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Refactor WebVTT building logic into WebVTT::Builder (#4070)

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Samantaz Fox 2023-10-07 19:53:29 +02:00
commit 1caaf63c8a
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5 changed files with 160 additions and 91 deletions
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64
spec/helpers/vtt/builder_spec.cr Normal file
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@ -0,0 +1,64 @@
require "../../spec_helper.cr"
MockLines = [
{
"start_time": Time::Span.new(seconds: 1),
"end_time": Time::Span.new(seconds: 2),
"text": "Line 1",
},
{
"start_time": Time::Span.new(seconds: 2),
"end_time": Time::Span.new(seconds: 3),
"text": "Line 2",
},
]
Spectator.describe "WebVTT::Builder" do
it "correctly builds a vtt file" do
result = WebVTT.build do |vtt|
MockLines.each do |line|
vtt.cue(line["start_time"], line["end_time"], line["text"])
end
end
expect(result).to eq([
"WEBVTT",
"",
"00:00:01.000 --> 00:00:02.000",
"Line 1",
"",
"00:00:02.000 --> 00:00:03.000",
"Line 2",
"",
"",
].join('\n'))
end
it "correctly builds a vtt file with setting fields" do
setting_fields = {
"Kind" => "captions",
"Language" => "en",
}
result = WebVTT.build(setting_fields) do |vtt|
MockLines.each do |line|
vtt.cue(line["start_time"], line["end_time"], line["text"])
end
end
expect(result).to eq([
"WEBVTT",
"Kind: captions",
"Language: en",
"",
"00:00:01.000 --> 00:00:02.000",
"Line 1",
"",
"00:00:02.000 --> 00:00:03.000",
"Line 2",
"",
"",
].join('\n'))
end
end

67
src/invidious/helpers/webvtt.cr Normal file
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@ -0,0 +1,67 @@
# Namespace for logic relating to generating WebVTT files
#
# Probably not compliant to WebVTT's specs but it is enough for Invidious.
module WebVTT
# A WebVTT builder generates WebVTT files
private class Builder
def initialize(@io : IO)
end
# Writes an vtt cue with the specified time stamp and contents
def cue(start_time : Time::Span, end_time : Time::Span, text : String)
timestamp(start_time, end_time)
@io << text
@io << "\n\n"
end
private def timestamp(start_time : Time::Span, end_time : Time::Span)
timestamp_component(start_time)
@io << " --> "
timestamp_component(end_time)
@io << '\n'
end
private def timestamp_component(timestamp : Time::Span)
@io << timestamp.hours.to_s.rjust(2, '0')
@io << ':' << timestamp.minutes.to_s.rjust(2, '0')
@io << ':' << timestamp.seconds.to_s.rjust(2, '0')
@io << '.' << timestamp.milliseconds.to_s.rjust(3, '0')
end
def document(setting_fields : Hash(String, String)? = nil, &)
@io << "WEBVTT\n"
if setting_fields
setting_fields.each do |name, value|
@io << name << ": " << value << '\n'
end
end
@io << '\n'
yield
end
end
# Returns the resulting `String` of writing WebVTT to the yielded `WebVTT::Builder`
#
# ```
# string = WebVTT.build do |vtt|
# vtt.cue(Time::Span.new(seconds: 1), Time::Span.new(seconds: 2), "Line 1")
# vtt.cue(Time::Span.new(seconds: 2), Time::Span.new(seconds: 3), "Line 2")
# end
#
# string # => "WEBVTT\n\n00:00:01.000 --> 00:00:02.000\nLine 1\n\n00:00:02.000 --> 00:00:03.000\nLine 2\n\n"
# ```
#
# Accepts an optional settings fields hash to add settings attribute to the resulting vtt file.
def self.build(setting_fields : Hash(String, String)? = nil, &)
String.build do |str|
builder = Builder.new(str)
builder.document(setting_fields) do
yield builder
end
end
end
end

39
src/invidious/routes/api/v1/videos.cr
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@ -101,20 +101,17 @@ module Invidious::Routes::API::V1::Videos
if caption.name.includes? "auto-generated"
caption_xml = YT_POOL.client &.get(url).body
settings_field = {
"Kind" => "captions",
"Language" => "#{tlang || caption.language_code}",
}
if caption_xml.starts_with?("<?xml")
webvtt = caption.timedtext_to_vtt(caption_xml, tlang)
else
caption_xml = XML.parse(caption_xml)
webvtt = String.build do |str|
str << <<-END_VTT
WEBVTT
Kind: captions
Language: #{tlang || caption.language_code}
END_VTT
webvtt = WebVTT.build(settings_field) do |webvtt|
caption_nodes = caption_xml.xpath_nodes("//transcript/text")
caption_nodes.each_with_index do |node, i|
start_time = node["start"].to_f.seconds
@ -127,9 +124,6 @@ module Invidious::Routes::API::V1::Videos
end_time = start_time + duration
end
start_time = "#{start_time.hours.to_s.rjust(2, '0')}:#{start_time.minutes.to_s.rjust(2, '0')}:#{start_time.seconds.to_s.rjust(2, '0')}.#{start_time.milliseconds.to_s.rjust(3, '0')}"
end_time = "#{end_time.hours.to_s.rjust(2, '0')}:#{end_time.minutes.to_s.rjust(2, '0')}:#{end_time.seconds.to_s.rjust(2, '0')}.#{end_time.milliseconds.to_s.rjust(3, '0')}"
text = HTML.unescape(node.content)
text = text.gsub(/<font color="#[a-fA-F0-9]{6}">/, "")
text = text.gsub(/<\/font>/, "")
@ -137,12 +131,7 @@ module Invidious::Routes::API::V1::Videos
text = "<v #{md["name"]}>#{md["text"]}</v>"
end
str << <<-END_CUE
#{start_time} --> #{end_time}
#{text}
END_CUE
webvtt.cue(start_time, end_time, text)
end
end
end
@ -215,11 +204,7 @@ module Invidious::Routes::API::V1::Videos
storyboard = storyboard[0]
end
String.build do |str|
str << <<-END_VTT
WEBVTT
END_VTT
WebVTT.build do |vtt|
start_time = 0.milliseconds
end_time = storyboard[:interval].milliseconds
@ -231,12 +216,8 @@ module Invidious::Routes::API::V1::Videos
storyboard[:storyboard_height].times do |j|
storyboard[:storyboard_width].times do |k|
str << <<-END_CUE
#{start_time}.000 --> #{end_time}.000
#{url}#xywh=#{storyboard[:width] * k},#{storyboard[:height] * j},#{storyboard[:width] - 2},#{storyboard[:height]}
END_CUE
current_cue_url = "#{url}#xywh=#{storyboard[:width] * k},#{storyboard[:height] * j},#{storyboard[:width] - 2},#{storyboard[:height]}"
vtt.cue(start_time, end_time, current_cue_url)
start_time += storyboard[:interval].milliseconds
end_time += storyboard[:interval].milliseconds

41
src/invidious/videos/caption.cr
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@ -52,17 +52,13 @@ module Invidious::Videos
break
end
end
result = String.build do |result|
result << <<-END_VTT
WEBVTT
Kind: captions
Language: #{tlang || @language_code}
settings_field = {
"Kind" => "captions",
"Language" => "#{tlang || @language_code}",
}
END_VTT
result << "\n\n"
result = WebVTT.build(settings_field) do |vtt|
cues.each_with_index do |node, i|
start_time = node["t"].to_f.milliseconds
@ -76,29 +72,16 @@ module Invidious::Videos
end_time = start_time + duration
end
# start_time
result << start_time.hours.to_s.rjust(2, '0')
result << ':' << start_time.minutes.to_s.rjust(2, '0')
result << ':' << start_time.seconds.to_s.rjust(2, '0')
result << '.' << start_time.milliseconds.to_s.rjust(3, '0')
result << " --> "
# end_time
result << end_time.hours.to_s.rjust(2, '0')
result << ':' << end_time.minutes.to_s.rjust(2, '0')
result << ':' << end_time.seconds.to_s.rjust(2, '0')
result << '.' << end_time.milliseconds.to_s.rjust(3, '0')
result << "\n"
node.children.each do |s|
result << s.content
text = String.build do |io|
node.children.each do |s|
io << s.content
end
end
result << "\n"
result << "\n"
vtt.cue(start_time, end_time, text)
end
end
return result
end
end

40
src/invidious/videos/transcript.cr
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@ -34,41 +34,15 @@ module Invidious::Videos
# Convert into array of TranscriptLine
lines = self.parse(initial_data)
settings_field = {
"Kind" => "captions",
"Language" => target_language,
}
# Taken from Invidious::Videos::Captions::Metadata.timedtext_to_vtt()
vtt = String.build do |vtt|
vtt << <<-END_VTT
WEBVTT
Kind: captions
Language: #{target_language}
END_VTT
vtt << "\n\n"
vtt = WebVTT.build(settings_field) do |vtt|
lines.each do |line|
start_time = line.start_ms
end_time = line.end_ms
# start_time
vtt << start_time.hours.to_s.rjust(2, '0')
vtt << ':' << start_time.minutes.to_s.rjust(2, '0')
vtt << ':' << start_time.seconds.to_s.rjust(2, '0')
vtt << '.' << start_time.milliseconds.to_s.rjust(3, '0')
vtt << " --> "
# end_time
vtt << end_time.hours.to_s.rjust(2, '0')
vtt << ':' << end_time.minutes.to_s.rjust(2, '0')
vtt << ':' << end_time.seconds.to_s.rjust(2, '0')
vtt << '.' << end_time.milliseconds.to_s.rjust(3, '0')
vtt << "\n"
vtt << line.line
vtt << "\n"
vtt << "\n"
vtt.cue(line.start_ms, line.end_ms, line.line)
end
end