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• Trying to capture display output for real-time analysis with OpenCV ; I need help with interfacing with the OS for input

  26 juillet 2024, par mirari

  I want to apply operations from the OpenCV computer vision library, in real time, to video captured from my computer display.
The idea in this particular case is to detect interesting features during gameplay in a popular game and provide the user with an enhanced experience ; but I could think of several other scenarios where one would want to have live access to this data as well. 
At any rate, for the development phase it might be acceptable using canned video, but for the final application performance and responsiveness are obviously critical.

  



  I am trying to do this on Ubuntu 10.10 as of now, and would prefer to use a UNIX-like system, but any options are of interest.
My C skills are very limited, so whenever talking to OpenCV through Python is possible, I try to use that instead.
Please note that I am trying to capture NOT from a camera device, but from a live stream of display output ; and I'm at a loss as to how to take the input. As far as I can tell, CaptureFromCAM works only for camera devices, and it seems to me that the requirement for real-time performance in the end result makes storage in file and reading back through CaptureFromFile a bad option.

  



  The most promising route I have found so far seems to be using ffmpeg with the x11grab option to capture from an X11 display ;
(e.g. the command
ffmpeg -f x11grab -sameq -r 25 -s wxga -i :0.0 out.mpg
captures 1366x768 of display 0 to 'out.mpg').
I imagine it should be possible to treat the output stream from ffmpeg as a file to be read by OpenCV (presumably by using the CaptureFromFile function) maybe by using pipes ; but this is all on a much higher level than I have ever dealt with before and I could really use some directions. 
Do you think this approach is feasible ? And more importantly can you think of a better one ? How would you do it ?

  


• Can I make calls to APIs such as youtube-dl and ffmpeg from a chrome-app ?

  8 janvier 2015, par ErickR

  First of all, I haven’t started the implementation of the system I’m about to describe, as I didn’t want to commit on implementing something I did not know if was possible.

  So, what I’m trying to achieve is to build a chrome-app to download the audio from certain websites (e.g. youtube and soundcloud) using youtube-dl, post process it using ffmpeg and then upload it to a cloud service via some api. The reason I want to do it via a chrome-app is because I could do all the work on the client side (no need for servers) and I’d have the ability to insert javascript into the pages using content scripts, which would make the app pretty simple to use (I could create buttons such as ’download song’ and stuff like that).

  Although I have already read the documentation explaining the NaCl Technical Overview and some of the Application Structure, I still am not sure as to whether I would be able to make these calls via some C/C++ module or if I would get denied due to security reasons.

  To summarize : considering that the user has the needed dependencies in his system (youtube-dl, python, ffmpeg and etc.), is it possible to make calls to third party APIs such as the ones described before via a chrome-app using NaCl ?

  Thank you all in advance,

• lavc : remove libschroedinger encoding and decoding wrappers

  28 mai 2017, par Rostislav Pehlivanov

  lavc : remove libschroedinger encoding and decoding wrappers
  The library has stopped being developed and Debian has removed it
  
  from its repositories citing security issues.
  
  The native Dirac decoder supports everything the library has and basic
  
  encoding support is still provided via the native vc2 (Dirac Pro, intra
  
  only version of Dirac) encoder. Hence, there's no reason to still support
  
  linking to the library and potentially leading users into security issues.
  

  • [DH] Changelog
  • [DH] MAINTAINERS
  • [DH] configure
  • [DH] doc/general.texi
  • [DH] doc/platform.texi
  • [DH] libavcodec/Makefile
  • [DH] libavcodec/allcodecs.c
  • [DH] libavcodec/libschroedinger.c
  • [DH] libavcodec/libschroedinger.h
  • [DH] libavcodec/libschroedingerdec.c
  • [DH] libavcodec/libschroedingerenc.c