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• avcodec_encode_video2 crash on MinGW32 (but not on MinGW64)

  27 février 2018, par ksb496

  I have been testing for years a software that I am developing, compiled only for 64-bit systems through Qt-MinGW64, without experiencing any kind of issue regarding video encoding (which is one of the features of such application). Recently, I have been attempting to build the corresponding x86 version of my software by compiling it with Qt-MingGW32.

  However, after bulding the same ffmpeg and x264 library versions to create the 32-bit versions and successfully linking them to my project, the application keeps crashing after few frames are encoded, due to segmentation fault error. This is very strange because, as I indicated before, it works flawlessly when compiled for 64-bit systems.

  I have also lost a considerable amount hours trying to combine a big amount of different versions of both ffmpeg and x264 libraries, but with no luck either. Neither it works when disabling threads both for x264 and ffmpeg libraries, hence it does not seem to be a win32 threading issue. Therefore, I have concluded that the error is most likely in my code, which by some chance beyond my comprehension tells ffmpeg to allocate the right amount of memory in the x64 version, but not in the x86 version.

  It must be pointed out also that before the avcodec_encode_video2 call, I do the following calls, among others, in order to allocate the memory associated to the corresponding items (AVFrame, AVCodec, etc.), such as

  avcodec_open2( my_codec_context, my_codec, &opt );
  
  my_av_frame=av_frame_alloc();

  More precisely, the details involving the code structure that I am using can be found here.

  Therefore, the error appears to be more subtle than just issues regarding uninitialized memory.

  Many thanks in advance.

  UPDATE :

  I have discovered the focus of the problem. For some reason, FFmpeg/x264 libraries behave abnormally in Win32 GUI applications compiled with Qt-MinGW32, while they run correctly in Win32 console applications, also compiled with Qt-WinGW32. I have proven this claim performing two dummy tests, in which the exact same piece of code is run through a console application and on a GUI application, succeeding in the first case and failing in the latter one. The code for such tests can be found below, along with the x264 and FFmpeg libraries used in my projects, together with instructions to build them in msys2 with MinGW32 :

  https://takeafile.com/?f=hisusinivi

  I have no idea whether it can be solved by simply tweaking the code or it is a serious bug involving an incompatibility issue. If it is the latter, should it be reported to the Qt/FFmpeg/x264 staff as a major bug ?

• 5 questions you should ask yourself before defining a custom alert in Matomo

  24 janvier 2018, par InnoCraft

  In Matomo, you can create Custom Alerts to automatically be notified of important changes on your website or app. They are a great way to save time, but they also spam your mailbox quickly. Defining good custom alerts takes therefore time and requires some preparations. Here are recommendations on what you should focus on to only get the right alerts at the right time.

  There are several questions you should ask yourself before you define a custom alert :

  1. Do you really want to be alerted ? If the answer is no, then do not use this feature.
  2. What is the level of this alert ? Not important, interesting, highly critical… if it is not highly critical, do not define an alert for this. Probably the emailing report or custom reports feature will be a better fit.
  3. How would you like to be alerted ? SMS, email, sound, homing pigeon (unfortunately we do not support this feature at that time). If you are looking at your emails once a week, then defining a daily email alert won’t make sense.
  4. How would you like the alert to be named ? Give your alert the most explicit name, that’s the first information you will see when you get alerted.
  5. What will be the next step once the alert is triggered ? If you cannot find any action once the alert is triggered, then probably an alert doesn’t make sense.

  Once those questions are answered, you can start configuring custom alerts. There are many alerts you can define but as just mentioned, which alerts you should create always depends on your goals and what is critical to you, or your business. Let’s look at some custom alerts that we see quite often.

  No visit

  One of the easiest custom alert to define. You probably want to be alerted if your website did not receive any visit. As this alert is highly critical, you will want to receive an e-mail, even an SMS. This alert will trigger only if the number of visits is below 1 on a daily basis :

  

  Here the action we will take is to have a look at the website in order to see if it is still live. If the site still works, we will look at the tracking code in order to see if the website is still correctly tracked or not.

  Convinced of this custom alert ? Let’s look at another example.

  Target achieved

  Let’s say you gave a goal to one of your employee to reach a specific threshold in terms of conversions. You can then define a custom alert in order to inform you when the threshold has been reached.

  You can simply do this with an alert saying “Target achieved by Franck” where number of conversions equals the number of actions you defined with him. It takes you only a minute to define something you would have missed otherwise.

  

  Here the actions we can think of are either to congratulate Franck or to ask him what is going wrong if the target is not achieved.

  Did you know that you can also take advantage of Matomo premium features to define custom alerts ? Let’s see one of them.

  Lost SEO ranking

  If you are using the Search Engine Keyword Performance premium feature, there are really interesting combinations you can use to create custom alerts.
  For example, you can be notified when a specific keyword lost or reached a position :

  

  You will be alerted when your website is losing some positions within the search engine results for specific keywords. Here the action we could take is to investigate why we lost a position on Google for this keyword.

  There are many custom alert combinations waiting for you out there. Why not giving them a try ? If you have any questions, feel free to ask them on the Matomo forums.

  The post 5 questions you should ask yourself before defining a custom alert in Matomo appeared first on Analytics Platform - Matomo.

• Convert audio files to mp3 using ffmpeg [closed]

  24 mars, par Hrishikesh -Rishi- Choudhari

  I need to convert audio files to mp3 using ffmpeg.

  



  When I write the command as ffmpeg -i audio.ogg -acodec mp3 newfile.mp3, I get the error :

  



  FFmpeg version 0.5.2, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: 
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 1 / 52.20. 1
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  built on Jun 24 2010 14:56:20, gcc: 4.4.1
Input #0, mp3, from 'ZHRE.mp3':
  Duration: 00:04:12.52, start: 0.000000, bitrate: 208 kb/s
    Stream #0.0: Audio: mp3, 44100 Hz, stereo, s16, 256 kb/s
Output #0, mp3, to 'audio.mp3':
    Stream #0.0: Audio: 0x0000, 44100 Hz, stereo, s16, 64 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
Unsupported codec for output stream #0.0


  



  I also ran this command :

  



   ffmpeg -formats | grep mp3


  



  and got this in response :

  



  FFmpeg version 0.5.2, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: 
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 1 / 52.20. 1
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  built on Jun 24 2010 14:56:20, gcc: 4.4.1
 DE mp3             MPEG audio layer 3
 D A    mp3             MP3 (MPEG audio layer 3)
 D A    mp3adu          ADU (Application Data Unit) MP3 (MPEG audio layer 3)
 D A    mp3on4          MP3onMP4
 text2movsub remove_extra noise mov2textsub mp3decomp mp3comp mjpegadump imxdump h264_mp4toannexb dump_extra


  



  I guess that the mp3 codec isn't installed. Am I on the right track here ?