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• Setting up multi webcam streaming

  28 septembre 2013, par Moritz Mädler

  we are currently planning to connect all our offices via webcams selectable from a website. So I guess the setup could be something like this :

  Webcam 1 \
  
  Webcam 2 - > Streamserver -> Webserver displaying html5 Video 
  
  Webcam n /

  I've made first tests from streaming from Windows using VLC to a central ffserver, but the results where rather bad (after 1-2 frames the stream stopped).

  Do you have any suggestions on
   which stream software I can use on the client/webcam site (Linux or Windows)
   which software I can use on the server side (Linux) for collecting and recoding streams ?

  Thanks,

  Moritz

• Issue with openh264enc gstreamer plugin and tcp connections

  20 septembre 2016, par agaldos

  I am trying to stream over TCP encoded video into a EC2 Instance. Using "x264enc" encoder, all works correctly. I get the frames and generate the video correctly.

  The issue comes when I try to use the "openh264enc" encoder.

  If I put in the server "nc -l -p 5555" I can check that data is arriving into the port but when I put the pipeline goes to PREROLLING state and nothing more happens. If I cut the process in the sender, this message appears in the server :

  ubuntu@ip-172-31-87-56:~$ gst-launch-1.0 -e -v tcpserversrc host=ec2-52-29-128-23.eu-central-1.compute.amazonaws.com port=5555 ! h264parse ! mpegtsmux ! filesink location=file.ts
  
  Setting pipeline to PAUSED ...
  
  /GstPipeline:pipeline0/GstTCPServerSrc:tcpserversrc0: current-port = 5555
  
  Pipeline is PREROLLING ...
  
  ERROR: from element /GstPipeline:pipeline0/GstH264Parse:h264parse0: No valid frames found before end of stream
  
  Additional debug info:
  
  gstbaseparse.c(1281): gst_base_parse_sink_event_default (): /GstPipeline:pipeline0/GstH264Parse:h264parse0  
  
  ERROR: pipeline doesn't want to preroll.
  
  Setting pipeline to NULL ...
  
  /GstPipeline:pipeline0/GstTCPServerSrc:tcpserversrc0: current-port = 0
  
  Freeing pipeline ...

  Pipeline used in the EC2 Instance, the server :

  gst-launch-1.0 -e -v tcpserversrc host=ec2-52-29-128-23.eu-central-1.compute.amazonaws.com port=5555 ! h264parse ! mpegtsmux ! filesink location=file.ts

  Sender pipeline with x264enc :

  gst-launch-1.0 -e videotestsrc horizontal-speed=5 ! x264enc ! tcpclientsink port=5555 host=52.29.128.23

  Sender pipeline with openh264enc :

  gst-launch-1.0 -e videotestsrc horizontal-speed=5 ! openh264enc ! tcpclientsink port=5555 host=52.29.128.23

• Can FFMPEG be used to change the transparency of a single PNG ?

  19 juillet 2020, par Chameleon

  I know that FFMPEG can manipulate transparency using fade in/fade out over a series of frames. I just haven't found a way to generate a png with a specified transparency setting.

  


  I am in the process of creating a lot (20 in first set) of procedurally-generated videos. Each video requires several starts and stops, where with each stop, a png overlay describing what is seen will be displayed for several (actual number TBD, and may vary) frames. I'd like each overlay to fade in over x frames, display for y frames at full opacity and then fade out over y frames. The documentation on FFMPEG really sucks at explaining fade effects, and no one I've found showing usage actually explains what all of the parameters do.

  


  The original sources for the videos are CGI png frames with a transparent background. I will be making the descriptive overlays with transparent backgrounds (same resolution as the CGI frames) - I'm really hoping to not have to manually save each overlay (8 overlays per video at a minimum) with 4 to 6 (or more) transparency settings - The company is being real indecisive as to the length of the fade in/out or the "hang time" of the descriptive overlays.

  


  I have already created a Python script that uses FFMPEG to place overlays on specific frames, then uses FFMPEG to stitch all frames into a single video, adds a background to the video and then places the company's watermark on the video. It already manages the key frames and what images should be overlaid (and for how many frames). It is working well, but the company doesn't like the lack of fade. I already have the framework in place to manage the fade in/out duration (I'm just missing the answer to this question). I created the script because I have no doubt that I'll have to generate the final output on the first couple of videos a number of times to appease the stakeholders.

  


  I'm really hoping to find a fairly easy way to hand FFMPEG a png with a transparent background and have FFMPEG hand me a copy of the image whose non-transparent part is now "x percent" transparent (or "y percent" opaque). I know from failed attempts that FFMPEG doesn't choke trying to make a region more than 100% transparent.

  


  It's a real pain to get approval to install new software on the workstation, so I'm not actually interested in any suggestion that doesn't use FFMPEG or a pretty vanilla Python installation. - It's not that the other software might not be useful, it just means that if other software is needed, I'll have to manually create the frames.