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• ffmpeg - Copy audio channel but keep the same quality

  30 janvier 2021, par Michele Stieven

  I have a bunch of videos which have been recorded in stereo but the audio is present only on the left channel. I'm using this command to convert them :

  


  find * -prune -name “*.mp4” -exec ffmpeg -n -i “{}” —c:a copy ac 1 “./final/{}” \;


  


  This command seems to lower the files' size, and I'm glad since I don't need a perfect video, having the size so small is fine. However, I need a perfect audio, just the same quality as the original... just in both channels. With this command, the audio quality gets significantly worse. I wouldn't like to mess with options, I'd like to maintain just the exact same audio quality.

  


  The command -c:a copy doesn't seem to work in combination with this command. How can I do it ?

  


  Thanks.

  


  Edit : Here's the report : https://gist.github.com/UserGalileo/49bc8b7b85c05fe29bb044b6f599d71d

  


• How to record a video and create a file every 1 minute and without stopping media recorder as stopping and starting causing delay

  7 janvier 2021, par Karsh Soni

  I want to develop a functionality where i have to start recording or say start continuous recording for more than 5 hours and for every minute i want to create a video file so that i want to store files of a video every minute without any delay or missing any frame.

  


  Right now to create a file i need to stop the media recorder and which leads to stopping and starting media recorder and it ends up losing 1.5 to 3 seconds of delay based on devices where i want to minimize the delay as negligible as possible.

  


  I am getting callbacks or frames for each second but if i would try to save those bitmaps and then try to convert them into video it might work with 5FPS. but with 30 or 60FPS its not performing as continuous frames wouldn't let me write to files efficiently. even though that is being done in background.

  


  Please let me know if you know any alternate solution or any solution that can help me achieve it.

  


• opencv_ffmpeg module crash (IP Camera)

  25 novembre 2016, par Suraksha Ajith

  I’m using IP webcam android app(It converts mobile camera into IP web camera).
  I’m running below code in Visual Studio 2015 with OpenCV 3.1.

  VideoCapture cap; Mat img;
  
  cap.open("http://192.168.0.101:8080/video?x.mjpeg");
  
  while(waitKey(33)!=27)
  
  {
  
      try{
  
          cap>>img;  //code crashes here
  
          if(img.empty())
  
          {
  
           cout<<"camera Closed"<code>

  Getting below error.cIf the internet connection is slow or if the Wi-Fi is disconnected in my android device the program crashes
  Error :

  Exception thrown at 0x0BF2F6F0 (opencv_ffmpeg310.dll) in test.exe :
  0xC0000005 : Access violation reading location 0x00000020.

  If there is a handler for this exception, the program may be safely
  continued.

  even if the code is wrapped within try catch block, it crashes !

  Should I use try {} catch (...) block in source file, if yes, then where should I use this ?
  I referred this link but did not find the right answer.