Recherche avancée

Sur d’autres sites (3438)

• Converting timecode to timestamp for ffmpeg

  4 septembre 2020, par Brendon Rathbone

  I am having some issues understanding how timecode could relate to timestamps for grabbing stills or snippets from a video file.

  


  I seem to have two issues. I'm running my code through python as a subprocess if that changes anything.

  


  My code :

  


  '' '

  


  TC = 01:05:08:04
fftc = 01:05:08.125
input = myfile.mp4
InFps = 23.976
tcstamp = 01050804


Command = f'ffmpeg -ss {fftc} -i "{input}" -r {InFps} -frames:v 1 "myfile_{tcstamp}.png"'

P1= subprocess.call(command, shell=True)


  


  '' '

  


  My issues are twofold I think. Since I am trying to adapt timecodes listed in any editor, which reads the timecode track, i get different images(even when correcting for ffmpeg starting from 00:00 compared to my actual timecode). It seems like ffmpeg reads a different duration for my file and thus i can't seem to convert a timecode that would match up in the same place.

  


  I assumed this was simply an issue with h264, but if I try this on a dnxhd file, it can't get a still on a number of frames, giving me the error that the encoded outputfile is empty.

  


  I do notice the metadata on my dnxhd file shows a video track at 23.976 but a timecode track at 24fps.

  


  Is there a way to compare duration to convert timecode to timestamps in my video or is it a limitation I won't be able to overcome ?

  


• Anomalie #3069 (Nouveau) : autorisations

  2 octobre 2013, par chan kalan

  relaté dans le carnet ici http://contrib.spip.net/Autorisations-Dans-Spip
  -> On veut permettre aux administrateurs restreints de modifier le login et mot de passe des visiteurs -> voir la fonction autoriser_auteur_modifier_dist - http://core.spip.org/projects/spip/repository/entry/branches/spip-3-stable/ecrire/inc/autoriser.php#L739 et principalement à cette partie du code ligne 763 :
  

  elseif ($opt[’statut’] == ’0minirezo’ OR $opt[’restreintes’])
                          return false ;
  

  surchargée par :

  elseif ($opt[’statut’] == ’0minirezo’)
                          return false ;

  
  Pourquoi le fait de retirer
  

  OR $opt[’restreintes’]
  

  
  permet-il de modifier le login et mot de passe ?

• How to extract frame types along with motion vectors using extract_mvs.c from ffmpeg

  26 février 2018, par helmo

  I have been researching ways to get frame types (I, P, B) along with the motion vector data returned from extract_mvs.c in the examples folder in ffmpeg.

  The extract_mvs.c file after it is compiled, returns information like this :

  framenum,source,blockw,blockh,srcx,srcy,dstx,dsty,flags
  
  2,-1,16,16,   8,   8,   8,   8,0x0
  
  2, 1,16,16,   8,   8,   8,   8,0x0
  
  2, 1,16,16,  24,   8,  24,   8,0x0
  
  2, 1,16,16,  40,   8,  40,   8,0x0
  
  2, 1,16,16,  56,   8,  56,   8,0x0
  
  2, 1,16,16,  72,   8,  72,   8,0x0
  
  2, 1,16,16,  88,   8,  88,   8,0x0
  
  ...
  
  297, 1,16,16, 248, 280, 248, 280,0x0
  
  297, 1,16,16, 264, 280, 264, 280,0x0
  
  297,-1,16,16, 278, 279, 280, 280,0x0
  
  297, 1,16,16, 280, 280, 280, 280,0x0
  
  297, 1,16,16, 296, 280, 296, 280,0x0
  
  297, 1,16,16, 312, 280, 312, 280,0x0
  
  297, 1,16,16, 328, 280, 328, 280,0x0
  
  297, 1,16,16, 344, 280, 344, 280,0x0

  Along with this information, I would like to output frame type so that I know framenum = 2 is, for example, a ’B’ frame.

  I tried different things, one of which was using a separate command :

  ffprobe input.mp4 -show_frames | grep -E 'pict_type|coded_picture_number'

  But the problem with this command is that it returns data like :

  pict_type=I
  
  coded_picture_number=0
  
  pict_type=B
  
  coded_picture_number=2
  
  pict_type=P
  
  coded_picture_number=1
  
  pict_type=B
  
  coded_picture_number=4
  
  pict_type=P
  
  coded_picture_number=3
  
  ....
  
  pict_type=P
  
  coded_picture_number=293
  
  pict_type=B
  
  coded_picture_number=297
  
  pict_type=B
  
  coded_picture_number=296

  And there is no much I can relate here between coded_picture_number and framenum. The former starts counting from 0 and the later from 2. I assume framenum starting from 2, means the count from this variable is actually from 1, and it ignored 1 in the extraction process as it is maybe an I frame thus no motion vectors.

  So, how can we use only extract_mvs.c to get not only that information it provides but also the frame types in the returned table. Any hints either syntax/command-wise or in editing the c file would be appreciated. Thanks in advance.