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• Live video encoding using...?

  27 décembre 2013, par Basic

  I'm attempting to write a fairly simplistic application that will stream video/audio from a webcam to someone else across the internet (ala Skypebut with more control).

  There seems to be very little useful/relevant information on the subjectand what I can find is largely outdated. From my research so far, x264 seems to be the way to go as it offers an ultrafast option which is designed for this situation

  I'm able to turn on the webcam and receive a stream of images. I can also listen on an audio device and get samples.

  Where I'm failing is encoding that information in such a way as to be able to stream with a minimum of latency (from what I've read, 200ms delay is the goal for no obvious lag, including network latency - so let's aim for 100-150ms)

  Things I've tried

  ffmpeg

  This seems to be the most widely used option for encoding. I've had two real issues using it. Firstly, even using x264 with no look-aheads and the bare minimum buffers for stability, the delay seems to be on the order of 700ms using image2pipe. Secondly, it requires ffmpeg to be installed - being able to do this without an external dependency would be nice.

  VLC

  As with ffmpeg this requires an external program which is a negative. Even worse, I can't seem to get a latency of under 2 seconds which seems to increase over time. I've also only been able to get VLC to capture the camera itself rather than take a stream of images which means I don't get a chance to pre-process them.

  DirectShow

  I've seen a number of sites recommending using the windows direct show encoders but I haven't been able to find one that works at anything like real time. In fact, the only one I've managed to get going reliably is a Windows Media codec that has a massive latency and fairly large size.

  Other considerations

  None of the above address the problem of adding an audio stream to the video. I'm not sure if I should attempt to encode them together or send a separate stream alongside the video.

  In short, I've been Googling for a week or so now and haven't found a decent way to do this. Can someone please point me at a decent example/guide ?

• Anomalie #4245 (Fermé) : Petit bug de sous_repertoire()

  11 décembre 2018

  Découvert hier, un enchaînement tueur :

  <span class="CodeRay"><span class="local-variable">$demo</span> = sous_repertoire(_DIR_TMP, <span class="string"><span class="delimiter">'</span><span class="content">demo_</span><span class="delimiter">'</span></span>);
  <span class="comment">// $demo = 'tmp/demo_'</span>
  <span class="local-variable">$bug</span> = sous_repertoire(<span class="local-variable">$demo</span>, <span class="string"><span class="delimiter">'</span><span class="content">potiron</span><span class="delimiter">'</span></span>);
  </span>
  Télécharger

  Le système a rencontré une erreur lors de l’écriture du fichier tmp/demo/potiron/.plat.

  En fait, lors de l’appel de sous_repertoire($base, $subdir), la fonction vire les / et _ finaux de $base (mais pas le _ final éventuel de $subdir).
  Il se retrouve ici à vouloir créer le répertoire tmp/demo/potiron au lieu de tmp/demo_/potiron et n’y arrive pas, vu que le répertoire parent (demo) n’existe pas.

  Histoire¶

  Après quelques fouilles archéologiques, il se trouve que le problème survient probablement avec r8196 qui refactore différemment le code de r6395 :
  - 6395 fil@rezo.n     if (!preg_match(',[/_]$,', $base)) $base .= '/';
  - 8196 esj@rezo.n     if (preg_match(',[/_]$,', $base)) $base = substr($base,0,-1);
  - 16035 fil@rezo.n     $base = rtrim($base, '/_');

  Le tout devait être, je suppose, pour prendre en compte les excentriques répertoires "plats" (dépendants maintenant de la présence de la constante _CREER_DIR_PLAT).

  Corrections¶

  Plusieurs corrections possibles :
  - A) virer la constante _CREER_DIR_PLAT et ses actions, et le rtrim de ce souligné (on est en 2018…).
  - B) simplement appliquer le rtrim du souligné si _CREER_DIR_PLAT est présent (ça corrige pas le bug que $subdir n’aurait alors pas ce rtrim non plus !)
  - C) B + corriger le rtrim pour $subdir de la même manière.

  Je suis partisan de A) sur le trunk, et B) ou C) sur 3.2 et 3.1.

  Des avis ?

• Anomalie #3236 (Nouveau) : opendir et readdir

  27 juin 2014, par Ybbet SPIP

  Hello,

  Juste pour signaler qu’il y a une erreur d’écriture (par conseillé en tout cas) sur :
  - SPIP 3.1 :
  http://core.spip.org/projects/spip/repository/entry/spip/ecrire/public/composer.php#L475
  http://core.spip.org/projects/spip/repository/entry/spip/ecrire/inc/install.php#L348

  - SPIP 3.0 :
  http://core.spip.org/projects/spip/repository/entry/branches/spip-3.0/ecrire/public/composer.php#L392
  http://core.spip.org/projects/spip/repository/entry/branches/spip-3.0/ecrire/inc/install.php#L341

  - SPIP 2.1 :
  http://core.spip.org/projects/spip/repository/entry/branches/spip-2.1/ecrire/public/composer.php#L392
  http://core.spip.org/projects/spip/repository/entry/branches/spip-2.1/ecrire/inc/install.php#L272

  - SPIP 2.0 : http://core.spip.org/projects/spip/repository/entry/branches/spip-2.0/ecrire/public/composer.php#L403

  On a
  

  while ($f = readdir($d))
  

  Au lieu de
  

  while (($f = readdir($d)) !== false)
  

  
  Ecriture adoptée partout ailleurs dans le core de SPIP.