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• 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 !

  


  

  


• ffmpeg -vg -filtercomplex, create gif with color kway and limited fps

  3 février 2020, par daniel

  I need to create a gif file with color key (greenscreen) with 10FPS and specified size. I try to combine -vg and -filter_complex :

  ffmpeg -i testdatei-c.avi -vf "fps=10,scale=320:-1:flags=lanczos" -filter_complex "[0:v]chromakey=0xFFFFFF,split[v0][v1];[v0]palettegen[p];[v1][p]paletteuse" output.gif

  I get the error :

  Filtergraph 'fps=10,scale=320:-1:flags=lanczos' was specified through the -vf/-af/-filter option for output stream 0:0, which is fed from a complex filtergraph.
  
  -vf/-af/-filter and -filter_complex cannot be used together for the same stream.

• ffmpeg alters color scheme when converting images to a video

  12 février 2019, par Flo Ryan

  I am trying to convert a sequence of png images to a video. Unfortunately the video though playing exactly what i want alters the colors.

  The command used to convert the images :

  ffmpeg -framerate 30 -pattern_type glob -i ’*.png’ -c:v libx264 -profile:v high -crf 20 -pix_fmt yuv420p out.mp4

  The original image colors :
  

  The colors as displayed in the video.

  

  How can I circumvent this altering of the colors ?

  EDIT
  I found the answer as posted below.