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• FFmpeg producing a flickering video from images

  21 juin 2018, par jjohnn91

  So I’m trying to make a video of a fractal rotating through some values, much like seen here.

  I generate the frames (1000 of them) using a different program written in Java that works just fine, so for the purposes of this scenario assume that all the images are in the target folder and also in numerical order as they need to appear in the video.

  I found the following code on the web to stitch images into a video, and I haven’t the faintest idea how it works, and when I run it, all of the images are indeed stitched into a video and placed on the desktop, but the video appears to have one specific frame just jump in at random positions. I’m not totally sure which one, but its one of the earlier frames, somewhere between 1 and 200 of the 1000.

  I’ve also tested making two half videos, one using the first 500 frames, and the other using the second 500 frames. The first video (1 -> 500) has flickering, and the second video (501 -> 1000) appears not to have flickering to my observations.

  I am seeking help in fixing the flickering behavior, and I will upload the video file to google drive later if asked. The Images are all 1920x1080, and in proper numerical order.

  Thanks in advance !

  import static org.bytedeco.javacpp.opencv_imgcodecs.*;
  
  import java.io.File; 
  
  import org.bytedeco.javacpp.avcodec;
  
  import org.bytedeco.javacv.FFmpegFrameRecorder;
  
  import org.bytedeco.javacv.OpenCVFrameConverter;
  
  public class ImageToMovie{
  
      public static void main(String []args){
  
          String imgPath="C:\\Users\\John\\Images";
  
          String vidPath="C:\\Users\\John\\Desktop\\video.mp4";
  
          String[] links=new String[new File(imgPath).listFiles().length];
  
          File f=new File(imgPath);
  
          File[] f2=f.listFiles();
  
          for(int i=0;icode>

• ffmpeg volumedetect returns unstable result

  8 février 2018, par Eric Stdlib

  I am using ffmpeg to calculate the volume of my audio file, but I find that ffmpeg returns different values for different containers (like mp3 v.s. ogg)

  Here is an example. I am using an ogg file from Wikimedia Commons, and converting it to mp3, then analyze the volume of both files. For ogg file, I get -3.0 dB for mean volume, but for mp3 file, I get -3.4 dB. When I use other files, I also get different max volume and histogram.

  [user@localhost tmp]$ wget https://upload.wikimedia.org/wikipedia/commons/b/b9/Audio_Frequency_tone%2C_Middle_C%2C_C4%2C_261.63hz.ogg -O a.ogg 2> /dev/null
  
  [user@localhost tmp]$ ffmpeg -i a.ogg a.mp3 2> /dev/null
  
  [user@localhost tmp]$ ffmpeg -i a.ogg -af volumedetect tmp.ogg 2>&1 | grep volumedetect
  
  [Parsed_volumedetect_0 @ 0x555f69f3f4a0] n_samples: 88768
  
  [Parsed_volumedetect_0 @ 0x555f69f3f4a0] mean_volume: -3.0 dB
  
  [Parsed_volumedetect_0 @ 0x555f69f3f4a0] max_volume: 0.0 dB
  
  [Parsed_volumedetect_0 @ 0x555f69f3f4a0] histogram_0db: 27541
  
  [user@localhost tmp]$ ffmpeg -i a.mp3 -af volumedetect tmp.mp3 2>&1 | grep volumedetect
  
  [Parsed_volumedetect_0 @ 0x55fd62be4740] n_samples: 88768
  
  [Parsed_volumedetect_0 @ 0x55fd62be4740] mean_volume: -3.4 dB
  
  [Parsed_volumedetect_0 @ 0x55fd62be4740] max_volume: -0.0 dB
  
  [Parsed_volumedetect_0 @ 0x55fd62be4740] histogram_0db: 21340
  
  [user@localhost tmp]$ 

  Why is this bug happening ? Which one should I believe ?

• Power-Up your Matomo installation with Custom Reports

  13 novembre 2017, par InnoCraft — Plugins

  Would you like to create a report in Matomo (Piwik) with just the data you want and nothing else ? Would you like to be free to decide the shape of it ? Are you struggling with the Matomo database and wish you could have an easy interface to create the report you want ? Are you tired of exporting your data in a spreadsheet ? Since last October, there’s a solution and it’s called Custom Reports.

  With custom reports you will :

  1. get a user-friendly interface to create the report you wish
  2. see all the possible combinations to create the report you desire
  3. reveal new data combinations which were not directly available in Matomo (Piwik)

  User friendly interface

  The time when you created your reports from MySQL database is over. Now with custom reports you can create the report you want and get the data you need in just a few seconds.
  Custom reports are part of the main user interface. You can access them in just one click :

  

  As you can see from above the interface is straightforward, just indicate the name of your report and start to select the dimensions and metrics you would like to see.

  See all the possible combinations to create the report you desire

  As a user the big question has always been, how much data does Matomo (Piwik) collect and where can I find a list of all those data points ? Here you have the solution. Matomo is gathering in custom reports all the possible combinations so you can select only the data you want :

  

  Creating such a report is going to take you no more than a minute. As with any reports within Matomo (Piwik), you can easily get information regarding the specific data you are using by hovering your mouse on the question mark next to each dimension and metric :

  

  Make new combinations which were not directly available in Matomo

  By default, not all combinations are possible within the Matomo (Piwik) user interface. Now thanks to Custom Reports, you can easily design the report you want. Here is for example a report crossing page titles and page url :

  

  You can then identify if there are any duplicate titles within your content and see the associated URL in a single report.

  You could also identify easily what are your most viewed entry page from Google :

  

  Custom reports can also be used with segments and filters in order to get even more specific data.
  Here we have an example of a custom report designed to take into consideration only the visits coming from Wikipedia :

  

  What is the next step ?

  As you understood it, Matomo (Piwik) custom reports is the must-have plugin in order to take your Matomo to the next level. Why wait ? Matomo custom reports are available through the marketplace.

  Get Custom Reports

  If you are not sure yet, you can always give it a try within our Matomo Cloud (formerly Piwik Cloud) infrastructure.