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• Algorithm to draw waveform from audio

  27 février 2016, par yayuj

  I’m trying to draw a waveform from a raw audio file. I demuxed/decoded an audio file using FFmpeg and I have those informations : samples buffer, the size of the samples buffer, the duration of the audio file (in seconds), sample rate (44100, 48000, etc), sample size, sample format (uint8, int16, int32, float, double), and the raw audio data itself.

  Digging on the Internet I found this algorithm (more here) :

  White Noise :

  

  The Algorithm

  All you need to do is randomize every sample from –amplitude to
  amplitude. We don’t care about the number of channels in most cases so
  we just fill every sample with a new random number.

  Random rnd = new Random();
  
  short randomValue = 0;
  
  
  
  for (int i = 0; i < numSamples; i++)
  
  {
  
      randomValue = Convert.ToInt16(rnd.Next(-amplitude, amplitude));
  
      data.shortArray[i] = randomValue;
  
  }

  It’s really good but I don’t want to draw that way, but this way :

  

  Is there any algorithm or idea of how I can be drawing using the informations that I have ?

• French CNIL recommends Piwik : the only analytics tool that does not require Cookie Consent

  29 octobre 2014, par Matthieu Aubry — Press Releases

  There has been recent and important changes in France regarding data privacy and the use of cookies. This blog post will introduce you to these changes and explain how you make your website compliant.

  Cookie Consent in the data freedom law

  Since the adoption of the EU Directive 2009/136/EC “Telecom Package”, Internet users must be informed and provide their prior consent to the storage of cookies on their computer. The use of cookies for advertising, analytics and social share buttons require the user’s consent :

  It is necessary to inform users of the presence, purpose and duration of the cookies placed in their browsers, and the means at their disposal to oppose it.

  What is a cookie ?

  Cookies are tracers placed on Internet users’ hard drives by the web hosts of the visited website. They allow the website to identify a single user across multiple visits with a unique identifier. Cookies may be used for various purposes : building up a shopping cart, storing a website’s language settings, or targeting advertising by monitoring the user’s web-browsing.

  Which cookies are exempt from the Cookie Consent rule ?

  France has exempted certain cookies from the cookie consent rule : for those cookies that are strictly necessary to offer the service sought after by the user you do not need to ask consent to user. Examples of such cookies are :

  • the shopping cart cookie,
  • authentication cookies,
  • short lived session cookies,
  • load balancer cookies,
  • certain first party analytics (such as Piwik cookies),
  • persistent cookies for interface personalisation.

  Asking users for consent for Analytics (tracking) Cookies

  For all cookies that are not exempted from the Cookie Consent then you will need to :

  • obtain consent from web users before placing or reading cookies and similar technologies,
  • clearly inform web users of the different purposes for which the cookies and similar technologies will be used,
  • propose a real choice to web users between accepting or refusing cookies and similar technologies.

  You don’t need Cookie Consent with Piwik

  The excellent news is that there is a way to bypass the Cookie Consent banner on your website :

  If you are using another analytics solution other than Piwik then you will need to ask users for consent. If you do not want to ask for consent then download and install Piwik or signup to Piwik Cloud to get started.

  If you are already using Piwik you need to do two simple things : (1) anonymise visitor IP addresses (at least two bytes) and (2) include the opt-out iframe solution in your website (learn more).

  Note that these recommendations currently only apply in France, but because the law is European we can expect similar findings in other European countries.

  CNIL recommends Piwik

  We are proud that the CNIL has identified Piwik as the only tool that respects all privacy requirements set by the European Telecom law.

  

  About the CNIL

  The CNIL is an independent administrative body that operates in accordance with the French data protection legislation. The CNIL has been entrusted with the general duty to inform people of the rights that the data protection legislation allows them.

  The role and responsabilities of the CNIL are :

  • to protect citizens and their data
  • to regulate and control processing of personal data
  • to inspect the security of data processing systems and applications, and impose penalties

  Piwik and Privacy

  At Piwik we love Privacy – our open analytics platform comes with built-in Privacy.

  Future of Privacy at Piwik

  Piwik is already the leader when it comes to respecting user privacy but we plan to continue improving privacy within the open analytics platform. For more information and specific ideas see Privacy enhancing issues in our issue tracker.

  References

  Learn more in these articles in French [fr] or English :

  • [fr] Sites web, cookies et autres traceurs
  • [fr] Comment me mettre en conformité avec la recommandation “Cookies” de la CNIL ?
  • [fr] Recommandation sur les cookies : obligations pour les responsables de sites ?
  • CNIL Starts Controlling Cookie Settings in October 2014
  • CNIL recommends Piwik for compliance with data protection laws

  Contact

  To learn more about Piwik, please visit piwik.org,

  Get in touch with the Piwik team : Contact information,

  For professional support contact Piwik PRO.

• ffmpeg output + issues

  3 octobre 2014, par Ford

  I am trying to get ffmpeg to work using PHP, in its most basic format, just as a test before i develop my code further.

  However i can not get it to work and get no error messages or indications to what is wrong :-(

  i am trying :

  echo exec("/usr/bin/ffmpeg -y -i /home/xxxxxx/public_html/videos/1746/0765916.avi /home/xxxxxx/public_html/videos/1746/test.mp4"); 

  this is creating a 0kb file, but nothing else :-(
  i get no error message (or anything else !)

  (i have error_reporting turned ON and nothing is displayed in browser or server logs)

  if i add the below to get the codecs available :

  echo exec("ffmpeg -formats");

  this just outputs "worse."

  I do not have access to command line, as i am using a shared hosting server.

  I have had the host run the above from command line, and they say it says "codec not found" or words to the effect.

  is there any way i can get any error output into my php file so i can see what is happening.

  Also how do i go about installing codecs, if this is the problem (the host will install them, but have mentioned they have never installed a codec on a Linux box, so would be grateful if i could point them to any install info too)

  Thanks in advance !

  EDIT :

  after adding in the code that @stewe suggests, this is the output when trying to convert to mp4

  (i can convert to to other formats fine )

  FFmpeg version SVN-r0.5.10-4:0.5.10-1, Copyright (c) 2000-2009 Fabrice
  
  Bellard, et al. configuration: --extra-version=4:0.5.10-1
  
  --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libdirac --enable-libgsm --enable-libopenjpeg --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libfaad --enable-libdc1394 --enable-shared --disable-static 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 libavfilter 0. 4. 0 / 0. 4. 0 libswscale 0. 7. 1 / 0. 7. 1 libpostproc 51. 2. 0 / 51. 2. 0 built on
  
  Feb 16 2013 10:07:01, gcc: 4.4.5 Input #0, avi, from
  
  '/home/xxxxx/public_html/videos/1746/0765916.avi':
  
  Duration: 00:01:37.56, start: 0.000000, bitrate: 868 kb/s Stream #0.0:
  
  Video: mpeg4, yuv420p, 480x272 [PAR 1:1 DAR 30:17], 25 tbr, 25 tbn, 25
  
  tbc Stream #0.1: Audio: mp3, 48000 Hz, stereo, s16, 128 kb/s Output
  
  #0, mp4, to '/home/xxxxx/public_html/videos/1746/test.mp4':
  
  Stream #0.0: Video: mpeg4, yuv420p, 480x272 [PAR 1:1 DAR 30:17],
  
  q=2-31, 200 kb/s, 90k tbn, 25 tbc Stream #0.1: Audio: 0x0000, 48000
  
  Hz, stereo, s16, 64 kb/s Stream mapping: Stream #0.0 -> #0.0 Stream
  
  #0.1 -> #0.1 [mpeg4 @ 0x9fb7880]removing common factors from framerate Unsupported codec for output stream #0.1

  If anyone can help as to how to fix this issue, as i would ideally like to convert to mp4