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• python - record and preview webcam at the same time, using e.g. ffmpeg

  18 décembre 2024, par Jan Oechsler

  I want to record webcam with sound using python. After tryng multiple different methods, ffmpeg with the python wrapper showed the best results.

  


  Recording works, but how can I preview the webcam at the same time, so I know where I am pointing the cam at ?

  


  I've seen this post, but I dont understand how I could implement this in python, using the wrapper.

  


  Any ideas on how to do this ? Or if there is another, easier, solution to record webcam video with sound and preview it simultaneously from within a python (Qt) application ?

  


  This is my code so far :

  


  import ffmpeg
import time

process = (
    ffmpeg
    .input('video=Integrated Camera:audio=Microphone Array (Realtek(R) Audio)', format='dshow')
    .output('out.mp4', pix_fmt='yuv420p')
    .overwrite_output()
    .run_async(pipe_stdin=True, pipe_stderr=True, quiet=True)
)

# This is just to simulate some time-
time.sleep(10)

process.stdin.write('q'.encode())
process.communicate()
process.wait()

print('done')


  


• Flv stream to sockets with ffmpeg, node.js and socket.io

  7 août 2015, par Dan-Levi Tømta

  so i am having some problems with understanding how to pull this off. I know that streaming video is a topic that is hard, and that there is a lot to take account off, but anyway here we go to start of learning how to stream video.

  I am using SocketIoClientDotNet as the node.js client for the c# application.

  I am sending byte arrays of the video to node which are creating a temporary file and appending the buffer to it. I have tried to set the source of the video element to that file but it doesnt read it as video and are all black. I have tried to download a copy of the file since it did not work and it turns out vlc cant play it either. Ok to the code :

  C#

  bool ffWorkerIsWorking = false;
  
  private void btnFFMpeg_Click(object sender, RoutedEventArgs e)
  
  {
  
      BackgroundWorker ffWorker = new BackgroundWorker();
  
      ffWorker.WorkerSupportsCancellation = true;
  
      ffWorker.DoWork += ((ffWorkerObj,ffWorkerEventArgs) =>
  
      {
  
          ffWorkerIsWorking = true;
  
          using (var FFProcess = new Process())
  
          {
  
              var processStartInfo = new ProcessStartInfo
  
              {
  
                  FileName = "ffmpeg.exe",
  
                  RedirectStandardInput = true,
  
                  RedirectStandardOutput = true,
  
                  UseShellExecute = false,
  
                  CreateNoWindow = true,
  
                  Arguments = " -loglevel panic -hide_banner -y -f gdigrab -draw_mouse 1 -i desktop -f flv -"
  
              };
  
              FFProcess.StartInfo = processStartInfo;
  
              FFProcess.Start();
  
              byte[] buffer = new byte[32768];
  
              using (MemoryStream ms = new MemoryStream())
  
              {
  
                  while (!FFProcess.HasExited)
  
                  {
  
                      int read = FFProcess.StandardOutput.BaseStream.Read(buffer, 0, buffer.Length);
  
                      if (read <= 0)
  
                          break;
  
                      ms.Write(buffer, 0, read);
  
                      clientSocket.Emit("video", ms.ToArray());
  
                      ms.Flush();
  
                      if (!ffWorkerIsWorking)
  
                      {
  
                          ffWorker.CancelAsync();
  
                          break;
  
                      }
  
                  }
  
              }
  
          }
  
      });
  
      ffWorker.RunWorkerAsync();
  
  }

  JS (server)

  var buffer = new Buffer(32768);
  
  var isBuffering = false;
  
  var wstream;
  
  socket.on('video', function(data) {
  
      if(!isBuffering){
  
          wstream = fs.createWriteStream('fooTest.flv');
  
          isBuffering = true;
  
      }
  
      buffer = Buffer.concat([buffer, data]);
  
      fs.appendFile('public/fooTest.flv', buffer, function (err) {
  
        if (err) throw err;
  
        console.log('The "data to append" was appended to file!');
  
      });
  
  });

  What am i doing wrong here ?

• ffmpeg—chrome could not load mp4 after server processed

  26 juin 2018, par Yan Ge

  I’m using C# to write the server-side along with ffmpeg to deal with some video files.After I load the video file from client and write the stream to a new file, I couldn’t use ffmpeg to extract some part of the original file, code like below

  string cmd = "-ss " + string.Format("{0:F}", startTime) + " -t " + string.Format("{0:F}", endTime - startTime) + " -i " + filePath + " -vcodec copy -acodec copy " + filePath + " -y";

  it shows the error [mov,mp4,m4a,3gp,3g2,mj2 @ 000002336e7da340] stream 1, offset 0x8fab : partial file ;Invalid data found when processing input

  after investigated, I found that the file which I mentioned as filePath(server side) maybe occupied by windows command(I used the Process to deal with ffmpeg)

  Process myPro = new Process();
  
          myPro.StartInfo.FileName = WebConfigurationManager.AppSettings["FFMPEGPath"];
  
          myPro.StartInfo.UseShellExecute = false;
  
          myPro.StartInfo.RedirectStandardInput = true;
  
          myPro.StartInfo.RedirectStandardOutput = true;
  
          myPro.StartInfo.RedirectStandardError = true;
  
          myPro.StartInfo.CreateNoWindow = true;
  
          myPro.Start();
  
          myPro.StandardInput.AutoFlush = true;
  
          myPro.WaitForExit();
  
          myPro.Close();
  
          myPro.Dispose();
  
          return output;

  I decided to create a new file to perform the extract operation and it works.

  string cmd = "-ss " + string.Format("{0:F}", startTime) + " -t " + string.Format("{0:F}", endTime - startTime) + 
  
  " -i " + filePath + " -vcodec copy -acodec copy " + filePathfull + " -y";

  But when I tried to post back the file name by ajax to client and use video tag in html, it couldn’t load the mp4 file, I think, maybe the mp4 file which generated by ffmpeg is still occupied by system thread, have you ever met such situation ? How could it been fixed ? thanks a lot !