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• How to encode with LCEVC using FFmpeg ? [closed]

  22 juillet 2020, par progdotpress

  I have searched quite a bit, but I can't seem to find the command line parameters for encoding with LCEVC (Low Complexity Enhancement Video Coding) using FFmpeg.

  


  There is only one article online on this (https://www.streamingmedia.com/Articles/ReadArticle.aspx?ArticleID=139705) and nothing else.

  


  Does anyone know how this is done ? Thank you !

  


• Can I know the exact timestamps of a ffmpeg trim ?

  17 juin 2021, par Vincent Garcia

  I want to trim very long video (e.g. >20h long) and I use ffmpeg this way :

  


  ffmpeg -ss 7200 -i /path/to/my/video.mp4 -t 600 -codec copy out.mp4


  


  This is supposed to provide a trim of 10 minutes starting 2 hours in the input video.
As I read online, by placing -ss before the -i option, I'll get an approximate trim.

  


  Is there a way to know precisely when the trim actually started ?

  


  Thank you.

  


• 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 ?