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• scale intensitiey levels of ffmpeg filter output

  30 septembre 2016, par jlarsch

  how does ffmpeg scale filter output intensities ?
  I have a blend/divide filter that divides 8 bit frames by an 8 bit image and saves the output into an xvid avi.

  blend=all_mode='divide':repeatlast=1

  I would like to understand how exactly ffmpeg maps the filter output (presumably a float ?) to the 8 bit video output levels.

  Does it depend on the intensity histogram of the frame ? (i.e. if 99% of pixels are in the range 0 to 0.5 and 1% of pixels has a much larger intensity e.g. 1)

  Is there a way to specifically provide a lookup table for this mapping at this step ?

• FFMpeg UDP streaming - random split video effect

  3 octobre 2014, par Philmacs

  I’m trying to get a simple local preview of my webcam from an FFMpeg udp stream using an embedded Mplayer window. I can view the live stream using MPlayer but the image is unstable. I’m using the following FFMpeg command :

  ffmpeg -f dshow -video_size 640x480 -i video="Lenovo EasyCamera" -an -f rawvideo -pix_fmt yuyv422 -r 15 udp://127.0.0.1:1234

  And this is the MPlayer command :

  mplayer -demuxer rawvideo -rawvideo fps=15:w=640:h=480:format=yuy2 -nofs -noquiet -identify -idle -slave -nomouseinput -framedrop -wid 1051072

  Sometimes the stream image is OK, but intermittently the image tears randomly and this is how it looks (sorry, not enough rep for images in posts)

  http://imgur.com/sLC3FW0

  I have tried with FFPlay to see if it’s a problem with MPlayer, but I get the same result :

  ffplay -s 640x480 -pix_fmt yuyv422 -f rawvideo -i udp://127.0.0.1:1234

  http://imgur.com/06L42Cj

  This effect is happening at random. If I stop and restart the video might be OK, or it may look like the above. Using aything other than udp and rawvideo adds a delay to the video stream, which I want to avoid.

  The FFMpeg streaming guide suggest methods when you get packet loss, but as far as I’m aware I don’t seem to be getting that.

  I’m new to FFMpeg/Mplayer/video streaming and any help or thoughts greatly appreciated.

• Announcement : Piwik to focus on Reliability, Performance and Security

  7 octobre 2014, par Matthieu Aubry — About, Community

  To our valued team and community,

  Well, we have moved fast and achieved so much during the past few months. Relentlessly releasing major version after major version… We got a lot done including several major new features !

  The speed of adding new features was a great showcase of how agile our small teams and the larger community are. And I’m so proud to see automated testing becoming common practice among everyone hacking on Piwik !

  For the next few months until the new year we will focus on making what we have better. We will fix those rare but longstanding critical bugs, and aim to solve all Major issues and other must-have performance and general improvements. The core team and Piwik PRO will have the vision of making the existing Piwik and all plugins very stable and risk free. This includes edge cases, general bugs but also specific performance issues for high traffic or issues with edge case data payloads.

  We’ll be more pro-active and take Piwik platform to the next level of Performance, Security, Privacy & Reliability ! We will prove to the world that Free/Libre Web software can be of the highest standard of quality. By focusing on quality we will make Piwik even easier to maintain and improve in the future. We are building the best open platform that will let every user liberate their data and keep full control of it.

  If you have any feedback or questions get in touch or let’s continue the discussion in the forum.

  Thank you for your trust and for liberating your data with Piwik,

  Matthieu Aubry
  Piwik founder

  More information

  • How long is each release of Piwik maintained for ? (FAQ)
  • When is the next release of Piwik ? What is the release schedule ? (FAQ)
  • Pulse of Piwik : our monthly pulse report shows 27 different people contributed to Piwik core in the last month !

  

  This is an amazing testament of the power of free/libre software and yet we think this is just the beginning. We hope more developers will join and contribute to the Piwik project !