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• mp4 video written with ffmpeg has different first frame based on total number of frames

  26 janvier 2023, par Nitzan Weissman

  I'm trying to read and write videos using ffmpeg, and I got an interesting phenomenon where the first frame is not the same in videos I create that are made from the same frames, only with different lengths.

  


  The commands I'm running to reproduce the problem :

  


  ffmpeg -i .mp4 -frames:v 20 -q:v 3 resource_images/00%04d.png

ffmpeg -hide_banner -loglevel error -framerate 30 -y -i resource_images/00%04d.png  -c:v libx264 -pix_fmt yuv420p -frames:v 20 long_video.mp4 -y

ffmpeg -hide_banner -loglevel error -framerate 30 -y -i resource_images/00%04d.png  -c:v libx264 -pix_fmt yuv420p -frames:v 10 short_video.mp4 -y

ffmpeg -i long_video.mp4 -vf "select=eq(n,0)" -q:v 3 long_frame0.png -y

ffmpeg -i short_video.mp4 -vf "select=eq(n,0)" -q:v 3 short_frame0.png -y


  


  The images long_frame0.png and short_frame0.png are different (I loaded them using Python and compared them, there are many differences).

  


  I find it very peculiar, since I create very short videos, it's those videos first frames, and they are keyframes of those videos (I checked it using ffprobe)

  


  What is the cause of this issue and how do I overcome it to create a consistent first frame for a video, regardless of the video length ?

  


• New Piwik 2.0 public beta for testers

  16 octobre 2013, par matt

  Dear Piwik community,

  We are excited to announce the release of the first public beta version of Piwik 2.0.

  This is software still in development and we really don’t recommend that you run it on a production site — set up a test database just to play with the new version.

  Piwik 2.0 is a major update from Piwik 1.12 and is the result of 5 months of work on the platform !

  What’s changed ?

  We focused on upgrading Piwik source code quality and maintainability : upgraded to PHP 5.3 using namespaces, changed templating library to Twig, started using composer, using Less as well as css, improved QA tests, introduced new Screenshots tests, refactored translations to nice JSON format, refactored LOTS of code, added documentation….

  There also performance improvements, in particular the “All Websites Dashboard” is now usable with 20,000+ websites !

  Several bugs were fixed and we added some very-special-and-exciting new features.

  See the list of closed tickets in Piwik 2.0, or learn more about our recent developments in the Development update blog post.

  Piwik 2 is the open platform for your analytics data !

  How to update to Piwik 2.0 beta ?

  1. You can tell Piwik to use the latest beta from within the user interface. See this FAQ : [piwik.org]
  2. or alternatively you may download the latest beta from the build server, upload these files on top of your existing piwik files, and visit Piwik to upgrade.

  Beta cycle
  The more you test the beta, the more stable our release candidates and our final release will be. If you think you’ve found a bug, you can post it in this forum post. Or, if you’re comfortable writing a reproducible bug report, file one. The stable Piwik 2.0 release is planned for mid-November !

  Happy testing,

  PS : if you are interested in professional support for Piwik, or custom feature development, contact the Piwik experts.

• ffmpeg : Do av_parser_parse work correctly when I feed it with corrupted stream ?

  11 mai 2022, par Suric

  I want to develop a p2p streaming app using ffmpeg over udp so I'm concerning about the feasibility.

  


  So if I can feed av_parser_parse with corrupted stream ?