying to convert mp3 files into .flac with Paperclip custom processors and ffmpeg. The following code runs the ffmpeg command and creates a temporary flac file. However, it is not saved ? Currently only the original file is saved. What am I missing here ?

  class AudioFile < ApplicationRecord
  
    has_attached_file :raw_audio, processors: [:custom], styles: { original: {}}

  the custom processor

  module Paperclip
  
   class Custom < Processor
  
  
  
    def initialize(file, options = {}, attachment = nil)
  
      super
  
      @file = file
  
      @basename = File.basename(@file.path)
  
      @format = options[:format] || 'flac'
  
      @params = options[:params] || '-y -i' 
  
    end
  
  
  
    def make
  
      source = @file
  
      output = Tempfile.new([@basename, ".#{@format}"])
  
      begin
  
        parameters = [@params, ':source',':dest'].join(' ')
  
        Paperclip.run('ffmpeg', parameters, :source => File.expand_path(source.path), :dest => File.expand_path(output.path), :sample_rate => @sample_rate, :bit_rate => @bit_rate)
  
      end
  
     output
  
    end
  
  
  
   end
  
  end

• Piwik 3 Development Update #1 – New UI design, API changes & release date

  1er septembre 2016, par Thomas Steur — Community, Development

  Over the last months, we have been actively working on the Piwik 3 release and we want to introduce you to the changes that we have done so far. They include a new and modern UI redesign, new widgets for your dashboard, and technical improvements under the hood.

  New Piwik 3 UI

  Based on Material Design we have revamped the user interface which is now more responsive, more usable and faster. While the UI is not yet finished, we invite you to check it out already and to let us know what you think.

  

  This new Piwik material design is a visual language that synthesizes classic principles of good design with the innovation and possibility of technology and science.

  More responsive

  Piwik 3 will look and feel much better on your mobile phone and tablet. Many elements have been improved : the menus, the segment editor and dashboard selector, the widgets, the settings pages and most other pages so you can fully experience and enjoy Piwik on any device !

  

  Improved usability

  We have updated the menu structure, the dashboard selector as well as the footer in reports to make your life easier when using Piwik. We love to keep these complicated things simple. There are also many other tiny improvements that you will appreciate.

  

  The Zen Mode lets you view in full screen your analytics reports and dashboards. Users love this feature and it can now be accessed by pressing “z” key.

  

  Faster

  To make the Piwik interface faster, we have refactored most of our CSS, HTML and JavaScript and moved more and more of our code into the client. As a result, Piwik now needs to reload the page much less often ! For example when you change the date or change the segment, Piwik will now load the reports instantly. To improve performance even further, Piwik will now load multiple reports on a single page in parallel.

  Native fonts

  Over the last months more and more web services have started using system fonts, and so will Piwik 3. System fonts look better, improve language support and give you a more native, familiar feeling.

  For more details and screenshots have a look at the pull request for the Piwik 3 UI update.

  New widgets

  With the “Latest Piwik Plugin Updates” widget you won’t miss any newly added or updated plugin anymore. This will help you learn about and discover the useful plugins and themes available on the Marketplace.

  

  Super users can now see at a glance the current state of the Piwik system, thanks to the new “System Check” and “System Summary” widgets.

  

  API Changes

  Piwik is the leading open analytics platform, highly customisable and extensible thanks to a flexible plugins architecture and a design based on APIs. In this new major Piwik 3 release, we significantly improve the foundation of our open platform and several of its core APIs.

  The new Widgets and Reporting API makes it possible to add reports and widgets to any existing reporting page. In the past, reporting pages had to be created manually which was time consuming and it was hard to maintain a consistent look across different reporting pages. Now reporting pages are generated automatically by the Piwik platform.

  The Plugin Settings API was changed to improve performance and to let plugin developers customize the Websites Manager. This is one step towards our goal to let users not only manage websites but also mobile apps, cars, coffee machines or any other thing.

  To see a full list of changes in the Piwik 3 analytics platform, have a look at the developer changelog.

  Developer docs

  The Piwik Developer Zone is full of guides and API references to help developers understand, integrate and extend Piwik. As some APIs have changed in the Piwik 3 release it is now possible to select the Piwik version in the top right corner of the developer zone.

  

  We are updating guides for Piwik 3 and added a Piwik 2 -> Piwik 3 Migration Guide for plugin developers. Many other guides were updated such as Menus, Custom Report and Widgets.

  Release date

  The first Piwik 3 beta release will be available in the next four weeks. Beta testers automatically receive the update if they are subscribed to the “Latest Beta” release channel. The final Piwik 3 release will be ready before the end of the year. If you want to give it a try, you can either use Piwik from Git and check out the “3.x-dev” branch, or download Piwik 3 from GitHub.

  Closing thoughts

  With faster & more beautiful reports, better APIs and more stability, Piwik 3 is a big step forward for all Piwik users. As our mission is to create, as a community, the leading international open source web analytics platform that gives every user full control of their data, we are very excited to introduce you to this upcoming release.

  We now offer Custom Development services if you like to sponsor a new feature or bug fix, or if you have any custom requirements. And if you use Piwik Analytics to grow your business and need quality help, contact the Piwik analytics experts to get started.

  Until our next Piwik 3 dev update, Happy analysis !