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• FFmpeg - Xstack mutiple inputs for mosaic video output - extra output Blank screen is always green

  16 août 2020, par Dennisski

  I have a website where we combine multple videos with ffmpeg xstack. Its an automated process. When there is not an even number of videos the blank tiles in the mosaic are green. I am trying to figure out how to make the spare blanks Black.

  


  I have tried xstack=inputs=2:fill='black':layout=0_0 (this gives an error object not found) also tried -filter_complex "color=s=1920x1080:c=black".

  


  Any suggestions ? Here is entire command :

  


  ffmpeg -i video1 -i video1 -i video1 -i video1 -i video1 -i video1 -i video1 \ 
    -i video1 -i video1 -filter_complex \
    "color=s=1920x1080:c=black;[0:v] setpts=PTS-STARTPTS, scale=qvga [a0];[1:v] setpts=PTS-STARTPTS, scale=qvga [a1];[2:v] setpts=PTS-STARTPTS, scale=qvga [a2];[3:v] setpts=PTS-STARTPTS, scale=qvga [a3];[4:v] setpts=PTS-STARTPTS, scale=qvga [a4];[5:v] setpts=PTS-STARTPTS, scale=qvga [a5];[6:v] setpts=PTS-STARTPTS, scale=qvga [a6];[7:v] setpts=PTS-STARTPTS, scale=qvga [a7];[8:v] setpts=PTS-STARTPTS, scale=qvga [a8];[a0][a1][a2][a3][a4][a5][a6][a7][a8]xstack=inputs=9:layout=0_0|w0_0|w0+w1_0|0_h0|w0_h0|w0+w1_h0|0_h0+h1|w0_h0+h1|w0+w1_h0+h1[out] " \
    -map "[out]" output


  


• fallback input when blackscreen ffmpeg

  23 novembre 2022, par renadr

  I would like to have a "fallback" video when using the ffmpeg command. The goal is that I broadcast a video and once this one displays an almost black screen, there should be a switch to the fallback, and re-switch when the black screen is over. I know that we can detect the "blackframe" but I'm lost then.. If anyone have an idea ?

  


  I'm at this point for the moment (I'm using streamlink for getting the input) :

  


  streamlink <> best -O | ffmpeg -re -i pipe:0 -c:v libx264 -vf "blackframe=amount=40:thresh=5" -c:a aac -strict -2 -f flv <> | grep blackframe


  


  thank you

  


• ffmpeg concat creates video with frame timings off by 0.1-0.2 seconds [closed]

  17 octobre 2023, par brain-geek

  I am trying to create some variable frame rate video for test data, however frame timings of the result are consistently off. I tried both ffmpeg 4 and ffmpeg 6, but having same results. I am using example from the website as a reference.

  


  Here is the script to generate video :

  


  rm -f framelist.txt output.mp4

convert -size 640x480 -gravity center -background black -fill purple label:0-2 -units PixelsPerInch -density 254 0-2.png
echo "file '0-2.png'" >> framelist.txt
echo "duration 2" >> framelist.txt
convert -size 640x480 -gravity center -background black -fill purple label:2-2.5 -units PixelsPerInch -density 254 2-2.5.png
echo "file '2-2.5.png'" >> framelist.txt
echo "duration 0.5" >> framelist.txt
convert -size 640x480 -gravity center -background black -fill purple label:2.5-3 -units PixelsPerInch -density 254 2.5-3.png
echo "file '2.5-3.png'" >> framelist.txt
echo "duration 0.5" >> framelist.txt
convert -size 640x480 -gravity center -background black -fill purple label:3-3.25 -units PixelsPerInch -density 254 3-3.25.png
echo "file '3-3.25.png'" >> framelist.txt
echo "duration 0.25" >> framelist.txt
convert -size 640x480 -gravity center -background black -fill purple label:3.25-3.5 -units PixelsPerInch -density 254 3.25-3.5.png
echo "file '3.25-3.5.png'" >> framelist.txt
echo "duration 0.25" >> framelist.txt
convert -size 640x480 -gravity center -background black -fill purple label:3.5-3.75 -units PixelsPerInch -density 254 3.5-3.75.png
echo "file '3.5-3.75.png'" >> framelist.txt
echo "duration 0.25" >> framelist.txt
convert -size 640x480 -gravity center -background black -fill purple label:3.75-4 -units PixelsPerInch -density 254 3.75-4.png
echo "file '3.75-4.png'" >> framelist.txt
echo "duration 0.25" >> framelist.txt
convert -size 640x480 -gravity center -background black -fill purple label:4-10 -units PixelsPerInch -density 254 4-10.png
echo "file '4-10.png'" >> framelist.txt
echo "duration 6" >> framelist.txt
convert -size 640x480 -gravity center -background black -fill purple label:10-20 -units PixelsPerInch -density 254 10-20.png
echo "file '10-20.png'" >> framelist.txt
echo "duration 10" >> framelist.txt
echo "file '10-20.png'" >> framelist.txt

ffmpeg -f concat -i framelist.txt -vsync vfr -pix_fmt yuv420p output.mp4


  


  When after that I do ffprobe, I get not expected frame timings :

  


  $ ffprobe -v error -select_streams v:0 -show_frames output.mp4|grep pts_time
pts_time=0.000000
pts_time=2.000000
pts_time=2.520000
pts_time=3.000000
pts_time=3.240000
pts_time=3.520000
pts_time=3.760000
pts_time=4.000000
pts_time=10.000000
pts_time=20.000000


  


  First and second are correct - 0 and 2, however third should be 2.5 instead of 2.52 . Third is once more correct as 3.0, but fourth should be 3.25, not 3.24 . Last 3 are correct as well (4, 10, 20).

  


  What could be the problem, and how do I get the correct frame timings here ?