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• Flutter FFmpeg - [AVFilterGraph @ 0x88f4b300] No such filter : '"scale'

  9 septembre 2021, par Aryan Shandilya

  So, I am trying to combine an image and an audio file and convert it to a video using ffmpeg in flutter using flutter-ffmpeg but I am getting this error when I am trying to use executewithareguments() function.


  


  I am getting this error ->


  


  I suspected that maybe I should remove the double quotes but even that is giving an error. It would be very helpful if someone tells me what I am doing wrong.
Also, I was using min-gpl version of ffmpeg, I thought that was causing the problem, so I changed it to full-gpl but the error still remains. Any form of help would be great.

  


• Output a video with "slide up" transition using more than 100 images in FFMPEG ?

  9 juillet 2021, par Joseph Ladera Fugata

  I have more than a hundred images of the same size and format that my company wants to display at the big 9:16 (rotated 16:9) screen outside the front gate. It's supposed to be easy but they required me to have it slide from top to bottom, meaning that it should look like a smooth auto scroll effects. I searched here and there but no luck.

  


  I have tried xfade like this :

  


  ffmpeg -loop 1 -i input.txt -filter_complex
"xfade=transition=slideup:duration=10:offset=0,format=yuv420p" output.mp4


  


  It didn't do anything just a bunch of error referring to the inputs. Which is supposed to be just 2 images in the first place.

  


  The next thing I tried was using Concat from someone named @Gyan at his reply HERE and here's my version of the code :

  


  ffmpeg -y -f concat -safe 0 -i input.txt
-vf tile=1x%img_count%,loop=%_my_loop_count_var%:1:0,
crop=iw:ih/%img_count%:0:clip((t-%_start_time%)/%sec_per_img%*ih/%img_count%\,0\,ih*%img_count_minus_one%/%img_count%)
-r 25 -c:v libx264 -preset ultrafast output.mp4


  


  When I played with it, it gives a different output even do the image are all the same dimensions.

  


  I found someone on youtube used this but it is using bash and I am on windows. Unless someone here can convert it to a batch script would be great. I look into it and it seems like he's just V-stacking them kinda like what I did but there's more. I know I could have gone through win bash but I doubt the script will run on a non-Unix environment just by having bash, and I'm not yet familiar with Cygwin either.

  


  I also did tried other options posted by others here, I just forgot to bookmark them, but non of them works on more than a hundred images.

  


  I love to hear a response if anyone can help.

  


• How to averagely extract frames from a video using ffmpeg by specifying "fps"

  14 juin 2021, par alanzzz

  I have a job of using ffmpeg to extract the frames averagely from a video, with different fps. I use this command for it.

  


  ffmpeg -i input.mp4 -r specified_fps -q:v 2 image %4d.png

  


  And I have 3 questions about this task.

  


  

  1. what I expect is that if I double the fps, the number of extracted frames will also get doubled. However, that's not the case. Take one of the input videos as an example.

  


  


  video info

  


  

  • Duration : 1min18s

  


  • Total number of frames : 2340

  


  • Frame rate mode : constant (CFR)

  


  • Frame rate : 30.0 FPS

  


  


  Config setting & results

  


  

  • FPS=1 => number of frames=80

  


  • FPS=2 => number of frames=158 (2x80-2)

  


  • FPS=3 => number of frames=236 (3x80-4)

  


  • FPS=5 => number of frames=392 (5x80-8)

  


  


  Is it possible for me to get the exact doubled number of frames when fps get doubled ? In such case, number of frames is 160 for FPS=2, 240 for FPS=3, 400 for FPS=5.

  


  


  2. I check for the output images, the extracted frames in different fps are totally different from each other. In other words, for example, the 1st image for fps=1 is not the same as the 1st image for fps=2. Is that legitimate ? And is it possible for me the get some identical images for different fps ?

     


  


  3. The last problem is that for some videos I use, the difference between the 1st and 2nd image is different from the difference between the 2nd and 3rd. While for the remaining images, the differences become average. To be specific, there is only a slight change from 1st to 2nd frame, while for 2nd to 3rd, 3rd to 4th, and so on, the changes are the same, which is normally distributed according to the specified FPS. I am wondering why such a case happens ? Does it related to the I-frame, B-frame, P-frame, GOP or IDR ?

     


  


  


  I am new to this field and cannot find some useful info from other places. I've tried my best to describe my questions clearly. Feel free to leave some comments. Any help would do me a great favor. Thanks in advance !