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• How do I add a delay to a live stream sourced from webcam (v4l2) with FFMPEG ?

  20 novembre 2018, par David

  How can I use FFMPEG to add a delay to a stream being sent from a (v4l2) webcam to a media server ?

  The use case here is something like a security camera where I want to be able to stream video to a server when something is detected in the video. The easiest way to ensure the event of interest is captured on the video is to use FFMPEG to stream from the camera to a virtual loopback device with an added delay. That loopback device can then be used to initiate live streaming when an even of interest occurs.

  In GStreamer, I would accomplish a delay of this sort with the queue element’s min-threshold-time parameter. For example the following (much-simplified) example pipeline adds a 2 second delay to the output coming from a v4l2 webcam before displaying it :

  gst-launch-1.0 v4l2src device=/dev/video1 ! queue max-size-buffers=0 max-size-time=0 max-size-bytes=0 min-threshold-time=2000000000 ! xvimagesink

  How do I accomplish the same thing with FFMPEG ? There are some technical challenges that prevent us from using GStreamer for this.

  I have investigated the itsoffset option for this, but as far as I can tell it is only usable for already-recorded files, and it is not clear what a good alternative would be.

• What is the Best Approach for Storing and Displaying Video Files as Base64 in HTML for High Performance and Efficiency ? [closed]

  25 août 2023, par Barthez

  I'm currently working on a project where I need to allow users to upload videos, which will then be converted to Base64 and embedded within an HTML file. I'm reaching out to gain a better understanding of the best practices for accomplishing this task while adhering to Stack Overflow guidelines.Here's my plan so far:Video Upload : Users will be able to upload videos through a web interface.Conversion to Base64 : The uploaded video will be converted to Base64 using [specific library/tool].Embedding in HTML : The Base64 encoded video will be embedded within an HTML file using the tag.Before I proceed, I have a few questions:Are there any particular libraries or tools you recommend for converting videos to Base64 efficiently ?What are the potential performance implications of embedding Base64 videos in HTML files, especially considering large video files ?Are there any security concerns I should be aware of when implementing this process ?How can I ensure cross-browser compatibility when embedding these Base64 videos ?Are there any alternatives to this approach that might be more efficient or manageable ?I want to make sure I'm following best practices and avoiding any pitfalls, so any insights, tips would be greatly appreciated. Thank you for your time and assistance !

  


  I attempted to convert an uploaded video to Base64 and embed it within an HTML file.

  


• How to queue ffmpeg FIFO

  29 avril 2013, par Francois

  we build a service similar to youtube. Also converting runs fine with ffmpeg using this script from another post here :

  How do I set up an ffmpeg queue ?

  #!/bin/bash
  
  
  
  pipe=/tmp/ffmpeg
  
  
  
  trap "rm -f $pipe" EXIT
  
  
  
  # creating the FIFO    
  
  [[ -p $pipe ]] || mkfifo $pipe
  
  
  
  while true; do
  
  # can't just use "while read line" if we 
  
  # want this script to continue running.
  
  read line < $pipe
  
  
  
  # now implementing a bit of security,
  
  # feel free to improve it.
  
  # we ensure that the command is a ffmpeg one.
  
  [[ $line =~ ^ffmpeg ]] && bash <<< "$line"
  
  done

  This works pretty good when i send one by one to the named pipe. When i send more than one at same time the second one queues the terminal to the point the first one finished. if a try more than 2 the third one will not be transcoded.

  So i tried to workaround with background sending to get the terminal free (just drop the echo command and close the ssh connection) but this doesn't work, then i played around with screen -X but also no luck. Maybe someone has a good idea to deal this.

  What i wanna do is : Every uploaded video which is needed to transcode will send a echo to the named pipe. FIFO should match but not blocking the terminal. So i think i need something to really queue ffmpeg input.

  kindest regards
  Francois