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• Android and JNI, pipe data to FFmpeg

  2 décembre 2014, par William Seemann

  I’m trying to create a metadata retriever based on FFmpeg. Since raw Android application resources are often only accessible using a file descriptor I need a way to pipe this data to FFmpeg via JNI. I know FFmpeg supports a "pipe" protocol :

  UNIX pipe access protocol.
  
  
  
  Allow to read and write from UNIX pipes.
  
  
  
  The accepted syntax is: 
  
  
  
      pipe:[number]
  
  
  
  number is the number corresponding to the file descriptor of the pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number is not specified, by default the stdout file descriptor will be used for writing, stdin for reading.
  
  
  
  For example: cat test.wav | ffmpeg -i pipe:0

  My question is, how do I programmatically emulate cat test.wav | ffmpeg -i pipe:0 using JNI and avformat_open_input using a FileDescriptor ? Is this possible ?

• Errors when use mps in NVDEC ?

  4 avril 2019, par johnsondeng

  I use ffmpeg compiled with cuda, support nvdec to decode h264 in gpu devices. MPS(https://docs.nvidia.com/deploy/mps/index.html) can share context with different processes, and this can use less gpu storage when use multi-process to decode h264 stream. But when I use ffmpeg in this mode, error got like this.

  Input #0, mpeg, from '/data/yt_traffic/media/nianjianbiao.mp4':
  
  Duration: 00:16:57.97, start: 7833.134000, bitrate: 4219 kb/s
  
  Stream #0:0[0x1e0]: Video: h264 (High), yuv420p(progressive), 1920x1080, 25 fps, 25 tbr, 90k tbn, 50 tbc
  
  File '1.yuv' already exists. Overwrite ? [y/N] y
  
  [AVHWDeviceContext @ 0x4444840] Could not initialize the CUDA driver API
  
  Stream mapping:
  
  Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> rawvideo (native))
  
  Error while opening decoder for input stream #0:0 : Unknown error occurred

  But when mps is shutdown, ffmpeg works fine. Anyone can help ?

• Cannot get MediaStream from Electron app to browser via Openvidu media server

  11 juin 2021, par foxy.bunny

  I'm currently having an issue with openvidu-browser-2.17.0.js

  


  I'm trying to transfer a camera stream from RTSP to an Openvidu media server deployed on cloud and get the stream back on the browser.

  


  The RTSP stream was converted into an HLS stream using FFmpeg and played using hls.js. It was captured in an video tag in HTML and I used the HTMLMediaElement.captureStream().getVideoTrack() to generate MediaStreamTrack and passed it into the videoSource property in initPublisher. This publisher part was wrapped in electron. Then, the stream was connected to our cloud Openvidu server deployed on-premises exactly like in the Docs (https://docs.openvidu.io/en/2.18.0/deployment/deploying-on-premises/). The subscriber part is a simple HTML page displayed on the browser to get the stream from the cloud server. The subscriber is responsible for creating session and generating stream from the media server when streamCreated event occurs.

  


  The whole workflow worked nicely when we tested it with our webcam, however, when we use MediaStreamTrack of our stream video instead of webcam, the subscriber part only showed the blank video.

  


  My question is :

  


  1 : Is it possible to stream an MediaStream to Openvidu media server like that ?

  


  2 : If yes, then what am I doing wrong here ?

  


  Describe the bug

  


  Cannot get MediaStream from Electron app to browser via Openvidu media server.

  


  Expected behavior

  


  Receive the stream from the Electron app to browser via Openvidu media server.

  


  Wrong current behavior

  


  Only get blank video

  


  Client device info

  


  

  • Chrome Version 91.0.4472.77 (Official Build) (64-bit) on Windows 10 Version 10.0.19042 Build 19042