invidious/src/invidious/videos/storyboard.cr
2024-08-17 12:20:53 +02:00

123 lines
4.0 KiB
Crystal

require "uri"
require "http/params"
module Invidious::Videos
struct Storyboard
# Template URL
getter url : URI
getter proxied_url : URI
# Thumbnail parameters
getter width : Int32
getter height : Int32
getter count : Int32
getter interval : Int32
# Image (storyboard) parameters
getter rows : Int32
getter columns : Int32
getter images_count : Int32
def initialize(
*, @url, @width, @height, @count, @interval,
@rows, @columns, @images_count
)
authority = /(i\d?).ytimg.com/.match!(@url.host.not_nil!)[1]?
@proxied_url = URI.parse(HOST_URL)
@proxied_url.path = "/sb/#{authority}/#{@url.path.lchop("/sb/")}"
@proxied_url.query = @url.query
end
# Parse the JSON structure from Youtube
def self.from_yt_json(container : JSON::Any, length_seconds : Int32) : Array(Storyboard)
# Livestream storyboards are a bit different
# TODO: document exactly how
if storyboard = container.dig?("playerLiveStoryboardSpecRenderer", "spec").try &.as_s
return [Storyboard.new(
url: URI.parse(storyboard.split("#")[0]),
width: 106,
height: 60,
count: -1,
interval: 5000,
rows: 3,
columns: 3,
images_count: -1
)]
end
# Split the storyboard string into chunks
#
# General format (whitespaces added for legibility):
# https://i.ytimg.com/sb/<video_id>/storyboard3_L$L/$N.jpg?sqp=<sig0>
# | 48 # 27 # 100 # 10 # 10 # 0 # default # rs$<sig1>
# | 80 # 45 # 95 # 10 # 10 # 10000 # M$M # rs$<sig2>
# | 160 # 90 # 95 # 5 # 5 # 10000 # M$M # rs$<sig3>
#
storyboards = container.dig?("playerStoryboardSpecRenderer", "spec")
.try &.as_s.split("|")
return [] of Storyboard if !storyboards
# The base URL is the first chunk
base_url = URI.parse(storyboards.shift)
return storyboards.map_with_index do |sb, i|
# Separate the different storyboard parameters:
# width/height: respective dimensions, in pixels, of a single thumbnail
# count: how many thumbnails are displayed across the full video
# columns/rows: maximum amount of thumbnails that can be stuffed in a
# single image, horizontally and vertically.
# interval: interval between two thumbnails, in milliseconds
# name: storyboard filename. Usually "M$M" or "default"
# sigh: URL cryptographic signature
width, height, count, columns, rows, interval, name, sigh = sb.split("#")
width = width.to_i
height = height.to_i
count = count.to_i
interval = interval.to_i
columns = columns.to_i
rows = rows.to_i
# Copy base URL object, so that we can modify it
url = base_url.dup
# Add the signature to the URL
params = url.query_params
params["sigh"] = sigh
url.query_params = params
# Replace the template parts with what we have
url.path = url.path.sub("$L", i).sub("$N", name)
# This value represents the maximum amount of thumbnails that can fit
# in a single image. The last image (or the only one for short videos)
# will contain less thumbnails than that.
thumbnails_per_image = columns * rows
# This value represents the total amount of storyboards required to
# hold all of the thumbnails. It can't be less than 1.
images_count = (count / thumbnails_per_image).ceil.to_i
# Compute the interval when needed (in general, that's only required
# for the first "default" storyboard).
if interval == 0
interval = ((length_seconds / count) * 1_000).to_i
end
Storyboard.new(
url: url,
width: width,
height: height,
count: count,
interval: interval,
rows: rows,
columns: columns,
images_count: images_count,
)
end
end
end
end