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• Image generated by System.Drawing.Image is 10x larger than original file

  13 mai 2021, par Ninbura

  I've written a Powershell script that extracts one frame from a dshow capture device using FFmpeg, and then copies the output image from a file to my clipboard :

  


  $screenshot = [System.Drawing.Image]::FromFile((Get-Item -Path $outputFilePath))
[System.Windows.Forms.Clipboard]::SetImage($screenshot)
$screenshot.Dispose()


  


  The original file is a 1MB JPEG, but the image in my clipboard is an 11MB PNG. When I go to paste this file into something like Discord the file size is too large, unless you have Discord Nitro.

  


  Is there any way to avoid this file size inflation while using [System.Drawing.Image]::FromFile() ?

  


  Here's an easy test template :

  


  Add-Type -AssemblyName System.Drawing
Add-Type -AssemblyName System.Windows.Forms

$screenshot = [System.Drawing.Image]::FromFile((Get-Item -Path "Path to picture"))
[System.Windows.Forms.Clipboard]::SetImage($screenshot)
$screenshot.Dispose()


  


  Edit 2021/05/13 :

  


  Interestingly, it's starting to seem like this is a limitation of copying an image to a clipboard. I decided to dig deeper and see if the image size was increasing when I drew the image with System.Drawing.Image or when I pushed it in my clipboard with System.Windwos.Forms.Clipboard. If I save the image before putting it my clipboard like so, it retains the original file size, even if I change the extension to png :

  


  Add-Type -AssemblyName System.Drawing
Add-Type -AssemblyName System.Windows.Forms

$screenshot = [System.Drawing.Image]::FromFile((Get-Item -Path "C:\Users\gabri\Pictures\FFScreenshots\2021-05-12 19-04-26.845.jpeg"))
$screenshot.Save("C:\Users\gabri\Pictures\FFScreenshots\test.jpeg") # test.png makes no difference
$screenshot.Dispose()


  


  So it would seem that the image grows exponentially in size specifically when I push it to my clipboard. I verified this by simply uploading an image to Discord, copying it to my clipboard (click image > Open original > right click and copy result), and uploading it again. Sure enough, the new image pasted from my clipboard was around 10x the size of the original image (1MB vs 12MB). I wondered if this was a "limitation" of Windows so I ran the same test on Ubuntu 20.04. Uploaded an image to Discord, copied the image to my clipboard, and uploaded it again. Once again the image was about 10x larger, though slightly smaller than then when I uploaded the image from my clipboard on my Windows machine (11.4MB VS 12MB). Just to make sure this wasn't limited to Discord, I ran the same test with Gmail in-browser on both operating systems, same result.

  


  Alas, there appears to be something happening when you copy an image to a clipboard that drastically increases file size. One thing's for sure, whatever's happening is definitely over my head.

  


• ffmpeg options to stream to Youtube

  24 octobre 2022, par David Goncalves

  Please bear with me as I don't really understand most of the commands behind ffmpeg.

  


  I am using this code to live stream from a raspberry 4B with a USB Logitech C920 to YouTube :
ffmpeg -re -f s16le -i /dev/zero -f v4l2 -thread_queue_size 512 -codec:v h264 -s 1920x1080 -i /dev/video0 -codec:v copy -acodec aac -b:v 128k -g 60 -f flv rtmp ://a.rtmp.youtube.com/live2/[key]

  


  The streaming works but I get the following error in the command line :
Non-monotonous DTS in output stream 0:0 ; previous : 0, current : -167 ; changing to 0. This may result in incorrect timestamps in the output file.

  


  I also get this error in Youtube studio :
Please use a keyframe frequency of four seconds or less. Currently, keyframes are not being sent often enough, which can cause buffering. The current keyframe frequency is 8.0 seconds. Note that ingestion errors can cause incorrect GOP (group of pictures) sizes.
Any help ?

  


• Anomalie #4293 (Nouveau) : Nettoyage de tmp/upload

  20 février 2019

  Un truc qui m’arrive régulièrement : en faisant un peu de maintenance sur un site, je vois que tmp/upload contient 30 Go de vieux docs datant de 2014 à aujourd’hui.
  30 Go stockés pour rien depuis des années, dupliqués et redupliqués sur des serveurs de backups...

  J’envoie un mail au webmaster, en lui précisant qu’il peut supprimer sans risque les fichiers de tmp/upload une fois qu’il les as attachés à un article.
  Sa réponse :

  Super, je ne savais pas qu’on pouvait supprimer les fichiers dans TMP/UPLOAD.
  J’arrive à saturation chez OVH...

  C’est un cas classique, les utilisateurs ne savent pas qu’ils peuvent nettoyer tmp/upload, ou bien ils n’osent pas, il y a donc un problème d’ergo.

  Plusieurs possibilités :

  • demander à l’utilisateur s’il veut supprimer le fichier de tmp/upload quand il l’associe à un article (mais la question peut être mal comprise)
  • le faire automatiquement, ou au bout d’un certain temps