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• ffmpeg watermark transparent background

  19 février 2018, par Mihai Vilcu

  I’m trying to add a watermark to a video file but i’m having problems with the background of the watermark because i want it to be transparent.

  My approach is like this : i make a png file the size of the video with transparent background like this

  $im = imagecreatetruecolor($width, $height); 
  
  $almostblack = imagecolorallocate($im,254,254,254); 
  
  imagefill($im,0,0,$almostblack); 
  
  $black = imagecolorallocate($im,0,0,0); 
  
  imagecolortransparent($im,$almostblack); 
  
  
  
  $textcolor = imagecolorallocate($im, 255, 0, 0);
  
  
  
  // Write the string at the top left
  
  imagestring($im, 5, 0, 0, 'Hello world!', $textcolor);
  
  
  
  imagepng($im, $img);
  
  imagedestroy($im);

  and then i add it to the video like this

  exec("/usr/bin/ffmpeg -y -i '$file->path' -sameq -vf 'movie=$img [logo]; [in][logo] overlay=main_w-overlay_w:main_h-overlay_h [out]' '$new_path'");

  the watermark is added but it’s background is not transparent.

  Any idea what i’m doing wrong ?

  UPDATE : it turns out it works just fine for other png images so the problem must be in the way i build the png file any ideas why it doesn’t work that way ?

• PyGame video get out of sync

  8 novembre 2020, par jas_123

  So, I want to make a video player that plays the video and the audio in sync. I also don't want to use ffmpeg because I would like to make my script not need a dependency of ffmpeg and force my friends to install ffmpeg to their computer and set the path and stuff. So right now my code is :

  


  from moviepy.editor import *
import pygame

pygame.display.set_caption('Hello World!')

clip = VideoFileClip('yeetus.mp4')
clip.preview(fps=30)

pygame.quit()


  


  (From How can I play a mp4 movie using Moviepy and Pygame)

  


  When I try to move the window somewhere else it freezes right and the audio kinda just iterates in a specific timestamp. But when you stop dragging it, the audio plays where it was, but the video is out of sync. Is there a fix to this issue ? If not, is there an alternative ? Thanks

  


  edit : still open to answers btw

  


• How to add two video filters in one command line which has transcoding done by two GPUs ?

  3 août 2022, par Max Dax

  I have two video filters :

  


  


  -vf "hwdownload, drawtext=fontfile=/usr/share/fonts/TTF/Verdana.ttf:text='Hello World',
format=nv12, hwupload"

  


  


  and

  


  


  -vf "select='gt(scene,0.04)'" -vsync 0 'snapshot.png'

  


  


  How can I add these two video filters to the below command line which does transcoding from a webcam livestream of MJPG to HEVC using two GPUs ? :

  


  


  ffmpeg
-init_hw_device cuda=decdev :/dev/dri/renderD129
-init_hw_device vaapi=encdev :/dev/dri/renderD128
-hwaccel cuda
-hwaccel_device decdev
-hwaccel_output_format cuda
-c:v mjpeg_cuvid
-f v4l2 -input_format mjpeg -framerate 30 -video_size 1920x1080
-i /dev/video0
-filter_hw_device encdev
-c:v hevc_vaapi webcam.mp4"

  


  


  Basically what I am trying to do is using FFMPEG to transcode and record a live webcam stream and also at the same time take snapshots when motion is detected.

  


  Thanks