Recherche avancée

Sur d’autres sites (10201)

• 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

• How to deal with "[asf XX] too long payload" message in ffmpeg ?

  28 mars 2019, par Ayorus

  I am trying to cut a small section of a video using the following sentence :

  ffmpeg.exe -i video.wmv -ss 00:20:02 -to 00:20:09 -crf 22  "C:\test.mp4" -y

  However, ffmpeg hangs showing messages like :

  [asf @ 03327b00] too long payload 0kB time=00:00:00.00 bitrate=N/A speed=   0x
  
         Last message repeated 352 times 
  
  [asf @ 03327b00] too long payload 0kB time=00:00:00.00 bitrate=N/A speed=   0x
  
        Last message repeated 331 times

  I have waited for more than 30 minutes and ffmpeg did not finish the cutting. Does anyone have any idea how to solve this ?

  Any suggestion will be appreciated

  PD. the ffprobe output of the source file is the following :

  ffprobe version N-81831-g97e7f03 Copyright (c) 2007-2016 the FFmpeg developers
  
    built with gcc 5.4.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 32.100 / 55. 32.100
  
    libavcodec     57. 60.101 / 57. 60.101
  
    libavformat    57. 51.102 / 57. 51.102
  
    libavdevice    57.  0.102 / 57.  0.102
  
    libavfilter     6. 63.100 /  6. 63.100
  
    libswscale      4.  1.100 /  4.  1.100
  
    libswresample   2.  2.100 /  2.  2.100
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [asf @ 03b7afe0] too long payload
  
      Last message repeated 159 times
  
  Input #0, asf, from 'F:\video.wmv':
  
    Metadata:
  
      WMFSDKVersion   : 11.0.5721.5145
  
      WMFSDKNeeded    : 0.0.0.0000
  
      IsVBR           : 0
  
      DeviceConformanceTemplate: M
  
    Duration: 01:41:25.95, start: 0.000000, bitrate: 1649 kb/s
  
      Stream #0:0(eng): Video: wmv2 (WMV2 / 0x32564D57), yuv420p, 640x480, 1500 kb/s, 29.97 fps, 29.97 tbr, 1k tbn, 1k tbc
  
      Stream #0:1(eng): Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, 2 channels, fltp, 128 kb/s

• Can FFmpeg crop gif image within 1 second ?

  1er septembre 2021, par jeongbalmountain

  I am developing an iOS application about gif.

  


  But I have a problem with gif cropping. Cropping gif spends so many times with FFmpeg.

  


  Is there a way to reduce the time to crop gif less than 1 second ? (with ffmpeg)