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• why transparent drawbox does not work on some video sources ?

  28 mai 2019, par Wang

  It works on smptebars, smptehdbars, testsrc and testsrc2 but not other sources.

  ffplay -loglevel trace -f lavfi -i testsrc=r=1:d=1:size=800x600 -vf "drawbox=x=0:y=0:w='iw/2':h='ih/2':t=max:c=white@0.5"

  When I try this I can see the transparent box. But if I use color, and rgbtestsrc sources it does not work.

  ffplay -loglevel trace -f lavfi -i rgbtestsrc=r=1:d=1:size=800x600 -vf "drawbox=x=0:y=0:w='iw/2':h='ih/2':t=max:c=white@0.5"
  
  ffplay -loglevel trace -f lavfi -i color=c=red:r=1:d=1:size=800x600 -vf "drawbox=x=0:y=0:w='iw/2':h='ih/2':t=max:c=white@0.5"

  after looking at the trace output, it seems the transparency only works on rgb24 and yuv formats (yuv444p, yuv420p, etc.), this is surprising since we normally assume the rgba source can work with alpha channel.

  The following command change the pix_fmt to rgb24, then it works :

  ffplay -loglevel trace -f lavfi -i rgbtestsrc=r=1:d=1:size=800x600 -vf "format=pix_fmts=rgb24,drawbox=x=0:y=0:w='iw/2':h='ih/2':t=max:c=white@0.5"

  The following command change the pix_fmt to rgba, then it does not work :

  ffplay -loglevel trace -f lavfi -i rgbtestsrc=r=1:d=1:size=800x600 -vf "format=pix_fmts=rgba,drawbox=x=0:y=0:w='iw/2':h='ih/2':t=max:c=white@0.5"

  Why is that ? and how can I fix this ?

• How to espace quotes, double quotes and colon inside double quotes when using FFMpeg

  23 septembre 2020, par DnerD.Dev

  I'm trying to get a text written onto a video. I can get it to work when I do it in a single line but not when I need to quote the drawtext inside the double quotes to write two lines.

  


  ffmpeg.exe -i input.ts -vf "[in]drawtext=fontfile=Bebas-Regular.ttf:text='"Day: Sunday"':fontcolor=white:y=(h-h*0.2):x=(w-w*0.95):fontsize=36, drawtext=fontfile=Bebas-Regular.ttf:text='"thing1, thing2, thing3"':fontcolor=white:y=(h-h*0.1):x=(w-w*0.95):fontsize=36[out]" -codec:a copy output1.mp4

  


  I've tried so many combinations of \ but I can't get it to work. The error I get is the following :

  


  Unable to find a suitable output format for 'Sunday':fontcolor=white:y=(h-h*0.2):x=(w-w*0.95):fontsize=36, drawtext=fontfile=Bebas-Regular.ttf:text='thing1,'
Sunday':fontcolor=white:y=(h-h*0.2):x=(w-w*0.95):fontsize=36, drawtext=fontfile=Bebas-Regular.ttf:text='thing1,: Invalid argument


  


  I need the video to have this :

  


  Day: Sunday
Thing1, Thing2, Thing3


  


• FFmpeg : Create a Video Slideshow from PNG Images for MS PowerPoint

  20 septembre 2016, par Klaidonis

  I am using FFmpeg on Windows 7 to create a video from PNG image sequence for Microsoft PowerPoint.

  The best results I have achieved so far, is by using the following command :

  ffmpeg -framerate 10 -start_number 3 -i .\folder\name_%d.png -q:v 0 -c:v libx264 -pix_fmt yuv420p output-video.avi

  It seems perfect, 50 images of total size 30 MB are converted into 200 KB video with no loss in the quality. Placing it in PowerPoint also seems right, but there is a slight color shift (yellow appears darker and possibly more orangish). By using some other conversion options, I obtained a video in PowerPoint where the first image of the video (like album cover art) is exactly as the original but the rest of the video plays with the mentioned color shift.

  When I play this file in VLC, it’s good. Although, if in the settings "Use hardware YUV->RGB conversions" is enabled, colors appear a bit washed out, and white color is a bit gray.

  I also tried to convert the images to a GIF file and at first it seems good but outer edges and numbers from the left and top side are blurred, and the background has turned from white to a bit gray color, although, white segments not on the background are white. The output size is 18 MB. I ended up with a way better GIF 600 KB by converting from the first video file ; just it is slightly more dotted, and the background again is grayish.

  ffmpeg -i output-video.avi output-video.gif

  Could someone help ?