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• Anomalie #3945 (Nouveau) : Notice : Use of undefined constant _SPIP_ECRIRE_SCRIPT - assumed ’_SPIP_...

  6 mai 2017, par Ybbet SPIP

  Bonjour,

  En SPIP 3.2 SVN, en allant sur la page ecrire/ ?exec=admin_plugin&voir=inactif j’ai cette notice :
  

  Notice : Use of undefined constant _SPIP_ECRIRE_SCRIPT - assumed ’_SPIP_ECRIRE_SCRIPT’ in [...]/ecrire/inc/utils.php on line 1889
  

  On utilise dans la fonction generer_url_ecrire() cf. https://core.spip.net/projects/spip/repository/entry/spip/ecrire/inc/utils.php#L1887 la constante _SPIP_ECRIRE_SCRIPT.
  Pourtant cette constante est instanciée dans la fonction spip_initialisation_suite(), précisément ici https://core.spip.net/projects/spip/repository/entry/spip/ecrire/inc/utils.php#L2588

  Il y aurait plusieurs possibilités :
  - Faire un test sur la définition de _SPIP_ECRIRE_SCRIPT et si inexistante, lancer la fonction spip_initialisation_suite() ;
  - Lancer dans la fonction generer_url_ecrire() la fonction spip_initialisation_suite().

• fftools : drop the fake "default" option from ffplay/ffprobe

  9 mars 2022, par Anton Khirnov

  fftools : drop the fake "default" option from ffplay/ffprobe
  It tries to process any unhandled options as AVOptions. Handle this
  
  directly in cmdutils.c, without resorting to a confusing fake option
  
  definition (which is currently visible to the users in -help output).
  

  • [DH] fftools/cmdutils.c
  • [DH] fftools/ffplay.c
  • [DH] fftools/ffprobe.c

• Why are Cb and Cr planes displaced differently from lum by the displace complex filter in ffmpeg ?

  6 mai 2017, par Neb

  I have a video encoded with the yuv420p pixel format and I want to displace its pixels. I’m using ffmpeg and its new displace filter. The filter takes as inputs (the video to be displaced and) two displacement maps respectively for X and Y axis. I decided to create the displacement maps directly into ffmpeg using the nullsrc video source filter and the geq filter to specify the value of the three planes : lum, Cb, Cr. The script is the following :

  ffmpeg INPUT.mp4 -f lavfi -i nullsrc=size=${WIDTH}x${HEIGHT}:d=0.1,geq='lum=128+30*sin(2*PI*X/400):Cb=128+30*sin(2*PI*X/400):Cr='128+30*sin(2*PI*X/400)' -f lavfi -i nullsrc=size=${WIDTH}x${HEIGHT}:d=0.1,geq='lum=128+30*sin(2*PI*X/400):Cb=128+30*sin(2*PI*X/400):Cr=128+30*sin(2*PI*X/400)' -lavfi '[0][1][2]displace' OUTPUT.mp4

  I used the example provided in the documentation of ffmpeg, since the expression used in geq is irrelevant for the purposes of the problem.

  At the and of the computation, I get the pixels of the input video not properly displaced, meaning that I can clearly see a sort of ghost carrying-color-information video under a displaced but b/w one.
  After some tests, I noticed that the displacemnt map created had only the luma plane displaced correctly while the chrominance planes were displaced, but differently from luma, which is the origin of the planes disalignment in the intput video as you can see in the following extract frames :

  Planes separated

  I also noticed that the video describing the Cb and Cr planes of the displacement maps have half resolution of the luma plane.

  My question is : how can i setup correctly the Cr and Cb planes in the geq definition so that they are exactly identical to the luma plane ?

  It would be also great if someone could explain me why ffmpeg gives me an output so much different for luma and Cb, Cr planes even if the function provided is the same.

  If, it can help, i’m using ffmpeg 3.3-static build.

  Thanks for your time.