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• c# - WAV file trimming and adding silence

  16 mai 2018, par Piotr C

  I have two recordings of same event, different lengths, started at different times. I want to synchronize them, time offset is known. I want to achieve the following :

  1. Align second one in time by the time offset.
  2. Trim second one to match the length of the first one
  3. When there is nothing to trim, add silence to match the length of the first one.

     I found the way to trim the audio, but I couldn’t find solution for adding silence. Is there any way to do this with NAudio, ffmpeg or Aurio ?

• How to put a png onto an mp4/gif using imagemagick ?

  24 juillet 2022, par Harrison

  TLDR : How do I convert an MP4 to GIF without sacrificing quality ? How can I lay a PNG on a GIF without sacrificing quality ? And how to get rid of the flicker from combining them ?

  


  So I have an MP4 that is 3000x3000 and a PNG that is 1000x1000.

  


  The end result that I want is a GIF that is 1000x1000 where the PNG is layered on top of the MP4 as a background.

  


  These are the step I tried and the issues I am running into. Mainly the issues I am running into are a loss in quality.

  


  MP4 to GIF :

  


  


  1. I have converted the MP4 to a gif with ffmpeg -i background.mp4 background.gif. Result : A major loss of quality in the gif.

     


  


  2. Instead of that - I tried an online converter. Works better but would like to do it on my own. But I will use this GIF from the online converter in the next examples. Still a slight loss of quality but not near as bad.

     


  


  3. I have sized down my gif using convert temporary.gif -coalesce -resize 1000x1000 smaller.gif. (Have also tried with specifying the -size 3000x3000 but no difference really.) Another minor loss of quality there.

     


  


  


  PNG ontop of GIF - Trial 1

  


  

  1. I have converted my PNG to a single page GIF with convert front.png front.gif (Along with some other options). Loses quality, anything that fades or is semi see through gets turned into a solid pixel.

  


  2. Duplicated this page a bunch of times to match number of pages in my background gif using convert front.gif front.gif front.gif multiple times.

  


  3. Merged background and front together with convert background.gif -coalesce null: front.gif -layers composite both.gif. Little more lose of quality and some flickering on the foreground..? Tried some other variations but thats the best I got.

  


  


  PNG on GIF - Trial 2

  


  

  1. Instead of making a GIF of the PNG, I am just using the original PNG with the background.gif like this convert smaller.gif -coalesce null: front.png -layers composite -layers optimize both.gif. This one comes out weird. The from image is very different looking in color and flickery. Not gonna work.

  


  2. Tried without optimization. convert smaller.gif -coalesce null: front.png -layers composite test.gif. This on is closer. The foreground looks great, but is just flickery still ! Again the background is not great but it doesn't seem to have much more impact from after the original mp4 conversion. Did this without -coalesce and still get the same output.

  


  


  The best I can get is a decent front image with details preserved - but flickery. On top of a lossy background.

  


  How can I go about doing this with imagemagick or some other library ?

  


• Configuring PHPVideoToolkit library

  21 novembre 2013, par mrpotatohead

  I'm trying to set up PHPVideoToolkit to use for converting videos on a server and can't seem to get the documentation/examples working. After setting the basic configuration, as well as making some slight changes to even be able to see the documentation I'm getting the following error (among others) :

  Declaration of PHPVideoToolkit\FfmpegProcess::getExecBuffer() should be compatible
  
  with that of PHPVideoToolkit\ProcessBuilder::getExecBuffer()

  and this one, several times :

  Undefined offset: 2
  
          [2] => /var/www/media_html/phpvideotoolkit-v2/src/PHPVideoToolkit/FfmpegParserAbstract.php

  After digging around for a little bit in various source files I realized I'm probably doing more harm than good changing stuff around and am probably doing something wrong.
  I'm stumped as to how to fix this so thanks in advance to anyone who knows how to.