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• Using ffmpeg, the function av_find_input_format("avfoundation") return null

  28 avril 2019, par guojing

  I run this code in iPad mini 4 (Model A1538), iOS 11.2.6

  Try to record audio by FFmpeg.

  av_register_all();
  
  avcodec_register_all();
  
  avdevice_register_all();
  
  
  
  AVFormatContext *pFormatCtx = avformat_alloc_context();
  
  AVDictionary* options = NULL;
  
  av_dict_set(&options,"list_devices","true",0);
  
  AVInputFormat *iformat = av_find_input_format("avfoundation");
  
  printf("==AVFoundation Device Info===\n");
  
  avformat_open_input(&pFormatCtx,"",iformat,&options);
  
  printf("=============================\n");
  
  
  
  if(avformat_open_input(&pFormatCtx,"0",iformat,NULL)!=0){
  
      printf("Couldn't open input stream.\n");
  
      return;
  
  }

  pFormatCtx = NULL, and iformat = NULL.

  Why should this happen, did I missed anything to set ?

• Connect a remote Ip camera as a Webrtc client

  5 avril 2017, par idosh

  I have 2 cameras :

  • An internal webcam embedded in my laptop.
  • A remote IP camera that is connected to my laptop through Wifi (transmits TCP, raw H264 data - no container). I’m getting the stream using node.js.

  My goal is to create a Webrtc network and connect the remote camera as another client.

  I’m trying to figure out possible solutions :

  • My naive thinking was that I would stream the remote camera payload to the browser. But as I came to understand the browser can’t handle the stream without a container. Fair enough. But I don’t understand why it does handle the video stream that arrives from my internal camera (from the navigator.getUserMedia() function). what’s the difference between the two streams ? why can’t I mimic the stream from the remote camera as the input ?
  • To bypass this problem I thought about creating a virtual camera using Manycam (or Manycam like app). To accomplish that I need to convert my TCP stream into an RTP stream (in order to feed Manycam). Though I did saw some info in ffmpeg command line, I couldn’t find info in their node.js api package "fluent-ffmpeg". Is it possible to do it using fluent-ffmpeg ? Or only using the command line tool ? Would it require another rtp server in the middle such as this one ?.
  • Third option I read about is using node.js as a client in Webrtc. I saw it was implemented in "simple-peer". I tried it out using their co-work with socket.io (socket.io-p2p). unfortunately I couldn’t get it to work / : When i’m trying to create a socket/peer in the server - it throws errors, as it expect options that are only available on the client-side (like window, location, etc.). Am I doing something wrong ? maybe there is more suitable framework for this matter ?
  • Forth option is to use a streaming server in the middle such as Kurnto. From my understanding it receives rtp as an input and transmits it as a webrtc client. I feel it’s the most excessive option, but maybe it’s not so bad (I have to admit that I haven’t investigate this option yet).

  any thoughts ?

  thanks !

• FFMPEG - How to wait until all blobs are written before finishing ffmpeg process when getting them from media recorder API

  7 novembre 2020, par Caio Nakai

  I'm using media recorder API to record a video from user's screen and sending the blobs through web socket to a nodejs server. The nodejs server is using the blobs to create a webm video file, the video is being created fine but with a delay, after the user clicks on the stop recording button it stops the media recorder api, however the server didn't finish the processing of all blobs (at least that's what I think it's happening) and then when I check the video file generated the last few seconds of the recording are missing I wonder if there's an way to solve this. Any help is appreciated :)

  


  This is the front-end code that sends the blobs to the nodejs server

  


    const startScreenCapture = async () => {
  try {
    let screenStream;
    videoElem = document.getElementById("myscreen");
    screenStream = await navigator.mediaDevices.getDisplayMedia(
      displayMediaOptions
    );

    const recorderOptions = {
      mimeType: "video/webm;codecs=vp9",
      videoBitsPerSecond: 3 * 1024 * 1024,
    };

    screenMediaRecorder = new MediaRecorder(screenStream, recorderOptions);
    screenMediaRecorder.start(1); // 1000 - the number of milliseconds to record into each Blob
    screenMediaRecorder.ondataavailable = (event) => {
      console.debug("Got blob data:", event.data);
      console.log("Camera stream: ", event.data);
      if (event.data && event.data.size > 0) {
        socket.emit("screen_stream", event.data);
      }
    };

    videoElem.srcObject = screenStream;
    // console.log("Screen stream", screenStream);
    // socket.emit("screen_stream", screenStream);
  } catch (err) {
    console.error("Error: " + err);
  }
};

const stopCapture = (evt) => {
  let tracks = videoElem.srcObject.getTracks();

  tracks.forEach((track) => track.stop());
  videoElem.srcObject = null;
  screenMediaRecorder.stop();
  socket.emit("stop_screen");
  socket.close();
};


  


  This is the nodejs back-end that handle the blobs and generates the videofile

  


    const ffmpeg2 = child_process.spawn("ffmpeg", [
    "-i",
    "-",
    "-c:v",
    "copy",
    "-c:a",
    "copy",
    "screen.webm",
  ]);


  socket.on("screen_stream", (msg) => {
    console.log("Writing screen blob! ");
    ffmpeg2.stdin.write(msg);
  });

  socket.on("stop_screen", () => {
    console.log("Stop recording..");
  });