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• ffmpeg unique frames only

  5 novembre 2013, par William

  I have a video sequence (MPEG1) of 30 fps that is decoded in two ways :

  • opencv_ffmpeg returns 30 images per second, but only 5 of them are unique, while all others are clones of the unique ones.

  • proprietary players (MediaPlayer) returns only the 5 unique frames and "holds" them for (1/5) sec each.

  Is there a way to grab only the unique frames that the coder knows and not the total amount the ffmpeg decoder produces to fulfill the fps rate ?

  I'm developing a tracker and my tracker is forced to run 6 times slower and do many mistakes due to these "cloned frames".

  Does anyone know any technical term to the problem ? Unfortunately, ffmpeg is a black box for an opencv user and the documentation is sparse.

• Evolution #4727 : Des pictos / icônes symboliques pour tout le monde

  14 avril 2021

  Testé brièvement : les mask-image fonctionnent très bien en substitut de la font-face, et ça hérite bien de la taille du texte.
  Donc partir des seuls svg il serait possible de générer à la fois le sprite et la CSS des classes sémantiques, super pratique.
  Je crois que je vais partir là-dessus.

  Un truc bizarre cependant : quand sur la même page on a à la fois un svg et une classe qui utilisent tous deux le même sprite svg, et bien le navigateur le charge 2 fois.
  Peut-être qu’à ce compte là, la classe devrait utiliser les svg indépendants plutôt que le sprite. Enfin bon, ce seront des questions techniques secondaires à résoudre au fil de l’eau dans le plugin, je note juste ça au passage.

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      <span class="tag">span> <span class="attribute-name">xlink:href</span>=<span class="string"><span class="delimiter">"</span><span class="content">sprite.svg#briefcase</span><span class="delimiter">"</span></span><span class="tag">/></span>
  
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• 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.