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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 !

  


• 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

• Error exporting animation ffmpeg - Matplotlib

  4 décembre 2020, par jonboy

  I'm having issues with exporting an animation using python through anaconda on a Mac. I'm getting the following RuntimeError.

  


  RuntimeError: Requested MovieWriter (ffmpeg) not available


  


  Looking at other questions, the main options are to install ffmpeg via conda :

  


  conda install -c conda-forge ffmpeg


  


  Or designate the path :

  


  plt.rcParams['animation.ffmpeg_path'] = '/usr/local/bin/ffmpeg'


  


  The second option just returns the same RuntimeError. The first option returns a separate error :

  


  BrokenPipeError: [Errno 32] Broken pipe


During handling of the above exception, another exception occurred:

Traceback (most recent call last):

  File "/Users/person/opt/anaconda3/lib/python3.8/site-packages/matplotlib/animation.py", line 1152, in save
writer.grab_frame(**savefig_kwargs)

  File "/Users/person/opt/anaconda3/lib/python3.8/contextlib.py", line 131, in __exit__
self.gen.throw(type, value, traceback)

  File "/Users/person/opt/anaconda3/lib/python3.8/site-packages/matplotlib/animation.py", line 232, in saving
self.finish()

  File "/Users/person/opt/anaconda3/lib/python3.8/site-packages/matplotlib/animation.py", line 368, in finish
self.cleanup()

  File "/Users/person/opt/anaconda3/lib/python3.8/site-packages/matplotlib/animation.py", line 411, in cleanup
raise subprocess.CalledProcessError(

CalledProcessError: Command '['ffmpeg', '-f', 'rawvideo', '-vcodec', 'rawvideo', '-s', '1600x1302', '-pix_fmt', 'rgba', '-r', '10', '-loglevel', 'error', '-i', 'pipe:', '-vcodec', 'h264', '-pix_fmt', 'yuv420p', '-b', '8000k', '-vcodec', 'libx264', '-y', 'test_text.mp4']' died with .


  


  Chasing up this error then refers me back to uninstalling the ffmpeg package. But this just leads to the initial error stating ffmpeg isn't available.