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• Why are the red words blurred after opencv and ffmpeg screenshots from a video capture card ? [closed]

  28 août 2024, par yaxin xing

  I tried to take a screenshot after getting the video stream through the video capture card, but the words in red font become blurry after taking the screenshot, but setting the video format to XRGB format in OBS makes it clear. How can I solve this problem in python ?

  


  As you can see in the picture, the red letters are much less clear than the other colors
enter image description here

  


  I tried to capture a frame in ffmpeg and set -pix_fmt but it's still blurry, I tried 4:4:4 color modes like nv12, yuv444, rgb24, etc. but it doesn't work.

  


  I also tried passing ffmpeg's video stream to opencv via pipe, but opencv's recombination of its color channels when converting the video stream caused the colors to change, and didn't solve the problem of the red font not being clear either

  


• Not getting accurate time stamp from FFMPEG after converting datetime to Unix

  13 janvier 2023, par Jacob

  I am creating a video editing application. I have created an ObservableCollection which contains information regarding every frame, 30 per second. I have computed the DateTime per frame as VideoCreationDate + FrameNumber / 29.97. When I display the current time and date with a TextBlock overlaying each frame, the time is perfectly accurate. However, once I convert the date time to Unix time and use it as parameters in the FFMPEG DrawText filter, the time is slightly off. The first few frames are accurate and progressively get worse off the more I scrub through the frames. I am checking the Unix timestamp on each frame and it is correct but for some reason, when I render the FFMPEG command, it converts the timestamp to date time inaccurately.

  


  Below is the method to convert DateTime to Unix :

  


  public long ToUnixTimestamp(DateTime value)
    {
        var dateTimeOffset = new DateTimeOffset(value);
        var unixDateTime = dateTimeOffset.ToUnixTimeSeconds();
        Debug.WriteLine(unixDateTime);
        return unixDateTime;
    }


  


  Below is part of the FFMPEG string containing the DrawText filter :

  


  drawtext=text=\'%{pts\:localtime\:" + ToUnixTimestamp(CurrentFrame.FrameTime) + @"\:'%#I\:%M%p'}\'


  


  I am not sure if I am doing something wrong or if this is a flaw with FFMPEG. Any ideas ?

  


• Revision 00d54aa331 : First pass clean up. One of a series of changes to clean up two pass allocation

  9 mai 2014, par Paul Wilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
  
  First pass clean up.

  One of a series of changes to clean up two pass
  allocation as precursor to support for multiple arf
  or boosted frames per GF/ARF group.

  This change pulls out the calculation of the total bits
  allocated to a GF/ARF group into a function, to aid
  readability and reduce the line count for define_gf_group().

  This change should have no material impact on output.

  Change-Id : I716fba08e26f9ddde3257e7d9b188453791883a3