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• RUN FFMPEG IN PYTHON

  7 janvier 2023, par SMART

  I have 1 video & 1 audio.

  


  video's duration : 4s

  


  audio's duration : 7.48 s

  


  i wrote python function to combine these files

  


  MY CODE :

  


   import subprocess as sp

    def runffmpeg(cmd):
        try:
            pipe = sp.Popen(cmd, stdout=sp.PIPE, stderr=sp.STDOUT,
                            universal_newlines=True)
    
            ffmpeg_output, _ = pipe.communicate()
    
            print(ffmpeg_output)
            return (ffmpeg_output)
    
        except sp.CalledProcessError as err:
            print("FFmpeg stdout output on error:\n" + err.output)
    
    def get_duration(fn):
        cmd = (
            f"ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 {fn}")
    
        cmd1 = (
            f"ffprobe -v error -of flat=s_ -select_streams 1 -show_entries stream=duration -of default=noprint_wrappers=1:nokey=1 {fn}")
        try:
            pipe = sp.Popen(cmd, stdout=sp.PIPE, stderr=sp.STDOUT,
                            universal_newlines=True)
    
            viddur, _ = pipe.communicate()
    
            print(viddur)
    
            pipe = sp.Popen(cmd1, stdout=sp.PIPE, stderr=sp.STDOUT,
                            universal_newlines=True)
    
            auddur, _ = pipe.communicate()
    
            try:
                auddur = float(auddur.strip())
            except:
                auddur = 0
    
            print(auddur)
    
            # if (len(auddur) == 0):
            #     auddur = 0
    
            return float(viddur.strip()), (auddur)
    
        except sp.CalledProcessError as err:
            print("FFmpeg stdout output on error:\n" + err.output)
    

def set_audio_to_video(vn, an, output):

    vdur, adur = get_duration(fn=vn)
    print(f" video duration is  {vdur}")

    auddur, adur = get_duration(fn=an)
    print(f" audio duration is  {auddur}")

   #cmd = (f" ffmpeg -i {vn} -i {an} -filter_complex \"[0:v]setpts=PTS*{auddur}/{vdur}     [v];atempo={auddur}/{vdur} [a]\" -map \"[v]\" -map 1:a -shortest -y {output}")

cmd = (
    f" ffmpeg -i {vn} -i {an} -filter_complex \"[0:v]setpts=PTS*{auddur}/{vdur} [v]\" -map \"[v]\" -map 1:a -shortest -pix_fmt yuv420p -y {output}")
print(cmd)

x = runffmpeg(cmd=cmd)


  


  to call the function :
set_audio_to_video(vn="cremovie.mp4", an="a1.wav", output="output.mp4")

  


  i'm getting error :

  


      Traceback (most recent call last):&#xA;      File "e:\MOVIEPY\FFMPEG-PYTHON.py", line 439, in <module>&#xA;    set_audio_to_video(vn="cremovie.mp4", an="a1.wav", output="output.mp4")&#xA;      File "e:\MOVIEPY\FFMPEG-PYTHON.py", line 424, in set_audio_to_video&#xA;    x = runffmpeg(cmd=cmd)&#xA;  File "e:\MOVIEPY\FFMPEG-PYTHON.py", line 399, in runffmpeg&#xA;    pipe = sp.Popen(cmd, stdout=sp.PIPE, stderr=sp.STDOUT,&#xA;      File "C:\Python39\lib\subprocess.py", line 947, in __init__&#xA;    self._execute_child(args, executable, preexec_fn, close_fds,&#xA;      File "C:\Python39\lib\subprocess.py", line 1416, in _execute_child&#xA;    hp, ht, pid, tid = _winapi.CreateProcess(executable, args,&#xA;    OSError: [WinError 87] The parameter is incorrect&#xA;</module>

  


  final command generated by function will look like :

  


  ffmpeg -i cremovie.mp4 -i a1.wav -filter_complex "[0:v]setpts=PTS*7.489116/4.0 [v]" -map "[v]" -map 1:a -shortest -pix_fmt yuv420p -y output.mp4


  


  i want to extend the video's duration to audio's duration ( video's duration increased to from 4s to 7.48 s)

  


  while running this ffmpeg command in command prompt (CMD) , its working , got no errors but in python , i'm getting errors.

  


  SYSTEM DETAILS :
WINDOWS 10 64 BITS
PYTHON 3.9 64 BITS

  


  WHAT TO DO ?

  


• ffmpeg : video to images with pts in filename

  12 février 2016, par ntg

  I am trying to extract images of exact times (say every second) from a mp4 video of an experiment. There are a lot of methods to do that using ffmpeg out there, but surprisingly enough the time accuracy is off.

  To measure accuracy, I have first time-stamped the video using pts, e.g. :

  -vf "[in] scale=640:-2 , drawtext=fontcolor=white:fontsize=22:fontfile='times.ttf':timecode='22\:10\:55\:00:text='03/12/15__':r=23.976023976:x=0:y=0 [out]"

  And as a result I got a millisecond precision time-stamp on the video. I checked the video and it seems the time-stamps are very accurate. I then tried all the methods I could find out there including :

  -Using -ss [timestamp] to go to an exact time and -vframes 1 to get the first frame at that time : this method is extremely slow since it involves calling ffmpeg once for each second of the video. Furthermore, seems to work fine for the first minutes, but then gets out of sync.

  -Using fps=1 and using out_%05d.jpg as the output. This was probably the most inaccurate, as it went off by whole seconds, plus it never got exactly the 0th millisecond.

  -Using a fast fps, and then selecting only the ones I need, e.g. -vf "fps=10, framestep=10, select=not(mod(n\,40))" was promising for the first minutes, but also became inaccurate after that.

  -I tried writing the pts/date as metadata, but (do not know how to /cannot) write to the metadata of a .jpg from ffmpeg...

  The problem is that after some time, if we are using out_%05d.jpg, the numbers get completely out of sinc, while the -ss gets inaccurate, and takes forever.

  Ideally there should be a way to write the %pts or the date as part of the filename... Does anyone know a method to extract images from an .mp4 file with millisecond precision, preferably using ffmpeg (or its library ? I am using python and getting desperate...)

  [Edit : as explained in the comment by Mulvya, the pts is calculated by using the fps of the video, ffmpeg can give it to you. In my case some of the videos have 30 and others 24*(100/1001) fps. Bellow is an example, which was produced by :

  args = ['ffmpeg',
  
   '-i',
  
   'c:\\Temp\\scr_cam.mp4',
  
   '-y',
  
   '-vf',
  
   "[in] drawtext=fontcolor=black:fontsize=22:fontfile='times.ttf':timecode='17\\:00\\:29\\:00':text='09/02/16__':r=30.0:x=0:y=0, drawtext=fontcolor=black:fontsize=22:fontfile='times.ttf':timecode='00\\:00\\:00\\:00':text='':r=30.0 :x=0:y=30, drawtext=fontcolor=black:fontsize=22:fontfile='times.ttf':text='n\\: %{n}   pts\\:%{pts}':r=30.0:x=0:y=60 [out]",
  
   '-c:a',
  
   'copy',
  
   '-metadata',
  
   'creation_time=2016-02-09T17:00:29',
  
   '-preset',
  
   'ultrafast',
  
   '-threads',
  
   '3',
  
   'c:\\Temp\\stamped_scr_cam.mp4']
  
  subprocess.call(args)

  In it we see that indeed pts = n/30 (n is the frame no). I have tried many combinations of the params of the commands I talk in the beginning, so listing all my efforts would take too much space. As we see, the drawtext seems to be very accurate, so it does not seem to be a problem of incorrect fps.

  

  To get the fps I am using :

  def get_frame_rate_and_duration(filename):
  
      if not os.path.exists(filename):
  
          sys.stderr.write("ERROR: filename %r was not found!" % (filename,))
  
          return -1
  
      args = ["ffprobe",filename,"-v","0","-select_streams","v","-print_format","flat"]
  
      args.extend(["-show_entries","stream=r_frame_rate"])
  
      args.extend(["-show_entries","format=duration"])
  
      out = subprocess.check_output(args).split("\n")
  
      rate = out[0].split('=')[1].strip()[1:-1].split('/')
  
      duration = pd.Timedelta("{0} sec".format(out[1].split('=')[1].strip()[1:-1]))
  
      if len(rate)==1:
  
          rate = float(rate[0])
  
      if len(rate)==2:
  
          rate =  float(rate[0])/float(rate[1])
  
      else:
  
          rate = -1
  
      return rate, duration

• avformat/daudenc : force 2000 sample packet size with a bsf

  3 mars 2024, par Marton Balint

  avformat/daudenc : force 2000 sample packet size with a bsf
  The samples I found all have 2000 sample packets, and by forcing the packet
  
  size with a bsf we could automagically make muxing work for packets containing
  
  more than 3640 samples.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] configure
  • [DH] doc/muxers.texi
  • [DH] libavformat/daudenc.c
  • [DH] tests/ref/fate/dcinema-encode