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• How to stream cv2.VideoWriter frames to and RTSP server

  10 juin 2022, par chasez0r

  Environment : Docker, Ubuntu 20.04, OpenCV 3.5.4, FFmpeg 4.2.4

  


  Im currently reading the output of a cv2.VideoCapture session using the CV_FFMPEG backend and successfully writing that back out in real time to a file using cv2.VideoWriter. The reason I am doing this is to drawing bounding boxes on the input and saving it to a new output.

  


  The problem is I am doing this in a headless environment (Docker container). And I’d like to view what's being written to cv2.VideoWriter in realtime.

  


  I know there are ways to pass my display through using XQuartz for example so I could use cv2.imshow. But what I really want to do is write those frames to an RTSP Server. So not only my host can "watch" but also other hosts could watch too.

  


  After the video is released I can easily stream the video to my RTSP Server using this command.

  


  ffmpeg -re -stream_loop -1 -i output.mp4 -c copy -f rtsp rtsp://rtsp_server_host:8554/stream

  


  Is there anyway to pipe the frames as they come in to the above command ? Can cv2.VideoWriter itself write frames to an RTSP Server ?

  


  Any ideas would be much appreciated ! Thank you.

  


• Extract alpha from video ffmpeg android

  24 juin 2018, par Yarik Denisyk

  I want to overlay transparent video on the background image. I have a video where the top half is RGB object and bottom half is an alpha mask.

  

  Now, for making this I do next steps :

  1) I am extracting all frames from video and save to the folder

  2) Each frame splitting to top and bottom half bitmap

  3) Top bitmap composite with bottom mask for extract alpha and get a frame with transparent background

  3) I am drawing each frame on the background and save to a folder

  4) Create a video using FFmpeg

  The problem is step 2, 3 and 4, they very slow. Maybe has another way to overlay transparent video on the background image ?

• When using ffmpeg to compress and create in real time mpeg4 video file from bathc of images getting low quality video how can i improve quality ?

  30 juin 2015, par Brubaker Haim

  The goal here is to create a compressed mp4 video file in real time. I’m saving screenshots as bitmaps type on my hard disk. And i want to create mp4 file and compress the mp4 video file in real time.

  using System;
  
  using System.Windows.Forms;
  
  using System.Collections.Generic;
  
  using System.Linq;
  
  using System.Text;
  
  using System.Threading.Tasks;
  
  using System.Drawing;
  
  using System.IO.Pipes;
  
  using System.Runtime.InteropServices;
  
  using System.Diagnostics;
  
  using System.IO;
  
  using DannyGeneral;
  
  
  
  namespace Youtube_Manager
  
  {
  
      class Ffmpeg
  
      {
  
          NamedPipeServerStream p;
  
          String pipename = "mytestpipe";
  
          System.Diagnostics.Process process;
  
          string ffmpegFileName = "ffmpeg.exe";
  
          string workingDirectory;
  
  
  
          public Ffmpeg()
  
          {
  
              workingDirectory = Path.GetDirectoryName(Application.ExecutablePath);
  
              Logger.Write("workingDirectory: " + workingDirectory);
  
              if (!Directory.Exists(workingDirectory))
  
              {
  
                  Directory.CreateDirectory(workingDirectory);
  
              }
  
              ffmpegFileName = Path.Combine(workingDirectory, ffmpegFileName);
  
              Logger.Write("FfmpegFilename: " + ffmpegFileName);
  
          }
  
  
  
          public void Start(string pathFileName, int BitmapRate)
  
          {
  
              try
  
              {
  
  
  
                  string outPath = pathFileName;
  
                  p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte);
  
  
  
                  ProcessStartInfo psi = new ProcessStartInfo();
  
                  psi.WindowStyle = ProcessWindowStyle.Hidden;
  
                  psi.UseShellExecute = false;
  
                  psi.CreateNoWindow = false;
  
                  psi.FileName = ffmpegFileName;
  
                  psi.WorkingDirectory = workingDirectory;
  
                  psi.Arguments = @"-f rawvideo -vcodec rawvideo -pix_fmt rgb24 -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v mpeg4 -r " + BitmapRate + " " + outPath;
  
                  process = Process.Start(psi);
  
                  process.EnableRaisingEvents = false;
  
                  psi.RedirectStandardError = true;
  
                  p.WaitForConnection();
  
              }
  
              catch (Exception err)
  
              {
  
                  Logger.Write("Exception Error: " + err.ToString());
  
              }
  
          }
  
  
  
          public void PushFrame(Bitmap bmp)
  
          {
  
              try
  
              {
  
                  int length;
  
                  // Lock the bitmap's bits.
  
                  //bmp = new Bitmap(1920, 1080);
  
                  Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
  
                  //Rectangle rect = new Rectangle(0, 0, 1280, 720);
  
                  System.Drawing.Imaging.BitmapData bmpData =
  
                      bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadOnly,
  
                      bmp.PixelFormat);
  
  
  
                  int absStride = Math.Abs(bmpData.Stride);
  
                  // Get the address of the first line.
  
                  IntPtr ptr = bmpData.Scan0;
  
  
  
                  // Declare an array to hold the bytes of the bitmap.
  
                  //length = 3 * bmp.Width * bmp.Height;
  
                  length = absStride * bmpData.Height;
  
                  byte[] rgbValues = new byte[length];
  
  
  
                  //Marshal.Copy(ptr, rgbValues, 0, length);
  
                  int j = bmp.Height - 1;
  
                  for (int i = 0; i < bmp.Height; i++)
  
                  {
  
                      IntPtr pointer = new IntPtr(bmpData.Scan0.ToInt32() + (bmpData.Stride * j));
  
                      System.Runtime.InteropServices.Marshal.Copy(pointer, rgbValues, absStride * (bmp.Height - i - 1), absStride);
  
                      j--;
  
                  }
  
                  p.Write(rgbValues, 0, length);
  
                  bmp.UnlockBits(bmpData);
  
              }
  
              catch(Exception err)
  
              {
  
                  Logger.Write("Error: " + err.ToString());
  
              }
  
  
  
          }
  
  
  
          public void Close()
  
          {
  
              p.Close();
  
          }
  
      }
  
  }

  The Bitmaps images files on my hard disk each one is 1920x1080 and Bit depth 32.

  The video file is on the hard disk at size 1.24MB

  This is a screenshot i took from the video file when playing it.
  You can see how bad the quality is.

  

  This is a link for 10 images of the screenshots i’m using creating from the video file. They are Bitmaps.

  Screenshots rar

  Its something with the arguments :
  This line dosen’t work when i run the program the command prompt window close at once. I can’t even see if there is any erorr/s the command prompt window close too fast.

  psi.Arguments = @"-f libx264 -vcodec libx264 -pix_fmt bgra -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v mpeg4 -r " + BitmapRate + " " + outPath;

  When i’m using this arguments it’s working but making bad quality video :

  psi.Arguments = @"-f rawvideo -pix_fmt bgra -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v mpeg4 -r " + BitmapRate + " " + outPath;