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• How do I send a mediaStream from the electron renderer process to a background ffmpeg process ?

  26 juillet 2020, par Samamoma_Vadakopa

  Goal (to avoid the XY problem) :

  


  I'm building a small linux desktop application using webRTC, electron, and create-react-app. The application should receive a mediaStream via a webRTC peer connection, display the stream to the user, create a virtual webcam device, and send the stream to the virtual webcam so it can be selected as the input on most major videoconferencing platforms.

  


  Problem :

  


  The individual parts all work : receiving the stream (webRTC), creating the webcam device (v4l2loopback), creating a child process of ffmpeg from within electron, passing the video stream to the ffmpeg process, streaming the video to the virtual device using ffmpeg, and selecting the virtual device and seeing the video stream in a videoconference meeting.

  


  But I'm currently stuck on tying the parts together.
The problem is, the mediaStream object is available inside electron's renderer process (as state in a deeply nested react component, FWIW). As far as I can tell, I can only create a node.js child process of ffmpeg from within electron's main process. That implies that I need to get the mediaStream from the renderer to the main process. To communicate between processes, electron uses an IPC system. Unfortunately, it seems that IPC doesn't support sending a complex object like a video stream.

  


  What I've tried :

  


  


  • starting ffmpeg child process (using child_process.spawn) from within renderer process throws 'fs.fileexistssync' error. Browsing SO indicates that only the main process can start these background processes.

    


  


  • creating separate webRTC connection between renderer and main to re-stream the video. I'm using IPC to facilitate the connection, but offer/answer descriptions aren't reaching the other peer over IPC - my guess is this is due to the same limitations on IPC as before.

    


  


  


  My next step is to create a separate node server on app startup which ingests the incoming RTC stream and rebroadcasts it to the app's renderer process, as well as to a background ffmpeg process.

  


  Before I try that, though, does anyone have suggestions for approaches I should consider ? (this is my first SO question, so any advice on how to improve it is appreciated).

  


• Multiple live video outputs advice. Live stream/Record/Preview, FFMPEG, Windows, Decklink [closed]

  18 septembre 2024, par stroltz

  I am looking for advice on how best to achieve multiple live video outputs.

  


  The live source is a Decklink card on Windows. (We have a ffmpeg build working to access the card) We want 4 outputs ;

  


  


  • We want to run a preview window (low quality would be preferred) just so the user can see the video is working.

    


  


  • We want to be able to live stream - single bit rate, RTMP. (goes up to a CDN)

    


  


  • Independent from the streaming we want to be able to stop and start recording to file. Ideally using CRF. So a separate encode – but maybe we use the RTMP encode, not sure, and do 1 x encode only.

    


  


  • We also want to save a separate audio file. Stops and starts at the same time as the video file above (if required we could do this as a post process on the video file we make above)

    


  


  


  We want to keep CPU use down to as reasonable as possible. (so no high end hardware)

  


  We have had a suggestion of this with ffmpeg ;

  


  Input >> ffmpeg

  


  

  • split input to main and monitoring ;

  


  • scale monitoring stream to lower resolution

  


  • encode both streams

  


  • provide both outputs to local streaming server
ffmpeg >> local streaming server

  


  • use API to start and stop recordings (or web console, if you do it manually)

  


  • provide streams to CDN or/and provide access to your streams for end users

  


  


  recorded files >> another ffmpeg (controlled by some script that get
RECORDING COMPLETED event to start ffmpeg process)

  


  

  • extract audio from recorded file

  


  • save audio into file

  


  


  Which sounds possible, but if doing that, which local streaming server would work best (open source, API...)

  


  or open to other ideas as to the best way.

  


  https://trac.ffmpeg.org/wiki/Creating%20multiple%20outputs shows lots of ways, but I don't think you get to control the individual outputs independently.

  


• lavu/frame : Add Dolby Vision metadata side data type

  3 janvier 2022, par Niklas Haas

  lavu/frame : Add Dolby Vision metadata side data type
  In order to be able to extend this struct later (as the Dolby Vision RPU
  
  evolves), all of the 'container' structs are considered extensible, and
  
  the individual constituent fields must instead be accessed via offsets.
  
  The precedent for this style of access is set in
  
  <libavutil/detection_bbox.h>
  Signed-off-by : Niklas Haas <git@haasn.dev>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] doc/APIchanges
  • [DH] libavutil/dovi_meta.c
  • [DH] libavutil/dovi_meta.h
  • [DH] libavutil/frame.c
  • [DH] libavutil/frame.h
  • [DH] libavutil/version.h