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• How do I buffer and capture an RTSP stream to disk based on a trigger ?

  2 septembre 2022, par SJoshi

  I think what I'm asking about is similar to this ffmpeg post about how to capture a lightning strike (https://trac.ffmpeg.org/wiki/Capture/Lightning).

  


  I have a Raspberry Pi with an IP cam over RTSP, and what I'm wondering is how to maintain a continual 5 second live video buffer, until I trigger a "save" command which will pipe that 5 second buffer to disk, and continue streaming the live video to disk until I turn it off.

  


  Essentially, Pi boots up, this magic black box process starts and is saving live video into a fixed-size, 5-second buffer, and then let's say an hour later - I click a button, and it flushes that 5-second buffer to a file on disk and continues to pipe the video to disk, until I click cancel.

  


  In my environment, I'm able to use ffmpeg, gstreamer, or openRTSP. For each of these, I can connect to my RTSP stream and save it to disk, but I'm not sure how to create this ever-present 5 second cache.

  


  I feel like the gstreamer docs are alluding to it here (https://gstreamer.freedesktop.org/documentation/application-development/advanced/buffering.html?gi-language=c), but I guess I'm just not grokking how the buffering fits in with a triggered save. From that article, I get the impression that the end-time of the video is known in advance (I could artificially limit mine, I guess).

  


  I'm not in a great position to post-process the file, so using something like openRTSP, saving a whole bunch of video segments, and then merging them isn't really an option.

  


  Note : After a successful save, I wouldn't need to save another video for a minute or so, so that 5 second cache has plenty of time to fill back up before the next

  


  This is the closest similar question that I've found : https://video.stackexchange.com/questions/18514/ffmpeg-buffered-recording

  


• How to stop ffmpeg when recording the desktop to save the file to the hard disk ?

  27 juin 2022, par Eliot Shein

  I'm trying to record the desktop with the ffmpeg and save a video file to the hard disk.

  


  using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Testings
{
    internal class FFmpeg_Capture
    {
        Process process;

        public FFmpeg_Capture()
        {
            process = new Process();
        }

        public void Start(string FileName, int Framerate)
        {
            process.StartInfo.FileName = @"D:\Captured Videos\ffmpeg.exe"; // Change the directory where ffmpeg.exe is.  
            process.EnableRaisingEvents = false;
            process.StartInfo.WorkingDirectory = @"D:\Captured Videos"; // The output directory  
            process.StartInfo.Arguments = @"-f gdigrab -framerate " + Framerate +
                " -i desktop -preset ultrafast - pix_fmt yuv420p " + FileName;
            process.Start();
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = false;
            Stop();
        }

        public void Stop()
        {
            process.Close();
        }
    }
}


  


  And using it in form1 :

  


  private void btnRecord_Click(object sender, EventArgs e)
        {
            recordToggle = !recordToggle;

            if (recordToggle)
            {
                btnRecord.Text = "Stop";
                record.Start("Testing", 60);
            }
            else
            {
                btnRecord.Text = "Record";
                record.Stop();
            }
        }


  


  but the file Testing never saved to the hard disk. my guess is that

  


  process.Close();


  


  is not like ctrl+ c and ctrl + c is what stopping the ffmpeg and save the file.

  


  This is working but how to remove the black window of the ffmpeg ?

  


  

  


  using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.IO.Pipes;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Testings
{
    internal class FFmpeg_Capture
    {
        Process process;

        public FFmpeg_Capture()
        {
            process = new Process();
        }

        public void Start(string FileName, int Framerate)
        {
            process.StartInfo.FileName = @"D:\Captured Videos\ffmpeg.exe"; // Change the directory where ffmpeg.exe is.  
            process.EnableRaisingEvents = false;
            process.StartInfo.WorkingDirectory = @"D:\Captured Videos\"; // The output directory  
            process.StartInfo.Arguments = @"-y -f gdigrab -framerate " + Framerate +
                " -i desktop -preset ultrafast -pix_fmt yuv420p " + FileName;
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = false;
            process.StartInfo.RedirectStandardInput = true; //Redirect stdin
            process.Start();
        }

        public void Stop()
        {
            byte[] qKey = Encoding.GetEncoding("gbk").GetBytes("q"); //Get encoding of 'q' key
            process.StandardInput.BaseStream.Write(qKey, 0, 1); //Write 'q' key to stdin of FFmpeg sub-processs
            process.StandardInput.BaseStream.Flush(); //Flush stdin (just in case).
            process.Close();
        }
    }
}


  


• How to create a video out of frames without saving it to disk using python ?

  6 septembre 2022, par brenodacosta

  I have a function that returns a frame as result. I wanted to know how to make a video out of a for-loop with this function without saving every frame and then creating the video.

  


  What I have from now is something similar to :

  


  import cv2
out = cv2.VideoWriter('video.mp4',cv2.VideoWriter_fourcc(*'DIVX'), 14.25,(500,258))
for frame in frames:
    img_result = MyImageTreatmentFunction(frame) # returns a numpy array image
    out.write(img_result)
out.release()


  


  Then the video will be created as video.mp4 and I can access it on memory. I'm asking myself if there's a way to have this video in a variable that I can easily convert to bytes later. My purpose for that is to send the video via HTTP post.

  


  I've looked on ffmpeg-python and opencv but I didn't find anything that applies to my case.