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• Anomalie #3697 : Bug svn10000 SPIP 3

  14 février 2016, par MiKaël Navarro

  Cependant je m’étonne que cette erreur là « remplissent les logs du serveur Web », d’autant que l’erreur n’est pas critique.
  Normalement le if ($dir = opendir(...)) n’entre pas dans le if si opendir retourne false. Par contre, oui ça créait une erreur PHP si le dossier n’existait pas, mais qui ne devrait pas perturber il me semble la suite du processus de mise à jour. Je n’ai pas été vérifier cependant.

  Effectivement le if ($dir = opendir(...)) n’entre pas dans le if si opendir retourne false, mais ce n’est pas le code que j’ai dans l’archive spip-3.1.zip (r22707 aujourd’hui en date du 6 janvier), au lieu de ça j’ai seulement (sans le if) :
  

  $dir = opendir($base) ;
  while (($f = readdir($dir)) !== false) 
  ...
  

  De plus je suis d’accord, ce n’est pas une Erreur mais un simple Warning que l’on retrouve dans /var/log/nginx/error.log :
  

  2016/02/14 12:36:04 [error] 1141#0 : *197 FastCGI sent in stderr : "PHP message : PHP Warning :  opendir(baddir/) : failed to open dir : No such file or directory in /home/mickey/public_html/test-opendir.php on line 2
  PHP message : PHP Warning :  readdir() expects parameter 1 to be resource, boolean given in /home/mickey/public_html/test-opendir.php on line 3" while reading response header from upstream, client : 127.0.0.1, server : localhost, request : "GET / mickey/test-opendir.php HTTP/1.1", upstream : "fastcgi ://unix :/var/run/php5-fpm.sock :", host : "localhost" 
  

  
  Ensuite le test while (($f = readdir($dir)) !== false) rentre dans une boucle infinie et c’est avec ça que j’ai créé un log de plus de 2Go !

  D’après les commit, je vois que c’était déjà corrigé dans la version SVN, mais un test supplémentaire mange pas de pain ça sera plus robuste et évitera l’écriture d’un Warning dans les logs pour rien :)

  En tout cas merci pour votre réactivité.

• Simulating MPEG1/2 transmission over a noisy channel [on hold]

  17 novembre 2015, par StepTNT

  The question may sound out of scope here but this is my last resource.

  I need to write a software that does :

  1. Get an uncompressed video from disk
  2. Compress it into MPEG-1 or MPEG-2 being able to change quantization matrix, GOP size and/or macroblock size for DCT/motion search
  3. Apply a repetition code to add redundancy
  4. Simulate transmission over a noisy channel with given error rate
  5. Reconstruct the original stream from the repetition code
  6. Decode the video and compare it with the original one by gathering stats like frame-by-frame difference, file size and stuff like that

  This should by done by a nice GUI to show the input and output videos, alongside their frame difference.

  Given what I need to do, I can write some requirements :

  • An encoder which allows me to change some of the parameters (needed for point 2)
  • A language that allows me to work at bit level (needed for points 3 and 5)
  • A language that allows me to build a nice GUI using a designer (GUI is not the core of the project so I can’t afford wasting time by writing one)

  So far my searches have led to mixed results that are not giving me enough resources to start.

  My first find was this MATLAB project which implements MPEG and has some parameters that can be tweaked (like quantization matrix and GOP pattern for example).
  The problem here is that I don’t know MATLAB at all, so I have no idea on how to link everything and build a GUI.

  So the next step was to move to JAVA, and I found a LOT of FFMPEG wrappers, but none seems to allow me to set the parameters that I need. My last try was with Xuggler but the Wiki is down and the documentation does not talk about what I need. Plus, JAVA doesn’t work at bit level so I’d have issues applying the repetition code.

  Failing with JAVA led me to C# and DirectShowNet, but the documentation is quite lacking and I don’t know how to start because I didn’t find anything related to setting the parameters that I need using Filters.

  The question now is : is there any language/framework/platform that allows me to do what I need without having to deal with pure C/C++ ?
  I’d expect a lot of stuff on this matter since we’re talking about well known codecs, still I’m having a hard time finding what I need.

• Ffmpeg : How to capture audio and metadata simultaneously

  12 janvier 2020, par ChrisDoernen

  I am developing a multi platform app for live audio streaming written in JS. The goal is to get the meters/volumes per channel while capturing audio from the sound card. This has to be done in one command since I get the error device or resource busy when firing multiple commands with the same input.

  Capturing audio works fine using this command :

  ffmpeg -y -f alsa -i hw:CARD=PCH,DEV=0 -ac 2 -b:a 192k -acodec libmp3lame -f mp3 -probesize 64 -rtbufsize 64 -reservoir 0 -fflags +nobuffer -hide_banner pipe:1

  Getting the volume for the right channel works with this command (left channel is analog providing 0.0.1 to -map_channel) :

  ffmpeg -f alsa -i hw:CARD=PCH,DEV=0 -map_channel 0.0.0 -af ebur128=metadata=1,ametadata=print:key=lavfi.r128.M -f null pipe:1

  The question is how to combine these, providing a way to pipe the outputs correctly.

  As a first step, my current approach is to utilize the file argument of ametadata filter (documenation here) and writing to a socket opened with the following JS code

  var net = require('net');
  
  
  
  var server = net.createServer(function (stream) {
  
    stream.on('data', function (c) { console.log('data:', c.toString()); });
  
  });
  
  
  
  server.listen('/tmp/test.sock');

  like

  ffmpeg -f alsa -i hw:CARD=PCH,DEV=0 -map_channel 0.0.1 -af ebur128=metadata=1,ametadata=mode=print:key=lavfi.r128.M:file=unix\:/tmp/test.sock:direct -f null -

  but the socket receives no data and there is no error in ffmpeg.

  Redirecting the output of the streaming command to the socket howerver works :

  ffmpeg -y -f alsa -i hw:CARD=PCH,DEV=0 -ac 2 -b:a 192k -acodec libmp3lame -f mp3 -probesize 64 -rtbufsize 64 -reservoir 0 -fflags +nobuffer -hide_banner unix:/tmp/test.sock

  I am wondering what I am missing and whether I am on the right track alltogether.