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• ffmpeg overwrite v4l2-ctl configuration -> how to do real raw device to network copy ?

  14 décembre 2019, par Serveurperso

  I need to do a real device to a tcp socket copy like :

  cat /dev/video0 | /bin/nc 127.0.0.1 8000 -w 1

  This very basic command line work for my case. I want to do the same, but with the ffmpeg process.
  The aim is to standardize the streaming process, this case, a basic raw copy from a device to network, and advanced transcoding from any source to network, always with the same ffmpeg process.

  I use v4l2-ctl before ffmpeg to make a lot of configuration that I want to keep.

  I tried :

  ffmpeg -loglevel debug -i /dev/video0 -f rawvideo tcp://127.0.0.1:8000
  
  
  
  ffmpeg -loglevel debug -f v4l2 -i /dev/video0 -f rawvideo tcp://127.0.0.1:8000

  The probleme here ffmpeg kill my v4l2 configuration, and I don’t want to setup it twice (v4l2-ctl interface + ffmpeg interface) in my code.

  I also tried :

  ffmpeg -loglevel debug -f rawvideo -i /dev/video0 tcp://127.0.0.1:8000
  
  
  
  ffmpeg -loglevel debug -f rawvideo -i /dev/video0 -f rawvideo tcp://127.0.0.1:8000

  I always get this stderr + exit :

  [IMGUTILS @ 0x7ec1d5f0] Picture size 0x0 is invalid
  
  [AVIOContext @ 0x1e8bb40] Statistics: 26 bytes read, 0 seeks
  
  /dev/video0: Invalid argument

  I also tried the

  -c:v copy

  parameter for all combination above without success :(

  How to do a raw binary copy (like "cat" or "dd" with NetCat) from a device to socket with ffmpeg (without killing v4l2 configuration) ?

  Pascal

• Debugging Gstreamer pipeline with tee and a filesink in C

  28 septembre 2020, par NicolasBourbaki

  There is an excellent example on how to construct a C program using GStreamer and its tee and filesink elements on https://gist.github.com/crearo/a49a8805857f1237c401be14ba6d3b03.
(Another one can be found on https://gstreamer.freedesktop.org/documentation/tutorials/basic/multithreading-and-pad-availability.html?gi-language=c).

  


  The idea of the tee element in a pipeline is similar like the tee program in Unix : Like a T-shaped tube, it allows to add a bifurcation to a pipeline, which is in my case used to display a video stream to the screen (which works perfectly) and writing it at the same time to a file (which doesn't work - the file is created but stays empty, i.e. has a size of 0 bytes after closing the program).

  


  I deviated from the examples mentioned above by neither having a queue element for recording (because I also don't have one for displaying, which works) as well as neither having an encoder nor a muxer. Although this might be a problem for what gets written to the file in the end, I would expect that there is written something to the file at all.

  


  The program does compile. What additional diagnostics could I run in order to pin down the problem ?

  


• View the incoming live mpeg stream from python socket

  19 janvier 2017, par ITried

  So I have an Intel Edison microcontroller running Linux that has a usb cam attached to it. It has a python script that uses ffmpeg to send the mpeg stream to a specific ip:port. I have another ’server’ script on my computer that opens a basic socket and binds on that port. The stream is clearly transferring because when I receive on the server, I print to terminal and all this gibberish and outputs. My question is how can I use ffmpeg or OpenCV (or anything else really) to receive from this port and view it real time ?
  On the Intel Edison, this command transmits data :

  os.system("/home/root/bin/ffmpeg/ffmpeg -s 640x480 -f video4linux2 -i /dev/video0 -f mpeg1video -b 800k -r 30 http://myip:8082")

  On the ’server’ side this the basic socket for binding and receiving.

  s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  
  s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
  
  s.bind(('',8082))
  
  s.listen(1)
  
  conn, addr = s.accept()
  
  print "Connected to:", addr
  
  while True:
  
      data = conn.recv(1024)
  
      if data:
  
          print data

  I want to be able to view the incoming stream live, capture images, or save to video file. I tried looking online, but have not found any for live stream capture through python socket.

  thanks in advance !