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• YUV raw video color issue

  8 septembre 2021, par adi10289

  I am converting YUV raw video to mp4 using below ffmpeg command but after conversion colors are totally messed up like instead of red its showing blue. Kindly check and confirm if there is any issue with below conversion code.

  



  ffmpeg -f rawvideo -pix_fmt yuv420p -s:v 1920x1080 -r 23.976 -i 2.raw -c:v libx264 output.mp4


  


• Is ffmpeg's chromakey filter broken when matching black/white ?

  7 janvier 2023, par Taylor Brown

  I have a file, colors.png. It looks like this :

  



  Let's say I want to make the red square transparent. When I run ffmpeg -i colors.png -filter_complex "[0]chromakey=0xff0000:similarity=0.1:blend=0.0[out]" -map "[out]" colors-rm-red.png (notice I use similarity=0.1 to make this work), I get exactly that :

  



  How about making the blue square transparent ? ffmpeg -i colors.png -filter_complex "[0]chromakey=0x0000ff:similarity=0.1:blend=0.0[out]" -map "[out]" colors-rm-blue.png works too !

  



  But what about replacing black ? ffmpeg -i colors.png -filter_complex "[0]chromakey=0x000000:similarity=0.1:blend=0.0[out]" -map "[out]" colors-rm-black.png gives me this :

  



  And likewise, replacing white with ffmpeg -i colors.png -filter_complex "[0]chromakey=0xffffff:similarity=0.1:blend=0.0[out]" -map "[out]" colors-rm-white.png gives me the same result :

  



  Why is this ? Even if I use similarity=0.01, which according to the docs "matches only the exact key color", this still doesn't work when I'm trying to make black/white transparent. Is ffmpeg broken, or am I misunderstanding the chromakey filter ?

  


• How to create a video file webm from chunks by media recorder api using ffmpeg

  17 octobre 2020, par Caio Nakai

  I'm trying to create a webm video file from blobs generated by MediaRecorderAPI in a NodeJS server using FFMPEG. I'm able to create the .webm file but it's not playable, I ran this command $ ffmpeg.exe -v error -i lel.webm -f null - >error.log 2>&1 to generate an error log, the error log file contains this :

  


  


  [null @ 000002ce7501de40] Application provided invalid, non monotonically increasing dts to muxer in stream 0 : 1 >= 1

  


  [h264 @ 000002ce74a727c0] Invalid NAL unit size (804 > 74).

  


  [h264 @ 000002ce74a727c0] Error splitting the input into NAL units.

  


  Error while decoding stream #0:0 : Invalid data found when processing input

  


  


  This is my web server code

  


  const app = require("express")();
const http = require("http").createServer(app);
const io = require("socket.io")(http);
const fs = require("fs");
const child_process = require("child_process");

app.get("/", (req, res) => {
  res.sendFile(__dirname + "/index.html");
});

io.on("connection", (socket) => {
  console.log("a user connected");

  const ffmpeg = child_process.spawn("ffmpeg", [
    "-i",
    "-",
    "-vcodec",
    "copy",
    "-f",
    "flv",
    "rtmpUrl.webm",
  ]);

  ffmpeg.on("close", (code, signal) => {
    console.log(
      "FFmpeg child process closed, code " + code + ", signal " + signal
    );
  });

  ffmpeg.stdin.on("error", (e) => {
    console.log("FFmpeg STDIN Error", e);
  });

  ffmpeg.stderr.on("data", (data) => {
    console.log("FFmpeg STDERR:", data.toString());
  });

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

  socket.on("stop", () => {
    console.log("Stop recording..");
    ffmpeg.kill("SIGINT");
  });
});

http.listen(3000, () => {
  console.log("listening on *:3000");
});



  


  And this is my client code, using HTML, JS :

  


  &#xA;&#xA;  &#xA;    &#xA;    &#xA;    &#xA;  &#xA;  <code class="echappe-js">&lt;script src='http://stackoverflow.com/socket.io/socket.io.js'&gt;&lt;/script&gt;&#xA;  &lt;script&gt;&amp;#xA;    const socket = io();&amp;#xA;    let mediaRecorder = null;&amp;#xA;    const startRecording = (someStream) =&gt; {&amp;#xA;      const mediaStream = new MediaStream();&amp;#xA;      const videoTrack = someStream.getVideoTracks()[0];&amp;#xA;      const audioTrack = someStream.getAudioTracks()[0];&amp;#xA;      console.log(&quot;Video trac &quot;, videoTrack);&amp;#xA;      console.log(&quot;audio trac &quot;, audioTrack);&amp;#xA;      mediaStream.addTrack(videoTrack);&amp;#xA;      mediaStream.addTrack(audioTrack);&amp;#xA;&amp;#xA;      const recorderOptions = {&amp;#xA;        mimeType: &quot;video/webm;codecs=h264&quot;,&amp;#xA;        videoBitsPerSecond: 3 * 1024 * 1024,&amp;#xA;      };&amp;#xA;&amp;#xA;      mediaRecorder = new MediaRecorder(mediaStream, recorderOptions);&amp;#xA;      mediaRecorder.start(1000); // 1000 - the number of milliseconds to record into each Blob&amp;#xA;      mediaRecorder.ondataavailable = (event) =&gt; {&amp;#xA;        console.debug(&quot;Got blob data:&quot;, event.data);&amp;#xA;        if (event.data &amp;amp;&amp;amp; event.data.size &gt; 0) {&amp;#xA;          socket.emit(&quot;message&quot;, event.data);&amp;#xA;        }&amp;#xA;      };&amp;#xA;    };&amp;#xA;&amp;#xA;    const getVideoStream = async () =&gt; {&amp;#xA;      try {&amp;#xA;        const stream = await navigator.mediaDevices.getUserMedia({&amp;#xA;          video: true,&amp;#xA;          audio: true,&amp;#xA;        });&amp;#xA;        startRecording(stream);&amp;#xA;        myVideo.srcObject = stream;&amp;#xA;      } catch (e) {&amp;#xA;        console.error(&quot;navigator.getUserMedia error:&quot;, e);&amp;#xA;      }&amp;#xA;    };&amp;#xA;&amp;#xA;    const stopRecording = () =&gt; {&amp;#xA;      mediaRecorder.stop();&amp;#xA;      socket.emit(&quot;stop&quot;);&amp;#xA;    };&amp;#xA;  &lt;/script&gt;&#xA;  &#xA;    
  hello world
  &#xA;
  start rec
  &#xA;
  stop rec
  &#xA;&#xA;    &#xA;    &lt;script&gt;&amp;#xA;      const myVideo = document.getElementById(&quot;myvideo&quot;);&amp;#xA;      myVideo.muted = true;&amp;#xA;    &lt;/script&gt;&#xA;  &#xA;&#xA;&#xA;
  

  


  Any help is appreciated !