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• How to stop ffmpeg-lavfi from changing output frame rate per second

  23 mars 2020, par rupinderjeet

  I have an MP4 video from Giphy. This video is 200ms long with 10 fps as reported by mediainfo. I am trying to use ffmpeg to add filters to this video.

  1) Following command works perfectly. The output video keeps fps=10 and duration=200ms

  ffmpeg3 \
  
  -y \
  
  -i input.mp4 \
  
  -i watermark.jpg \
  
  -filter_complex "[0][1]overlay=W-w-20:H-h-20" \
  
  -c:a aac \
  
  -preset ultrafast \
  
  output.mp4

  But, for more filters, I need to use lavfi (for e.g. to place a text-source above or below video, bg color, etc)

  2) Following command with lavfi outputs a video of fps=25 and duration =520ms

  ffmpeg3 \
  
  -y \
  
  -i input.mp4 \
  
  -f lavfi -i color=c=#FFFF0000@1.0:s=1022x682:d=0.5,format=rgba \
  
  -i watermark.jpg \
  
  -filter_complex "[0]scale=1022:682[S3];[S3][2]overlay=W-w-20:H-h-20[O4];[1][O4]overlay=0:0" \
  
  -c:a aac \
  
  -preset ultrafast \
  
  output.mp4

  3) If I add r=10 to lavfi input, fps changes to 10 but duration length is 500ms

  -f lavfi -i color=c=#FFFF0000@1.0:s=1022x682:r=10:d=0.5,format=rgba \

  Even then, the output duration is wrong. And, video just freezes for remaining duration. I can’t use some kind of frame specifier because I do not know input framerate before this command. All video inputs are from user/client of this software I am writing. This is not a one off task.

  This happens only when I use lavfi.

  I want output.mp4 to have same fps and duration as first input(i.e. 0 or input.mp4). How can I do this (preferably in single command) ?

• Stopping rq worker doesn't stop underlying ffmpeg process

  23 mars 2020, par sqr

  I am fairly new to python and rq, and have come to a point I can’t solve by myself.

  I am using ffmpeg-python to encode livestreams, this is distributed in rq workers and displayed on a web app using flask, but since the livestreams can go on forever, I need some way to stop this process while it is still in execution. Opening the terminal where the rq worker is executing the task and pressing ’q’ (ffmpeg shortcut to quit) works, and marks the job as OK, but I need to be able to do this from my web app.

  I have tried getting the worker ID and sending it a SIGKILL, this stops the worker but the task continues running, which is something I don’t understand at all. It’s as if the actual ffmpeg process was being executed somewhere else and stopping the worker didn’t stop ffmpeg. Note that I am not using ffmpeg.run_async, I am using ffmpeg.run which as far as my limited knowledge goes, should not be executed asynchronously. While the streaming is being encoded the worker is marked as busy and has the Job ID properly assigned, so I really don’t understand why, when the worker is killed, the underlying process is still in execution.

  If instead of sending a SIGKILL I send a SIGTERM, the worker says it’s waiting for a warm exit and is never closed, as the ffmpeg process is still doing it’s thing.

  One of my ideas was trying to send a ’q’ keystroke to the worker (which I have no idea how to do even though i’ve been doing some research) or trying to switch from rq to celery, that supposedly supports the cancellation of tasks that are being executed.

  This is my routes file

  @app.route('/streamings', methods=['GET', 'POST'])
  
  @login_required
  
  def streamings():
  
  ...
  
      if form2.submit_stop.data and form2.validate():
  
          conn1 = Redis.from_url('redis://')
  
          queue = rq.Queue('tasks-q', connection=Redis.from_url('redis://'))
  
          workers = rq.Worker.all(queue=queue)
  
  
  
          for worker in workers:
  
              peine = worker.get_current_job_id()
  
              if peine == form2.fld1.data:
  
                  os.kill(worker.pid, signal.SIGKILL)

  and this is my tasks file

  def restream(origin, server, stream_key):
  
      stream_server = generate_url(server, stream_key)
  
      try:
  
          stream_map = None
  
          stream1 = ffmpeg.input(get_manifest(origin), re=None)
  
          stream2 = ffmpeg.input('mosca_66.png')
  
          stream_ol = ffmpeg.overlay(stream1, stream2, x='main_w-overlay_w-50', y='50')
  
          a1 = stream1.audio
  
          stream = ffmpeg.output(stream_ol, a1, stream_server, format='flv', vcodec='libx264', acodec='aac', preset='medium', g='120', crf='23', maxrate='4M', bufsize='5M', channel_layout='stereo')
  
          print(stream.get_args())
  
          ffmpeg.run(stream)
  
      except:
  
          set_complete() 

  Any insight on possible solutions would be greatly appreciated.

  Thanks

• how to stop a function from a button in tkinter

  11 mars 2020, par Cb9867

  I am trying to record audio from microphone in python with the help of ffmpeg.

  By using this i am able to record voice but how can i stop this function by clicking of a button.

  to stop this now i am terminating the IDLE forcefully.

  import os
  
  import subprocess
  
  import tkinter as tk
  
  from tkinter import *
  
  root = Tk()
  
  os.chdir('C://Users/ravir/desktop/')
  
  def recording_voice():
  
    global p
  
    p=subprocess.Popen('ffmpeg -f dshow -i audio="Microphone (2- High Definition Audio Device)" sample.mp3' )
  
  
  
  def stop_rec():  # ho to stop this ???
  
      p.terminate()
  
  
  
  rec_btn = Button(text='Start Recording', width=20, command=recording_voice)
  
  rec_btn.pack()
  
  
  
  stop_btn = Button(text='Stop Recording', width=20, command=stop_rec)
  
  stop_btn.pack()
  
  
  
  root.mainloop()