Recherche avancée

Sur d’autres sites (8966)

• Raising and Rescuing Custom Exception

  24 décembre 2013, par cmw

  I'm using Rails 3 with Carrierwave and FFMPEG to handle video uploads and encoding.

  In my uploader, I'm using FFMPEG to grab the duration of the video from cache before storing it.

  I'd like to raise a custom exception if the video's duration exceeds a specific length and then route the user accordingly. I've spent quite a bit of time trying to figure out how to create, raise and rescue my own custom exceptions in Rails – but, I've had no luck.

  Some posts I've used to try to piece this together include this stack overflow post and this article on customized exception handling in Rails 3. I've had no luck yet.

  I'm hoping someone can offer guidance on the proper approach to this. My mind is blown.

  Below is what my uploader looks like :

  class VideoUploader < CarrierWave::Uploader::Base
  
  
  
    before :store, :ffmpeg
  
  
  
    # Set storage type
  
    storage :fog
  
  
  
    # Override the directory where uploaded files will be stored.
  
    def store_dir
  
      "#{model.class.to_s.underscore}/videos/#{model.id}"
  
    end
  
  
  
    # Add a white list of extensions which are allowed to be uploaded.
  
    def extension_white_list
  
      %w(mov avi mp4 mkv wmv mpg)
  
    end
  
  
  
    def full_cache_path
  
      "#{::Rails.root}/public/#{cache_dir}/#{cache_name}"
  
    end
  
  
  
    private 
  
  
  
    def ffmpeg(*args)
  
      @model.video.cache_stored_file!
  
      movie = FFMPEG::Movie.new("#{model.video.full_cache_path}")
  
      if movie.duration > 600
  
        raise "my custom exception will go here one day"
  
      end
  
    end
  
  
  
  end

• FFMPEG seems to not be reading files from .txt file [closed]

  15 août 2021, par user3266908

  I have the following command

  


  ffmpeg -f concat -safe 0 -i C:\location1\location2\01\video.txt  -f  concat  -safe 0 -i C:\lcation2\location2\01\image.txt -filter_complex_script C:\location1\location2\01\script.txt C:\PollyBot\audio\morning.mp4


  


  the video.txt , image.txt and the script.txt reads as follow. Side note the script.txt file applies a filter.

  


  video.txt
file 'c:\videos\video.mp4'


images.txt
file 'c:\images\image01.png'
file 'c:\images\image02.png'

script
[0:V]scale=1080:-1,pad=0:1920:0:(oh-ih)/2[vid];
[vid][1:0]overlay=enable='between(t,10,15)'[i1];
[i1][1:1]overlay=enable='between(t,20,35)'


  


  What happens is that the scale of the video is scaled but streams for the images only every displays 1 images and never returns a stream for the second image. I have tried different versions of ffmpeg, removing the overlay and just forcibly calling the second stream with out it being listed but nothing works. I also noticed that this issue is present in the other .txt files as well. It seems like ffmpeg only reads the first item in the .txt file and ignores everything else. this issue is repeatable in the other files as well. Just one video, the first is seen. I'm new to FFMPEG so any pointers is welcome. Keep in mind that I'm doing this all from the windows machine and if I run the command with just one image/overlay files it runs with out issue.

  


  

  


  To me it looks that something is wrong with my .txt file and that it is unable to read anything past the first line since if I'm just overlaying one item it works just fine.

  


• How to get FFmpeg to consistently apply speed effect to first few frames ?

  16 janvier 2021, par melody_florum

  I am using FFmpeg to apply speed effects to short gifs and videos and I noticed strange stuttering on looping gifs when sped up. I manually tested and found what was going on. FFmpeg failed to apply the speed filter to the first few frames of the video.

  


  I started with this file, which loops between the numbers "1 2 3 4" every frame.

  


  123410fps.mp4

  


  I then ran the command ffmpeg -i 123410fps.mp4 -vf setpts=0.5*PTS 123410fpsout.mp4

  


  That left me with this file : 123410fpsout.mp4

  


  On close analysis, I discovered that the output file didn't show a repeating 1 3 1 3 or 2 4 2 4 pattern, but shows 1 2 3 4 1 3 1 3 1 3... the speed effect didn't apply for the first few frames

  


  I apologize if it sounds like i'm being super nitpicky, but my usage for this is on very short gifs and videos where this effect is very apparent. How can I prevent this effect from happening and have a 100% consistent speed effect applied to the video ? I don't mind using other non-ffmpeg software but a CLI solution that works easily for most videos is ideal.

  


  In case anyone is wondering, I don't use ffmpeg to encode gifs, i use gifski from ffmpeg exported image sequences. The problem shows up even when no gifs are used, so it's not a gifski problem.