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• Mix original clip audio with audio of an overlay clip

  28 octobre 2019, par Mr. Messy

  I have a video clip on which I want to add commentary videos (someone talking in a bubble).
  I have 3 commentary videos I need to insert in specific times.

  The video rendering is working well, but I can’t seem to add the audio tracks.
  I tried both amix and amerge, but I got the same issue.

  When I added "[0:1][2:1]amerge ;" I get the follwing :

  

  and the process freezes.

  The full ffmpeg command is as follows :

  ffmpeg -y   -i story.mp4
  
          -loop 1 -i mask.png
  
          -itsoffset 10 -i commentary1.mp4
  
          -itsoffset 22 -i commentary2.mp4
  
          -itsoffset 34 -i commentary3.mp4
  
          -filter_complex "[0:v]scale=w=1/2*in_w:h=1/2*in_h[vid1],
  
                          [2:v]crop=w=480:h=480:x=0:y=120[vid2in],
  
                              [1:v]fifo[2af],[2af]alphaextract[alf2],[vid2in][alf2]alphamerge[vid2alf],
  
                              [vid2alf]format=yuva420p,fade=in:st=10:d=0.5:alpha=1,fade=out:st=22.7294:d=0.5:alpha=1[vid2fade],
  
                              [vid2fade]scale=w=-1:h=160[vid2],
  
                              [vid1][vid2]overlay=790:10:enable='between(t\,10,21)'[out2],
  
                          [3:v]crop=w=480:h=480:x=0:y=120[vid3in],
  
                              [1:v]fifo[3af],[3af]alphaextract[alf3],[vid3in][alf3]alphamerge[vid3alf],
  
                              [vid3alf]format=yuva420p,fade=in:st=22:d=0.5:alpha=1,fade=out:st=32.768733:d=0.5:alpha=1[vid3fade],
  
                              [vid3fade]scale=w=-1:h=160[vid3],
  
                              [out2][vid3]overlay=790:10:enable='between(t\,22,33)'[out3],
  
                          [4:v]crop=w=480:h=480:x=0:y=120[vid4in],
  
                              [1:v]fifo[4af],[4af]alphaextract[alf4],[vid4in][alf4]alphamerge[vid4alf],
  
                              [vid4alf]format=yuva420p,fade=in:st=34:d=0.5:alpha=1,fade=out:st=44.598189:d=0.5:alpha=1[vid4fade],
  
                              [vid4fade]scale=w=-1:h=160[vid4],
  
                              [out3][vid4]overlay=790:10:enable='between(t\,34,45)'[out4]"
  
          -map [out4] -pix_fmt yuv420p -c:v libx264 -crf 18
  
          final_video.mp4

  (mask.png is a circle on a transparent image that crops the video to a bubble)

  Thank you for your help.

• FFMPEG images to video with reverse sequence with other filters

  4 juillet 2019, par Archimedes Trajano

  Similar to this ffmpeg - convert image sequence to video with reversed order

  But I was wondering if I can create a video loop by specifying the image range and have the reverse order appended in one command.

  Ideally I’d like to combine it with this Make an Alpha Mask video from PNG files

  What I am doing now is generating the reverse using https://stackoverflow.com/a/43301451/242042 and combining the video files together.

  However, I am thinking it would be similar to Concat a video with itself, but in reverse, using ffmpeg

  My current attempt was assuming 60 images. which makes vframes x2

  ffmpeg -y -framerate 20 -f image2 -i \
  
    running_gear/%04d.png -start_number 0 -vframes 120 \
  
    -filter_complex "[0:v]reverse,fifo[r];[0:v][r] concat=n=2:v=1 [v]" \
  
    -filter_complex alphaextract[a]
  
    -map 0:v -b:v 5M -crf 20 running_gear.webm 
  
    -map [a] -b:v 5M -crf 20 running_gear-alpha.web

  Without the alpha masking I can get it working using

  ffmpeg -y -framerate 20 -f image2 -i running_gear/%04d.png \
  
    -start_number 0 -vframes 120 \
  
    -filter_complex "[0:v]reverse,fifo[r];[0:v][r] concat=n=2:v=1 [v]" \
  
    -map "[v]" -b:v 5M -crf 20 running_gear.webm

  With just the alpha masking I can do

  ffmpeg -y -framerate 20 -f image2 -i running_gear/%04d.png \
  
    -start_number 0 -vframes 120 \
  
    -filter_complex "[0:v]reverse,fifo[r];[0:v][r] concat=n=2:v=1 [vc];[vc]alphaextract[a]"
  
    -map [a] -b:v 5M -crf 20 alpha.webm

  So I am trying to do it so the alpha mask is done at the same time.

  Although my ultimate ideal would be to take the images, reverse it get an alpha mask and put it side-by-side so it can be used in Ren’py

• Remove random background from video using ffmpeg or Python

  20 avril 2024, par Raheel Shahzad

  I want to remove background from a person's video using ffmpeg or Python. If I record a video at any place, detect the person in the video and then remove anything except that person. Not asking for green or single color background as that can be done through chromakey and I am not looking for that.

  



  I've tried this (https://tryolabs.com/blog/2018/04/17/announcing-luminoth-0-1/) approach but it is giving me output of rectangular box. It is informative enough as area to explore is narrow down enough but still need to remove total background.
I've also tried grabcut (https://docs.opencv.org/4.1.0/d8/d83/tutorial_py_grabcut.html) but that need user interaction otherwise result isn't too good.
I've also tried to use ffmpeg and found this example (http://oioiiooixiii.blogspot.com/2016/09/ffmpeg-extract-foreground-moving.html) but it needs still image so I tried to take background picture before recording video with a person but there are many things required to take difference between background image and video frame.

  



  For opencv approach, I've tried this.

  



  img = cv.imread('pic.png')
mask = np.zeros(img.shape[:2], np.uint8)
bgdModel = np.zeros((1, 65), np.float64)
fgdModel = np.zeros((1, 65), np.float64)
rect = (39, 355, 1977, 2638)
cv.grabCut(img, mask, rect, bgdModel, fgdModel, 5, cv.GC_INIT_WITH_RECT)
mask2 = np.where((mask==2)|(mask==0), 0, 1).astype('uint8')
img = img*mask2[:, :, np.newaxis]
plt.imshow(img), plt.colorbar(), plt.show()


  



  But it is removing some of person's part too.
Also tried ffmpeg way but not a good result.

  



  ffmpeg -report -y -i "img.jpg" -i "vid.mov" -filter_complex "[1:v]format=yuva444p,lut=c3=128[video2withAlpha],[0:v][video2withAlpha]blend=all_mode=difference[out]" -map "[out]" "output.mp4"


  



  All I need is just a person's image/video take under any normal background without user interaction like area selection or any other thing like that. Luminoth has trained data but that is giving box of person not exact person so that I can remove. Any help or guidance to remove background will be appreciated.