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• Revision 29926 : On branche spip_piwik

  17 juillet 2009, par kent1@… — Log

  On branche spip_piwik

• Color spot in FFmpeg output

  2 juin 2022, par Fabian Garcia

  I work in a company that serves multimedia content to different clients and one of these requests that the videos contain the following specifications :

  


  

  • Codec : H264 High@4.0

  


  • Mode : CBR 1 pass

  


  • Window Buffer : 5 secs

  


  • Frame Rate : 29.97/23.97

  


  • Key Frame Interval : 2 secs

  


  • Bitrate : 4000 Kbps

  


  • Size : 1920x1080

  


  • Window Buffer : 5 secs

  


  • GOP : closed

  


  • GOP size : fixed (no scene change detection)

  


  • Window Buffer : 5 secs

  


  • B Frames : As needed

  


  


  For the above, i build following script :

  


  ffmpeg -hide_banner -nostats -loglevel error -y
-init_hw_device cuda=cuda -hwaccel cuda -hwaccel_device cuda
-i 'video_source.mxf' -filter_hw_device cuda
-filter_complex '[0:v]format=nv12,hwupload,yadif_cuda,scale_cuda=1920:1080[v0]'
-map '[v0]' -c:v h264_nvenc -rc cbr -b:v 4M -bufsize 8M -x264-params "keyint=60:min-keyint=48:no-scenecut" -r '30000/1001' -profile:v high -level:v 4
-map 0:1 -c:a libfdk_aac -b:a 96k -ar 44100 -ac 2 -sample_fmt s16
'output.mp4'


  


  The inconvenience is that the generated output presents some color spots in the scene changes (it's a fade) as can be seen in the attached image.

  


  I could notice that in the output video, the time does not match the input precisely, the output is a few milliseconds ahead, I think that the color spot corresponds to the image that should be shown at that moment in the original video.

  


  Can you see something wrong in script ? Or maybe some concept that i don't know is causing a conflict with the output (This is my first time using ffmpeg).

  


  Thank for your help !

  


  

  


• How to create a fixed image video with ffmpeg that avoids pixelization when it's not maximized ?

  11 août 2022, par Nelson Teixeira

  I have a waiting video in the project I develop. This video is a fixed waiting image with music. I was asked to change the image in the video due to deprecated logo.

  


  So initially I tried just to replace the image in the video using this command :

  


  ffmpeg -i old_waiting_video.mp4 -i new_image.png -filter_complex "[1][0]scale2ref[i][v];[v][i]overlay" -c:a copy new_waiting_video.mp4


  


  This lead to the image became pixelated when the video isn't maximized. When maximized the image is OK. But it looks terrible in the small player.

  


  Here is an image of the problem :

  


  

  


  The above image is the image without zoom out. The left bottom image is a screen capture when I resize it in an image tool and the right bottom is a screen capture of how it looks like in the player.
The image has more than this text, but I thought that wouldn't be appropriate to display my company's logo here. The logo itself is even more pixelized and looks terrible.

  


  So to try to solve this problem I extracted the audio from the file and try to add the image and the audio together to see if it removed the pixelization. So I used this command :

  


  ffmpeg -i audio.m4a -i new_image.png new_waiting_video.mp4


  


  When it failed, searching a bit I came across this other command :

  


  ffmpeg -loop 1 -i new_image.png -i audio.m4a -c:v libx264 -tune stillimage -c:a copy -pix_fmt yuv420p -shortest new_waiting_video.mp4


  


  Again the pixelization ocurred. I know it's possible because this problem doesn't occur in the old logo.

  


  What would be the correct command that allowed that the zoomed out image in the player doesn't pixelate ?

  


  Edit 1

  


  I would also be interested in a command that substitutes the image on the old video as long it doesn't pixelate in the non-maximized player.

  


  Edit 2

  


  

  • Video resolution : 1920x1080

  


  • New image resolution : 1920x1080

  


  • Non-maximized video player size : 640x360

  


  • Video tag : <video src="my-video-url.mp4" style="width: 640px;"></video>