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• How to extract orientation information from videos ?

  23 décembre 2016, par Sid

  After surfing through tons of documentation on the web it seems that the iPhone always shoots the video at a 480x360 aspect ratio and applies a transformation matrix on the video track. (480x360 may change but its always the same for a given device)

  Here is a way of modifying the ffmpeg source within a iOS project and accessing the matrix http://www.seqoy.com/correct-orientation-for-iphone-recorded-movies-with-ffmpeg/

  Here is a cleaner way of finding the transformation matrix in iOS-4
  how to detect (iphone sdk) if a video file was recorded in portrait orientation, or landscape

  How can the orientation of the video be extracted in either of the options below -
  
   iOS 3.2
  
   ffmpeg (through the command line server side)
  
   ruby
  

  Any help will be appreciated.

• ffmpeg override the same file for every second of the video [on hold]

  5 février 2017, par Dorin Pleava

  I want to get one image for every 10 seconds from a livestream/video, but the image should have the same name, meaning I want to override it every cycle.

  This is my command :

  ffmpeg.exe -i http://iphone-streaming.ustream.tv/uhls/17074538/streams/live/iphone/playlist.m3u8 -bt 20M -s 480x300 -vf fps=1/10 -y photo.jpg

  This code works for one image but for the next I get this

  "Could not get frame filename number 2 from pattern ’photo.jpg’ (either set updatefirst or use a pattern like %03d within the filename pattern)
  av_interleaved_write_frame() : Invalid argument"

  If I replace photo.jpeg with photo%03d.jpg I get photo001.jpec, followed by photo002.jpeg, etc.

• Paperclip geometry ignored

  27 mars 2017, par ACIDSTEALTH

  I have a model called Snapshot, which represents a user-recorded video. I want to take the input video file and scale it to fit within a 720x720 box (ImageMagick documentation). I then want to capture some screenshots of the video to represent it in my app. These sizes are specified accordingly in my model.

  I expect the output of this to be an original video with a maximum width of 720px (assuming it was recorded in landscape mode), a large JPG image with a maximum width of 540px, etc.

  When I attach the video file and save the model, the images and video file are processed but the result is not what I expected. The video file has a resolution of 960x720 and the images are all square (540x540, 360x360, etc).

  I’m not sure if I’m doing something wrong or if this is just a bug with Paperclip. Here is my code :

  class Snapshot < ApplicationRecord
  
      has_attached_file :video,
  
          styles: {
  
              original: { geometry: "720x720", format: 'mp4' },
  
              large: { geometry: "540x540", format: 'jpg' },
  
              medium: { geometry: "360x360", format: 'jpg' },
  
              thumb: { geometry: "180x180", format: 'jpg' }
  
          },
  
          default_url: "", processors: [:transcoder]
  
      validates_attachment_content_type :video, content_type: /\Avideo\/.*\Z/
  
      validates_attachment_size :video, less_than: 100.megabytes
  
  end

  I have also tried adjusting the geometry to 720x720>, 540x540>, etc. When I did this, the attachments’ resolution was unchanged, which seems to go completely against my understanding of how ImageMagick geometry works. I have numerous other models with image-only attachments that do not suffer from this issue.

  Here is a snippet from my Gemfile.lock so you can see which versions I am running :

  delayed_paperclip (3.0.1)
  
    activejob (>= 4.2)
  
    paperclip (>= 3.3)
  
  paperclip (5.1.0)
  
    activemodel (>= 4.2.0)
  
    activesupport (>= 4.2.0)
  
    cocaine (~> 0.5.5)
  
    mime-types
  
    mimemagic (~> 0.3.0)
  
  paperclip-av-transcoder (0.6.4)
  
    av (~> 0.9.0)
  
    paperclip (>= 2.5.2)
  
  paperclip-optimizer (2.0.0)
  
    image_optim (~> 0.19)
  
    paperclip (>= 3.4)

  Update
  I retried this with a video recorded in portrait mode (iPhone 6 front-facing webcam) and the video file’s output size was 720x720. The images were still square as before.