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• Create a rolling X second webcam buffer in Linux, press button saves to file

  13 août 2016, par Grant Gibson

  I’m working on a webcam installation with an ’instant replay’ feature. The concept is basically this :

  1. Webcam captures live, 24/7
  2. When user presses a key, the last (previous) 30 seconds of video saves to a file
  3. I’ll then compress that video using something like FFMPEG and upload to a remote server

  I’m fine with step 3 and beyond, but I haven’t been able to find a solution that does the equivalent of a FIFO buffer for video streams [i.e. pretty much what the ’rewind live tv’ buffer on TiVo does].

  Does anyone know of a way to keep a rolling webcam video/audio buffer that can be exported to a file ?

  Design considerations :

  • I’m planning to use a standard webcam, but open to other suggestions
  • Recording would ideally be 1080p, 30fps
  • Recording must include sound
  • Linux hardware and OS can be specified in the answer, there are no existing pre-requisites. Raspberry Pi would be nice if that’s possible, but equally fine with a small Intel machine (e.g. NUC).
  • There’s no requirement to save the 24/7 stream, but it’s ok if that’s a by-product. So, storage permitting it can be saving to a file continuously for say 12 hours and just ’cat’ the last 30 secs to a separate file, if that’s an option ? But better would be the 30 sec rolling FIFO buffer that could potentially do the whole job in RAM.
  • The ’save instant replay’ button will eventually be a physical pushbutton rather than a keyboard key. However, I’ve got that side of things covered (if the solution is RPi I’d use the GPIO pins, if it’s an Intel box I’d probably use an Arduino in HID mode to simulate a keyboard press).

• ffmpeg permission denied though the user has permission

  12 octobre 2014, par codename_subho

  I have installed ffmpeg in my server running ubuntu 14. my flask app project root is at /var/www/project/
  i am able to upload files and my python scripts are able to write new files, but when i run ffmpeg in my script it gives permission denied.
  Also running the below line in terminal

  ffmpeg -i path/to/inputfile /path/to/outputfile & ps aux | grep ffmpeg 
  
  
  
  gives the user running the process is "ubuntu" which has write access to the project folder and its subfolders. As i told you other python script run by user "ubuntu" is able to create file.

  permission denied error happens in both cases(python script and directly in terminal)

  update :
  also looking at the confusion with the permissions, is there a way i can run the app from /home/ubuntu/project instead of /var/www/project. i am using mod_wsgi with apache for my flask-app.

• Révision 98258 : Ne pas casser la liste des sites syndiqués sur une page d’un site avec une pagina...

  8 juin 2016, par kent1@arscenic.info

  Je ne vois pas dans quel cas on souhaiterait ne lister qu’un seul site syndiqué particulier.

  A revert si ne convient pas