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• Anomalie #3410 (Nouveau) : Mauvaise formation de requête SQL dans fonction spip_pg_groupby

  16 mars 2015, par Jacques Deguest

  SPIP version 3.0.7

  Résumé :
  Mauvais parsing de requête SQL qui exclue l’alias de table précédent le nom de champs dans GROUP BY tel que :
  SELECT A.id_rubrique AS id_rubrique, R.lang AS lang
  FROM spip_rubriques AS A, spip_rubriques AS R
  WHERE A.id_parent = R.id_rubrique AND A.langue_choisie != ’oui’ AND R.lang<>’’ AND R.lang<>A.lang
  GROUP BY id_rubrique,lang
  ^^{^^^^^^^^^^^}^

  Détail :
  Dans le fichier écrire/req/pg.php à la fonction spip_pg_groupby, la ligne :
  $v = preg_replace(’/^.*\sAS\s+(\w+)\s*$/i’,’\1’, $v) ;
  ne retient que la partie de droite présumant que la partie de gauche est une fonction appliquée par exemple à un champs et qui serait aliasé tel que : SELECT UNE_FONCTION(champs) AS alias_champs, mais ce parsing néglige qu’il puisse s’agir d’un simple aliasing d’un champs existant tel que SELECT A.id_rubrique AS id_rubrique, R.lang AS lang

  Solution suggérée :
  Remplacer la ligne :
  $v = preg_replace(’/^.*\sAS\s+(\w+)\s*$/i’,’\1’, $v) ;
  par :
  if( preg_match( ’/^(\w+\.\w+)\s+AS\s+/i’, $v, $matches ) )
  
  $v = $matches¹ ;
  
  else
  
  $v = preg_replace(’/^.*\sAS\s+(\w+)\s*$/i’,’\1’, $v) ;
  

  Nota bene :
  Faire du parsing de requête SQL est une mavaise idée, car elles peuvent être considérablement compliquée et je ne suis pas sûr que SPIP ait vocation à devenir un parser de requête SQL.
  Le mieux serait peut-être de faire appel à des fonctions qui renverraient la requête SQL écrite de toute pièce à la main et adapté pour le driver SQL utilisé, plutôt que d’utiliser des fonctions qui génèrent du SQL dynamiquement, à moins que cela soit vraiment nécessaire. Cela aurait le mérite de mieux pouvoir optimiser les requêtes SQL par des spécialistes SQL.
  Par exemple, dans le cas ci-dessus, il serait préférable d’avoir une fonction telle que sql_rubrique_lang() et qui renverrait :
  SELECT A.id_rubrique AS id_rubrique, R.lang AS lang
  FROM spip_rubriques AS A, spip_rubriques AS R
  WHERE A.id_parent = R.id_rubrique AND A.langue_choisie != ’oui’ AND R.lang<>’’ AND R.lang<>A.lang
  GROUP BY A.id_rubrique,R.lang

• ffmpeg records 5 frames per second on a device that cheese records at 20 fps

  7 juillet 2017, par David Parks

  Running the following ffmpeg capture on my built in webcam :

  ffmpeg -f v4l2 -framerate 30 -video_size 1920x1080 -i /dev/video0 output.mkv

  I get only 5 fps and see this message :

  The driver changed the time per frame from 1/30 to 1/5

  When I record using cheese I get what looks like 20 fps on that device. And v4l2 seems to claim it can do 30 fps.

  v4l2-ctl --list-formats-ext
  
  ioctl: VIDIOC_ENUM_FMT
  
      Index       : 0
  
      Type        : Video Capture
  
      Pixel Format: 'MJPG' (compressed)
  
      Name        : Motion-JPEG
  
          Size: Discrete 1920x1080
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 1280x720
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 800x600
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 640x480
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 640x360
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 640x480
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 160x120
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 320x240
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 640x480
  
              Interval: Discrete 0.033s (30.000 fps)
  
  
  
      Index       : 1
  
      Type        : Video Capture
  
      Pixel Format: 'YUYV'
  
      Name        : YUYV 4:2:2
  
          Size: Discrete 1920x1080
  
              Interval: Discrete 0.200s (5.000 fps)
  
          Size: Discrete 1280x720
  
              Interval: Discrete 0.100s (10.000 fps)
  
          Size: Discrete 800x600
  
              Interval: Discrete 0.050s (20.000 fps)
  
          Size: Discrete 640x480
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 640x360
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 640x480
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 160x120
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 320x240
  
              Interval: Discrete 0.033s (30.000 fps)
  
          Size: Discrete 640x480
  
              Interval: Discrete 0.033s (30.000 fps)

  When I run ffmpeg :

  Output #0, mjpeg, to 'output.mjpg':
  
    Metadata:
  
      encoder         : Lavf56.40.101
  
      Stream #0:0: Video: mjpeg, yuvj422p(pc), 1920x1080, q=2-31, 200 kb/s, 5 fps, 5 tbn, 5 tbc
  
      Metadata:
  
        encoder         : Lavc56.60.100 mjpeg

  My guess is that it’s recording in raw form from the device and doing the encoding in ffmpeg. If this is correct, how would I get ffmpeg to use the mjpeg native format ?

• FATE Under New Management

  2 août 2010, par Multimedia Mike — FATE Server

  At any given time, I have between 20-30 blog posts in some phase of development. Half of them seem to be contemplations regarding the design and future of my original FATE system and are thus ready for the recycle bin at this point. Mans is a man of considerably fewer words, so I thought I would use a few words to describe the new FATE system that he put together.

  Overview
  Here are the distinguishing features that Mans mentioned in his announcement message :

  • Test specs are part of the ffmpeg repo. They are thus properly versioned, and any developer can update them as needed.
  • Support for inexact tests.
  • Parallel testing on multi-core systems.
  • Anyone registered with FATE can add systems.
  • Client side entirely in POSIX shell script and GNU make.
  • Open source backend and web interface.
  • Client and backend entirely decoupled.
  • Anyone can contribute patches.

  Client
  The FATE build/test client source code is contained in tests/fate.sh in the FFmpeg source tree. The script — as the extension implies — is a shell script. It takes a text file full of shell variables, updates source code, configures, builds, and tests. It’s a considerably minor amount of code, especially compared to my original Python code. Part of this is because most of the testing logic has shifted into FFmpeg itself. The build system knows about all the FATE tests and all of the specs are now maintained in the codebase (thanks to all who spearheaded that effort— I think it was Vitor and Mans).

  The client creates a report file which contains a series of lines to be transported to the server. The first line has some information about the configuration and compiler, plus the overall status of the build/test iteration. The second line contains ’./configure’ information. Each of the remaining lines contain information about an individual FATE test, mostly in Base64 format.

  Server
  The server source code lives at http://git.mansr.com/?p=fateweb. It is written in Perl and plugs into a CGI-capable HTTP server. Authentication between the client and the server operates via SSH/SSL. In stark contrast to the original FATE server, there is no database component on the backend. The new system maintains information in a series of flat files.