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• Replacing detected object in a frame with an image.(imageProcessing)

  29 juin 2015, par Kiran Kumar Dash

  Overview :

  I am working on a video creation project. The technology I am using are : imageMagick, php, ffmpeg.

  Current Status :

  Currently the project is able to create videos using images and texts and few basic transitions. The way I am doing it is using imagemagick to create gif using input images(with transition effects in them) and then converting all gifs to videos and atlast concatenating the video together.

  Next Move (My question) :

  I am now set to take it to the next level. So, what I am having is a video(1920x1080) with some white frames(1280x720) that keeps shifting in each frame. I want to replace those white frames appearing in some frames of the video with some images(1280x720) that I wish to use. Please see the image here and you will get an idea : These are just two frames from my video. If you can see carefully the images are shifting(white space is not constant).

  

  

  Expectation :

  So, I want to fill those white space with one of my own image. If the case would have been for only one frame I could have used ffmpeg to overlay image on the exact width and height. But here the white space is not fixed and keeps shifting in all the frames and there are a lot of frames. So, I am looking for something like opencv or some other technology that can be used for object detection in a video or in a set of frames and replace the detected area with some other image.

  I just need a kick. So, if anyone has already worked on something like this just suggest me what technology can I use. Thanks in advance.

• Converting a MOV to WEBP

  27 janvier 2020, par user3469011

  I have a transparent video that I would like to include on my website with a background behind it. I am trying to convert it to .WEBP via ffmpeg.

  I have previously succeeded in converting it to .WEBM, but many browsers don’t support it, so I thought trying .WEBP. Although .WEBP is also not supported on all browsers, there is a JS package to fix that : http://webpjs.appspot.com/

  I have tried (A) from .mov to .webp directly and (B) first from .mov to .webm to then go to .webp
  The conversion to .webp isn’t correct. The new frames are rendered over the old ones. This question had the same problem, but it doesn’t start from a .Mov like me so I doesn’t help me : Transparent animated WebP not clearing frames

  A)

  ffmpeg -i input.mov -vcodec libwebp -lossless 1 -qscale 0 -preset none -an -vsync 0 -loop 1 output4.webp

  B)

  ffmpeg -i input.mov -c:v libvpx -b:v 0.5M -filter:v "crop=in_w*4/6:in_h" -c:a libvorbis -auto-alt-ref 0 -vf scale=960:540 output.webm

  ffmpeg -i output.webm -vcodec libwebp -lossless 1 -q 60 -preset default -an -vsync 0 -loop 1 output.webp

  My goal is to try webp as a way to show transparent animations.
  (GIFs are to big, APNG is not supported and also to big).

  If someone has another alternative, let me know ! I rather not started coding them in actual html/css/js, because an animator already took the time to make them in after effects...

• How to loop over gif file finite number of times while creating mp4 as output with ffmpeg

  16 mai 2020, par in-user

  I am able to convert gif file to mp4 using this command :

  



  ffmpeg -i animated.gif -movflags faststart -pix_fmt yuv420p -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" video.mp4


  



  What I want to do is to loop over gif animation 3 times and convert to mp4.

  



  I am able to do this with 2 shell commands. First one from above and then concatenate the same video 3 times.

  



  ffmpeg -f concat -safe 0 -i <(printf "file '$PWD/video.mp4'\n%.0s" {1..3}) -c copy videoloop.mp4


  



  I have also tried with -ignore_loop 0 option and setting time. It does work but it is not exactly what I am trying to do since I can extend the video but can not make exactly 3 loops.

  



  ffmpeg -ignore_loop 0 -i animated.gif -movflags faststart -pix_fmt yuv420p -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" -t 12 videoloop.mp4


  



  So as you can see I am already able to achieve what I want, but with 2 shell commands :

  



  ffmpeg -i animated.gif -movflags faststart -pix_fmt yuv420p -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" video.mp4
ffmpeg -f concat -safe 0 -i <(printf "file '$PWD/video.mp4'\n%.0s" {1..3}) -c copy videoloop.mp4


  



  Is it possible to do this with only one call to ffmpeg ?

  



  I tried with -loop option for the input file. It doesn't work for gifs. I also tried with -stream_loop. It creates something corrupted.