Class: Abrizer::AdaptationFinder

Inherits:
Object
  • Object
show all
Defined in:
lib/abrizer/adaptation_finder.rb

Overview

TODO: AdaptationFinder is incomplete. Basically what we want to do is to find out the height, width, and aspect ratio of the original and then determine which adaptations to create. So for a 3:2 video we’ll have 4 adaptations but ought to only create ones that are the same size and smaller than the input file. Adaptations that are larger should not be created. So first we find the aspect ratio to see the value adaptations we could apply and then we select the ones that are the same width and smaller. If there is not an exact match for the All of the aspect ratios here are given based on real files that have come through our workflow, so there might be some missing.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filename) ⇒ AdaptationFinder

Returns a new instance of AdaptationFinder.



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# File 'lib/abrizer/adaptation_finder.rb', line 14

def initialize(filename)
  @filename = filename
  @informer = Abrizer::FfprobeInformer.new(filename)
  find_adaptations
end

Instance Attribute Details

#adaptations ⇒ Object (readonly)

Returns the value of attribute adaptations.



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# File 'lib/abrizer/adaptation_finder.rb', line 13

def adaptations
  @adaptations
end

#info ⇒ Object (readonly)

Returns the value of attribute info.



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# File 'lib/abrizer/adaptation_finder.rb', line 13

def info
  @info
end

Instance Method Details

#ar_16_9_adaptations ⇒ Object

The bitrates here are based on H.264 encoding.



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# File 'lib/abrizer/adaptation_finder.rb', line 46

def ar_16_9_adaptations
  # Average video bitrate from here: https://bitmovin.com/video-bitrate-streaming-hls-dash/
  [
    {width:  256, height: 144, bitrate: 200},
    {width:  512, height: 288, bitrate: 400},
    {width:  768, height: 432, bitrate: 800},
    {width: 1024, height: 576, bitrate: 1200},
    {width: 1280, height: 720, bitrate: 2400},
    {width: 1920, height: 1080, bitrate: 4800},
  ]
end

#ar_4_3_adaptations ⇒ Object

The bitrates here are based on H.264 encoding.



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# File 'lib/abrizer/adaptation_finder.rb', line 36

def ar_4_3_adaptations
  [
    {width: 224, height: 168, bitrate: 200},
    {width: 448, height: 336, bitrate: 400},
    {width: 640, height: 480, bitrate: 800},
    {width: 720, height: 540, bitrate: 1000},
  ]
end

#find_adaptations ⇒ Object

TODO: analyze the incoming file and determine which preset to use



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# File 'lib/abrizer/adaptation_finder.rb', line 21

def find_adaptations
  raw_adaptations = case @informer.display_aspect_ratio
  when "4:3"
    ar_4_3_adaptations
  when "16:9"
    ar_16_9_adaptations
  else
    puts "Unable to find appropriate adaptation set!"
    exit
  end
  adaptations = raw_adaptations.map{|adaptation| Abrizer::Adaptation.new(adaptation)}
  @adaptations = adaptations.select{|adaptation| adaptation.width <= @informer.width}
end