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• colored TV-Noise with windows

  8 janvier 2024, par LookAndSee

  I have some question to the colored noise at image 2 of the following thread :

  


  Simulating TV noise

  


  

  • how can i get this in windows ? I like a random pattern consisting of red, green, blue, white and black points, like 255:0:0, 0:255:0, 0:0:255, 255:255:0, 0:0:0 and 255:255:255 - no pink, no orange, no cyan ... at the first step.

  


  


  but random in all 3 places always delievers (with ceil, floor or round) whole black, or whole white or bw-noise :-(
does it mean, the random(1) per point is 3 times the same in one computing-cycle ?

  


  Any suggestion ?

  


  This is what i tried :

  


  ffmpeg -y -f lavfi -i nullsrc=s=1280x720 -filter_complex "geq=r=(round(random(1)))*255:g=(round(random(1)))*255:b=(round(random(1)))*255;aevalsrc=-2+random(0)" -t 5 output.mkv


  


• ffmpeg : combine filter_complex trim, overlay and concat

  4 octobre 2015, par jb_alvarado

  I try to combine different video and audio clips with trimming and a logo on top.

  My syntax looks like this :

  ffmpeg -i "$introVid" -i "$introAud" -i "$mainVid" -i "$mainAud" -i "$outroVid" -i "$outroAud" -i "$logo" -i "$mainVid" -i "$mainAud" \
  
  -filter_complex \
  
  "[2:0]trim=0.4:60[trimV1]; \
  
   [3:0]atrim=0.4:60[trimA1]; \
  
   [trimV1][6:v]overlay=main_w-overlay_w-20:15,fade=in:s=2:d=0.5:alpha=1,fade=out:s=60:d=0.5:alpha=1[fade]; \
  
   [7:0]trim=60.2:72[trimV2]; [8:0]atrim=60.2:72[trimA2]; \
  
   [0:0] [1:0] [fade] [trimA1] [4:0] [5:0] [trimV2] [trimA2] concat=n=4:v=1:a=1[cv][a]; \
  
   [cv]scale=864:480:flags=gauss:interl=0[scal]" \
  
  -map "[scal]" -map "[a]" -pix_fmt yuv420p -c:v libx264 -preset fast -y "$out"

  It works mostly, but the problem is that I get a black video, with the same length then the main video, on the 3rd place. Interesting is also, when I watch the ffmpeg process, it hangs shortly on time 1:26min and then it jumps to 2:40min. Normally the complete test video have around 1:30min.

  The output what I get is at the moment :

  ([intro][trimmed main with logo][black video][outro][credits]) <- the black video part is to much.

• ffmpeg : Generate empty audio and video (working for video)

  17 septembre 2021, par David Ferris

  I'm trying to generate a black video with FFMPEG. I have accomplished this with the following :

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  ffmpeg -t 5 -f lavfi -i color=c=black:s=1920x1080 -c:v libx264 -tune stillimage -pix_fmt yuv420p out.mp4


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  Unfortunately this video doesn't have any audio tracks. Following this, I have tried to insert -i anullsrc=channel_layout=stereo:sample_rate=44100 :

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  ffmpeg -t 5 -i anullsrc=channel_layout=stereo:sample_rate=44100 -f lavfi -i color=c=black:s=1920x1080 -c:v libx264 -tune stillimage -pix_fmt yuv420p out.mp4


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  Unfortunately this gives the error :

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  anullsrc=channel_layout=stereo:sample_rate=44100 : No such file or&#xA;directory

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  How can I modify my initial script to generate a video with empty audio ?

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