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• How to detetc hardware acceleration in ffmpeg

  19 décembre 2020, par Ali Razmkhah

  I am writing c++ program to screen record by ffmpeg 4.3 ! I need to detect hardware acceleration support such as h264_qsv or h264_nvenc without running ffmpeg.exe !

  


  I explored ffmpeg.exe source code and found no results ! some solutions are deprecated or dose not work on 4.3 !
As instance,

  


  avcodec_find_encoder_by_name("h264_qsv")


  


  returns null even it is exist and works properly !

  


• Capture & save MJPG CCTV stream to file w. FFMPEG

  21 juin 2021, par GBano

  I've been trying to record an IP-cam stream (Foscam, mjpg) via http with ffmpeg.
Can't get the rtsp stream for some reason, but the http/mjpg works fine (VLC IDed it as mjpg).

  


  The stream URL looks like this :
http://192.168.1.123:456/videostream.cgi?user=USERNAME&pwd=PWD

  


  So I created the string (w.o line wrap) :
ffmpeg -i -loglevel debug http://192.168.1.123:456/videostream.cgi?user=USERNAME&pwd=PWD /home/user/Videos/camera.mp4

  


  Some examples I saw are using -c copy and map 0 options as well but I left this out since I defined source and destination clearly and this is just a video, no audio.
segment_time and segment_format I also left out for now (I'd like segments later though- when it's working).

  


  FFMPEG returns : "bash: /home/user/Videos/camera.mp4: No such file or directory"

  


  So I tried a random mjpg stream from the net (Insecam is a nice source for this...) : http://58.69.178.54:80/mjpg/video.mjpg

  


  Leading to :
ffmpeg copy -i -loglevel debug -hide_banner http://58.69.178.54:80/mjpg/video.mjpg /home/user/Videos/camera.mp4

  


  Returns : -loglevel: "No such file or directory" (the same with segment options included, copy excluded).

  


  Shouldn't FFMPEG create the destination file ?

  


  One example mixed FFMPEG with CVLC (Save continuous RTSP stream to 5-10 minute long mp4 files) so I just tried with cvlc.
cvlc http://58.69.178.54:80/mjpg/video.mjpg copy /home/user/Videos/camera.mp4
This opens the stream in a VLC window (despite that I use Cvlc) but does not create a destination file.

  


  I suspect I must have missed something simple & silly, but what ?

  


• ffmpeg break up videos with frame persecond

  25 mai 2018, par jameshwart lopez

  Theres a command to extract images of a video providing frame per seconds

  ffmpeg -i "vide.mp4" -vf fps=1 frames/frame_%04d.png -hide_banner

  Is there a command in ffmpeg to cut video providing fps and save it as video(.mp4 / avi) file like the command above ?

  What i currently have is i created a method to cut the videos with start and endtime but i firstly created a method to get the length of a video so that i could cut the video base on how many frames that was generated by the above command.

   def get_length(self):
  
          """
  
          Gets the length of a video in seconds
  
  
  
          Returns:
  
              float : Length of the video
  
          """
  
  
  
          print("Getting video length: " + self.video_string_path)
  
          command = 'ffprobe -i "'+self.video_string_path+'" -show_entries format=duration -v quiet -of csv="p=0"'
  
          self.command = command
  
          length = str(cmd.execute(command)).strip()
  
          print("lenght: "+length+" second(s)")
  
          return float(length)
  
  
  
  def cut(self, start_time, duration, output_file_name = 'output_file_name.mp4', save_to =''):
  
          """
  
          Cut a video on a specific start time of the video and duration.
  
          Check ffmpeg documentation https://ffmpeg.org/ffmpeg.html for more information about the parameters
  
  
  
          Parameters:
  
              start_time : string
  
                  is the value of ffmpeg -ss with the format: 00:00:00.000
  
  
  
              duration : string | int | float
  
                  is the end point where the video will be cut. Can be the same with start_time format but it could also handle integer as in seconds
  
  
  
              output_file_name : string
  
                  is the file name once the file is save in the hardisk
  
  
  
              save_to : string | optional
  
                  is the directory where the file will be saved
  
  
  
          Returns:
  
              string: file location of the cutted video
  
  
  
          """
  
  
  
          self.make_sure_save_dir_exits(save_to)
  
          print('Cutting ' + self.video_string_path + ' from ' + start_time + ' to ' + str(duration))
  
          print('Please wait...')
  
          file = '"' + self.save_to + output_file_name + '"'
  
          command = 'ffmpeg -i "' + self.video_string_path + '" -ss ' + str(start_time) + ' -t ' + str(duration) + ' -c copy -y ' + file
  
          self.command = command
  
          cmd.execute(command)
  
  
  
          file_loc = self.get_save_to_dir() + output_file_name
  
          print('Done: Output file was saved to "' + file_loc + '"')
  
  
  
          return file_loc + output_file_name