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• FFMPEG documentation example for chromakey doesn't work for green background png file

  15 septembre 2021, par JPM

  Im new in FFMPEG and I try to make just simple green background chroma keying of png images.
In FFMPEG documentation in 38.16 Chromakey - there is an example script :

  



  ffmpeg -i input.png -vf chromakey=green out.png

  



  for which is said that "Make every green pixel in the input image transparent"
That exactly what i wanted.
I tried with many different png images but the result is always a copy of input image.
Also i replaced the word "green" to 0x00FF00 or 0x008000 and still no successes. Only when replacing green to black and then the result is as expected - transparent.
Im working on Windows with pre-build binaries of FFMpeg.
What am I missing ?
Thanks.

  


• Error in Splitting Educational Videos into Segments Using Python (ffmpeg issue) [closed]

  28 décembre 2024, par Yahia Mohamed Hanbal

  I created a Python project to split long educational videos into smaller segments, each focused on a single question. The program uses OCR to detect text on video frames, identifies the word "Question," extracts the number following it, and splits the video whenever the number increases.

  


  here is the video i am tring to split ((video))

  


  Here’s an example of the program’s output :

  


  Video loaded: 14071 frames at 60 FPS, duration: 234.52s  
Frame 480, Time 8.00s, Question: 6  
...  
Frame 12360, Time 206.00s, Question: 7  
Creating segment 1: 8.00s to 206.00s  
Error: module 'ffmpeg' has no attribute 'Error'


  


  I’ve shared the full code in a GitHub repository for reference : Automated Video Scene Cutting.

  


  What the Program Does

  


  

  • Input : A long educational video.

  


  • Processing :

    

    • Detects text in each frame using OCR.

    


    • Searches for the word "Question" followed by a number.

    


    • Monitors when the number increases to identify segment boundaries.

    


    


  


  • Output : Creates video segments corresponding to individual questions.

  


  


  The Problem

  


  The program detects the questions and timestamps correctly, but when it tries to create the segments, I encounter the following error :

  


  Error: module 'ffmpeg' has no attribute 'Error'


  


  What I’ve Tried

  


  

  • Verified the ffmpeg-python library is installed (pip show ffmpeg-python confirms the installation).

  


  • Ensured the ffmpeg binary is accessible from the command line.

  


  • Reviewed the library documentation to ensure the correct usage of ffmpeg.

  


  • Tested with different video files to rule out input-specific issues.

  


  


  Environment Details

  


  

  • OS : Windows 11

  


  • Python Version : 3.9.13

  


  • Key Libraries : ffmpeg-python

  


  


  If anyone has insights into resolving this issue or suggestions for alternative approaches to handle this use case, I’d greatly appreciate your help.

  


  Thank you !

  


• Creating an MP4 video with ffmpeg from timestamped JPEG frames received by pipe

  16 août 2024, par Denis Fevralev

  I need to create a video with following conditions :

  


  

  1. It can only be made from a sequence of JPEG files, each having its timestamp (milliseconds) in the name. The images' durations are not the same, they differ, so i cannot just concat them all and use particular fps

  


  2. There are several tar archives with the images sequences, the archives are kind of huge so I read them from a file storage as an async steam of data and cannot save them on the disk as files. The frames are read and right away put to ffmpeg running process stdin.

  


  3. The images may have different aspect ratios so it's required to make a NxN square and scale the images to fit in with filling the empty space with pads

  


  


  My current solution :

  


  ffmpeg -r $someFpsValue -i - -vf scale=w=$w:h=$h:force_original_aspect_ratio=1,pad=$w:$h:(((ow-iw)/2)):(((oh-ih)/2)) result.mp4


  


  As you can see, it doesn't let me concat the images with correct durations. I know that the concat demuxer can solve the problem of merging images with different durations but seemingly it doesn't work with pipe protocol. I have an idea of evaluating an average fps as (videoFramesCount) / (videoDurationInSeconds) for -r argument, or maybe even counting the fps for each video's second and then getting the avg, but maybe there is a more reliable solution (like some concat demuxer analogue) ?

  


  Thanks in advance :)