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• High Quality Screen Capture with FFmpeg

  18 novembre 2015, par plumzl

  I’m trying to figure out a command for high quality screen capture on REHL.

  I have tried various options, but none really worked. The quality is not good enough. I’m quite new to ffmpeg and doesn’t quite understand all the different flags. So any help would be appreciated !

  The commands I have tried :

  ffmpeg -y -f x11grab -r 30 -s 1920x1080 -i :0.0+0,0 -vcodec libx264 -strict -2 -b:v 16M output.mov

  The first command I tried. The weird thing is it doesn’t seem to preserve the bitrate specified -b:v 16M. The output video’s bitrate is only 2mb/s. Is that not the correct way to specify bitrate when doing screen capture ?

  ffmpeg -f x11grab -s 1920x1080 -r 30 -i :0.0 -qscale 0 -vcodec huffyuv output.mov

  The huffyuv codec is supposed to be lossless, but the quality doesn’t seem to be any better than the libx264 output.

  ffmpeg -f x11grab -r 30 -s 1920x1080 -i :0.0+0,0 -vcodec copy -pix_fmt yuv420p -qscale 0 -an output.mkv
  
  ffmpeg -f rawvideo -pix_fmt yuv420p -s:v 1920x1080 -r 30 -i output.mkv -an -c:v libx264 -qscale 0 result.mov 

  I’m even trying to capture rawvideo and then convert it to libx264 codec viedeo. But the output is corrupted.

  I’m using the version of ffmpeg that’s built on April 23rd this year. It doesn’t have the preset like -vpre lossless_ultrafast which I see mentioned in a lot posts.

  Edit :

  After more research, this is the command I end up using. I have to use h264 codec and yuv420p as pixel_fmt since I need to be able to play the quicktimes using quicktime.

  ffmpeg -y -f x11grab -framerate 30 -video_size 1920x1080 -i :0.0+0,0 -c:v libx264 -pix_fmt yuv420p -qp 0 -preset ultrafast output.mov

  The quality doesn’t seem to be much improved even though -qp is set to 0. But it could also because of the rgb conversion to yuv color space according to this post.

  https://trac.ffmpeg.org/wiki/Encode/H.264

• Help us Reset The Net today on June 5th

  5 juin 2014, par Piwik Core Team — Community, Meta

  This blog post explains why the Piwik project is joining ResetTheNet online protest and how you can help make a difference against mass surveillance. It also includes an infographic and links to useful resources which may be of interest to you.

  Snowden revelations, a year ago today

  On June 5, 2013 the Guardian newspaper published the first of Edward Snowden’s astounding revelations. It was the first of a continuous stream of stories that pointed out what we’ve suspected for a long time : that the world’s digital communications are being continuously spied upon by nation states with precious little oversight.

  Unfortunately, mass surveillance is affecting the internet heavily. The Internet is a powerful force that can promote democracy, innovation, and creativity, but it’s being subverted as a tool for government spying. That is why Piwik has decided to join Reset The Net.

  June 5, 2014 marks a new year : a year that will not just be about listening to the inside story of mass surveillance, but a new year of fighting back !

  How do I protect myself and others ?

  Reset the Net is asking everyone to help by installing free software tools that are designed to protect your privacy on a computer or a mobile device.

  Reset the Net is also calling on websites and developers to add surveillance resistant features such as HTTPS and forward secrecy.

  Participate in ResetTheNet online protest

  Have you got your own website, blog or tumblr ? Maybe you can show the Internet Defense League’s “Cat Signal !” on your website.Get the code now to run the Reset the Net splash screen or banner to help make privacy viral on June 5th.

  Message from Edward Snowden

  Evan from FFTF sent us this message from Edward Snowden and we thought we would share it with you :

  One year ago, we learned that the internet is under surveillance, and our activities are being monitored to create permanent records of our private lives — no matter how innocent or ordinary those lives might be.

  Today, we can begin the work of effectively shutting down the collection of our online communications, even if the US Congress fails to do the same. That’s why I’m asking you to join me on June 5th for Reset the Net, when people and companies all over the world will come together to implement the technological solutions that can put an end to the mass surveillance programs of any government. This is the beginning of a moment where we the people begin to protect our universal human rights with the laws of nature rather than the laws of nations.

  We have the technology, and adopting encryption is the first effective step that everyone can take to end mass surveillance. That’s why I am excited for Reset the Net — it will mark the moment when we turn political expression into practical action, and protect ourselves on a large scale.

  Join us on June 5th, and don’t ask for your privacy. Take it back.

  – Message by Edward Snowden

  ResetTheNet privacy pack infographic

  

  Additional Resources

  Configure Piwik for Security and Privacy

  • Turn on automatic SSL redirection in your Piwik.
  • Configure Piwik for advanced Privacy.
  • Best security practises for Piwik.

  More info

  • Learn why this matters (EFF)
  • Data Privacy Day – Why is privacy important ? (Piwik)
  • Web Analytics Privacy (Piwik)

• Révision 24498 : Exclure les fichier CACHEDIR.TAG de la vidange de cache

  6 février 2020, par bruno@eliaz.fr

  Ref #4431 & https://www.mail-archive.com/spip-zone@rezo.net/msg49159.html