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• slowing down a video with ffmpeg

  20 août 2014, par jeet

  I’m making a video using ffmpeg & multiple images with this command :

  ffmpeg -f image2 -i img%d.png v.mpg

  The video is made, but plays very fast. Can I slow it down a bit ? (double duration nearly)
  If possible set the speed while creation itself please.

  I also need to add an audio "a.wav" to the video being made, possibly in the same command. Is that possible ?

  Please give me the commands
  Thanks

  When I use this command, below is the error I get :

  ffmpeg -r 12 -i pic\s%d.png -i rmt.wav -shortest -r 25 v.mpg
  
  
  
  
  
  
  
  FFmpeg version SVN-r16573, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  
  configuration: --extra-cflags=-fno-common --enable-memalign-hack --enable-pthreads --enable-libmp3lame --enable-libxvid --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libfaac --enable-libgsm --enable-libx264 --enable-libschroedinger --enable-avisynth --enable-swscale --enable-gpl
  
  libavutil     49.12. 0 / 49.12. 0
  
  libavcodec    52.10. 0 / 52.10. 0
  
  libavformat   52.23. 1 / 52.23. 1
  
  libavdevice   52. 1. 0 / 52. 1. 0
  
  libswscale     0. 6. 1 /  0. 6. 1
  
  built on Jan 13 2009 02:57:09, gcc: 4.2.4
  
  Input #0, image2, from 'pic\s%d.png':
  
  Duration: 00:03:53.00, start: 0.000000, bitrate: N/A
  
  Stream #0.0: Video: png, rgb24, 1366x768, 12.00 tb(r)
  
  Input #1, wav, from 'rmt.wav':
  
  Duration: 00:12:16.19, bitrate: 64 kb/s
  
  Stream #1.0: Audio: pcm_u8, 8000 Hz, mono, s16, 64 kb/s
  
  Stream #0.0: Video: mpeg1video, yuv420p, 1366x768, q=2-31, 200 kb/s, 25.00 tb(c)
  
  Stream #0.1: Audio: mp2, 8000 Hz, mono, s16, 64 kb/s
  
  Stream mapping:
  
  Stream #0.0 -> #0.0
  
  Stream #1.0 -> #0.1
  
  [mp2 @ 0x1738390]Sampling rate 8000 is not allowed in mp2
  
  Error while opening codec for output stream #0.1 - maybe incorrect parameters such as bit_rate, rate, width or height

• ffmpeg capture output from child window

  3 janvier 2013, par glitchyme

  using xwininfo -all I'm able to see the stats of any window, along with its child windows

  xwininfo: Window id: 0x3c000ba "Electro - The Slag & Prototype Raptor - Crescendo - YouTube - Mozilla Firefox"
  
  
  
    Root window id: 0xa8 (the root window) (has no name)
  
    Parent window id: 0xc001b8 (has no name)
  
       2 children:
  
       0x3c00175 (has no name): ()  1388x876+0+0  +52+24
  
          5 children:
  
          0x3d210ab (has no name): ()  854x510+225+197  +277+221
  
             1 child:
  
             0x3d210ac (has no name): ()  854x510+0+0  +277+221
  
                1 child:
  
                0x40404de "plugin-container": ("plugin-container" "Plugin-container")  854x510+0+0  +277+221
  
                   2 children:
  
                   0x40404e1 (has no name): ()  854x510+0+0  +277+221
  
                   0x40404df (has no name): ()  1x1+-1+-1  +276+220
  
          0x3ddbcf2 (has no name): ()  640x390+225+162  +277+186
  
             1 child:
  
             0x3ddbcf3 (has no name): ()  640x390+0+0  +277+186
  
                1 child:
  
                0x403d545 "plugin-container": ("plugin-container" "Plugin-container")  640x390+0+0  +277+186
  
                   2 children:
  
                   0x403d548 (has no name): ()  640x390+0+0  +277+186
  
                   0x403d546 (has no name): ()  1x1+-1+-1  +276+185
  
          0x3dac7f9 (has no name): ()  640x390+225+162  +277+186
  
             1 child:
  
             0x3dac7fa (has no name): ()  640x390+0+0  +277+186
  
                1 child:
  
                0x4039d8b "plugin-container": ("plugin-container" "Plugin-container")  640x390+0+0  +277+186
  
                   2 children:
  
                   0x4039d8e (has no name): ()  640x390+0+0  +277+186
  
                   0x4039d8c (has no name): ()  1x1+-1+-1  +276+185
  
          0x3c3f939 (has no name): ()  640x390+225+197  +277+221
  
             1 child:
  
             0x3c3f93a (has no name): ()  640x390+0+0  +277+221
  
                1 child:
  
                0x4011918 "plugin-container": ("plugin-container" "Plugin-container")  640x390+0+0  +277+221
  
                   2 children:
  
                   0x401191b (has no name): ()  640x390+0+0  +277+221
  
                   0x4011919 (has no name): ()  1x1+-1+-1  +276+220
  
          0x3c0d1dc (has no name): ()  1x1+0+97  +52+121
  
             1 child:
  
             0x3c0d1dd (has no name): ()  1x1+0+0  +52+121
  
                1 child:
  
                0x4002c1e "plugin-container": ("plugin-container" "Plugin-container")  1x1+0+0  +52+121
  
                   2 children:
  
                   0x4002c40 (has no name): ()  1x1+0+0  +52+121
  
                   0x4002c1f (has no name): ()  1x1+-1+-1  +51+120
  
       0x3c000bb (has no name): ()  1x1+-1+-1  +51+23
  
  
  
    Absolute upper-left X:  52
  
    Absolute upper-left Y:  24
  
    Relative upper-left X:  0
  
    Relative upper-left Y:  0
  
    Width: 1388
  
    Height: 876
  
    Depth: 24
  
    Visual: 0x23
  
    Visual Class: TrueColor
  
    Border width: 0
  
    Class: InputOutput
  
    Colormap: 0x20 (installed)
  
    Bit Gravity State: NorthWestGravity
  
    Window Gravity State: NorthWestGravity
  
    Backing Store State: NotUseful
  
    Save Under State: no
  
    Map State: IsViewable
  
    Override Redirect State: no
  
    Corners:  +52+24  -0+24  -0-0  ç0
  
    -geometry 1388x876-0-0
  
  
  
    Bit gravity: NorthWestGravity
  
    Window gravity: NorthWestGravity
  
    Backing-store hint: NotUseful
  
    Backing-planes to be preserved: 0xffffffff
  
    Backing pixel: 0
  
    Save-unders: No
  
  
  
    Someone wants these events:
  
        KeyPress
  
        KeyRelease
  
        ButtonPress
  
        ButtonRelease
  
        EnterWindow
  
        LeaveWindow
  
        PointerMotion
  
        Exposure
  
        VisibilityChange
  
        StructureNotify
  
        FocusChange
  
        PropertyChange
  
    Do not propagate these events:
  
    Override redirection?: No
  
  
  
    Window manager hints:
  
        Client accepts input or input focus: Yes
  
        Initial state is Normal State
  
        Displayed on desktop 0
  
        Window type:
  
            Normal
  
        Window state:
  
            Maximized Vert
  
            Maximized Horz
  
        Process id: 4087 on host jb
  
        Frame extents: 0, 0, 0, 0
  
  
  
    Normal window size hints:
  
        Program supplied minimum size: 18 by 97
  
        Program supplied maximum size: 1073741824 by 1073741824
  
        Program supplied window gravity: NorthWestGravity
  
    No zoom window size hints defined
  
  
  
    No window shape defined
  
    No border shape defined

  However, if I try capturing from the screen given the size and offset of the child window, then I risk losing data when another window floats ontop of it, I switch to another tab while recording, I resize the child window, or move the child window. Instead, I'd like to use ffmpeg to capture from specifically that child window.

  Ideas ? Tips ? Maybe some other hacks to accomplish this ? Thanks :)

• Piwik Analytics and becoming a Piwik Certified Professional

  10 juillet 2017, par Piwik Core Team — About

  Digital Analytics software

  Piwik Analytics is the leading open source digital analytics software, offering users around the world an opportunity to liberate their analytics. Most recently, they have introduced the Piwik Certified Professional certification exam which now allows users to become qualified in Piwik Analytics software on an individual level to gain a deeper understanding of Piwik. In this blog post I will guide you through the topics that are covered during the exam and provide you with advice on taking the official Piwik Certified Professional exam.

  

  Piwik certification exam

  Taking the exam will cost you a maximum investment of 60 minutes of your time, besides learning all materials of course. The exam consists of 55 multiple choice questions with four answers to choose from. The score needed to pass is 80% (44 questions answered correctly) and the cost is 50 USD total. An earned certificate is valid for 18 months, before these eighteen months are over a person should pass the exam again in order to retain the certified status.

  Learning topics

  The exam consists of two sections. The main section is focused on the Piwik Analytics software itself while the second part relates to digital analytics in general. All topics and content covered about Piwik Analytics is available through the official Piwik user guides. The second section tests your experience as a digital analyst, online marketer or any other function title in which you work with Piwik Analytics. In this case, the general digital analytics questions should be quite straightforward and easy to answer, and cover only a fraction of the total questions in the exam (around 10% with 5-7 general questions). An outline of all exam topics are listed below :

  • A Tour of Piwik
  • Track Goals and Measure Conversions
  • Event Tracking
  • Content Tracking
  • Ecommerce Analytics
  • Row Evolution – View and compare historical data
  • Segmentation – Compare segments of visitors
  • Visitors Maps – World, region, city
  • Real Time Visitor World Map
  • Real Time Analytics
  • The Visitor Profile
  • Site speed and Page speed
  • Site Search Tracking and Reporting
    
  • Transitions – Analyze the previous and following actions of your visitors for each page
  • Page Overlay
  • Custom Variables Analytics
  • Custom Dimensions
  • User ID
  • Annotating your data
  • Tracking Campaigns
  • URL Builder for Marketing Campaign Tracking

  The best way to prepare for the exam is read the entire Piwik user guides. You should definitely read the “Analytics Features” section since most questions of the Piwik Certified Professional – Digital Analytics exam that will be asked come from these sections. Furthermore you should be able to find your way around in Piwik at a basic level which means you know what the reports mean and where to find certain information. In addition, some basic knowledge regarding the settings is useful too. The exam is definitely not a technical implementation exam so no coding knowledge or any other deeply technical knowledge regarding Piwik is required.

  Finally, some general questions will be asked regarding digital analytics covering topics about KPI’s and the role of the analyst within an organization. While Piwik provides some links to articles by Avinash Kaushik covering these topics, you will not be able to learn these topics just by reading. When you have some experience with digital analytics you should be able to answer these general digital analytics questions with common sense and (even basic) experience as a digital analyst, analytics consultant, online marketer or any other related job whereby you work with Piwik.

  Taking the exam

  With 55 questions to be answered in 60 minutes the key to passing the exam is to keep moving. You have about 1 minute and 5 seconds to answer each question. This means that you should focus on the easiest questions first and return later to the questions that are a bit more challenging to answer. Keep an eye on the timer that will be displayed in the exam window. When the time expires or you click ‘Finish test’ your exam will end and be automatically submitted for review. Remember to first check all questions and answers before you click on the ‘Finish test’ button. If you click too soon and you still haven’t answered all questions, all unanswered questions will be marked as incorrect.

  During the test, no hard copy or online materials may be referenced. As you can imagine, it is almost impossible to check if users reference these kind of materials. However, be aware of the penalty system that is in place during the test. When a user leaves from the active test screen to another screen (i.e. a different browser tab) the screen turns red and provides a warning count when the user returns to the test screen again. You will have three warnings, after this your test will be submitted and graded as false. Furthermore, keep in mind you will have to do the test in one go and cannot pause and come back another time.

  Practice makes perfect

  Below I have included some example questions that could be asked during the exam. These questions do not necessarily represent how Piwik will test you on these topics.

  • What is the default report date that is selected by Piwik ?
  • Why would someone flatten a report in Piwik ?
  • Why would a user especially use the Page Overlay report ?
  • What are the three main Ecommerce interactions tracked with Piwik ?
  • What is an example of an anonymized IP address in Piwik ?

  Passing the Piwik Certified Professional – Digital Analytics exam

  Directly after submitting the exam you will receive a notification telling you whether or not you have passed the exam. If you pass, you will be able to download your personal certification right away. A report of your exam performance will also be available. This report lists the amount of correct answers and total questions by topic. The report with your exam performance is also available if you did not pass the exam. The certificate is valid for 18 months from the date of successful completion.

  Sometimes the difference between passing and failing can be a matter of how you interpret some of Piwik’s questions. There are several tricky questions included, so be sure to pay attention to detail on every question. If you fail, you may take the exam again. You will have to pay the 50 USD fee for each try, so do your best to pass it the first time.

  → Register to become a Piwik Certified Professional.

  We wish you the best of luck and happy analytics !