From 0224162ad22dc19d58a73202d796eb3e99f0a71c Mon Sep 17 00:00:00 2001 From: syeopite Date: Tue, 11 Jun 2024 17:57:33 -0700 Subject: [PATCH] Rewrite transcript logic to be more generic The transcript logic in Invidious was written specifically as a workaround for captions, and not transcripts as a feature. This commit genericises the logic a bit as so it can be used for implementing transcripts within Invidious' API and UI as well. The most notable change is the added parsing of section headings when it was previously skipped over in favor of regular lines. --- src/invidious/routes/api/v1/videos.cr | 9 ++- src/invidious/videos/transcript.cr | 90 +++++++++++++++++---------- 2 files changed, 63 insertions(+), 36 deletions(-) diff --git a/src/invidious/routes/api/v1/videos.cr b/src/invidious/routes/api/v1/videos.cr index 9281f4dd..faff2f59 100644 --- a/src/invidious/routes/api/v1/videos.cr +++ b/src/invidious/routes/api/v1/videos.cr @@ -89,9 +89,14 @@ module Invidious::Routes::API::V1::Videos if CONFIG.use_innertube_for_captions params = Invidious::Videos::Transcript.generate_param(id, caption.language_code, caption.auto_generated) - initial_data = YoutubeAPI.get_transcript(params) - webvtt = Invidious::Videos::Transcript.convert_transcripts_to_vtt(initial_data, caption.language_code) + transcript = Invidious::Videos::Transcript.from_raw( + YoutubeAPI.get_transcript(params), + caption.language_code, + caption.auto_generated + ) + + webvtt = transcript.to_vtt else # Timedtext API handling url = URI.parse("#{caption.base_url}&tlang=#{tlang}").request_target diff --git a/src/invidious/videos/transcript.cr b/src/invidious/videos/transcript.cr index dac00eea..42f29f46 100644 --- a/src/invidious/videos/transcript.cr +++ b/src/invidious/videos/transcript.cr @@ -1,8 +1,21 @@ module Invidious::Videos - # Namespace for methods primarily relating to Transcripts - module Transcript - record TranscriptLine, start_ms : Time::Span, end_ms : Time::Span, line : String + # A `Transcripts` struct encapsulates a sequence of lines that together forms the whole transcript for a given YouTube video. + # These lines can be categorized into two types: section headings and regular lines representing content from the video. + struct Transcript + # Types + record HeadingLine, start_ms : Time::Span, end_ms : Time::Span, line : String + record RegularLine, start_ms : Time::Span, end_ms : Time::Span, line : String + alias TranscriptLine = HeadingLine | RegularLine + property lines : Array(TranscriptLine) + property language_code : String + property auto_generated : Bool + + # Initializes a new Transcript struct with the contents and associated metadata describing it + def initialize(@lines : Array(TranscriptLine), @language_code : String, @auto_generated : Bool) + end + + # Generates a protobuf string to fetch the requested transcript from YouTube def self.generate_param(video_id : String, language_code : String, auto_generated : Bool) : String kind = auto_generated ? "asr" : "" @@ -30,48 +43,57 @@ module Invidious::Videos return params end - def self.convert_transcripts_to_vtt(initial_data : Hash(String, JSON::Any), target_language : String) : String - # Convert into array of TranscriptLine - lines = self.parse(initial_data) + # Constructs a Transcripts struct from the initial YouTube response + def self.from_raw(initial_data : Hash(String, JSON::Any), language_code : String, auto_generated : Bool) + body = initial_data.dig("actions", 0, "updateEngagementPanelAction", "content", "transcriptRenderer", + "content", "transcriptSearchPanelRenderer", "body", "transcriptSegmentListRenderer", + "initialSegments").as_a + lines = [] of TranscriptLine + + body.each do |line| + if unpacked_line = line["transcriptSectionHeaderRenderer"]? + line_type = HeadingLine + else + unpacked_line = line["transcriptSegmentRenderer"] + line_type = RegularLine + end + + start_ms = unpacked_line["startMs"].as_s.to_i.millisecond + end_ms = unpacked_line["endMs"].as_s.to_i.millisecond + text = extract_text(unpacked_line["snippet"]) || "" + + lines << line_type.new(start_ms, end_ms, text) + end + + return Transcript.new( + lines: lines, + language_code: language_code, + auto_generated: auto_generated, + ) + end + + # Converts transcript lines to a WebVTT file + # + # This is used within Invidious to replace subtitles + # as to workaround YouTube's rate-limited timedtext endpoint. + def to_vtt settings_field = { "Kind" => "captions", - "Language" => target_language, + "Language" => @language_code, } - # Taken from Invidious::Videos::Captions::Metadata.timedtext_to_vtt() vtt = WebVTT.build(settings_field) do |vtt| - lines.each do |line| + @lines.each do |line| + # Section headers are excluded from the VTT conversion as to + # match the regular captions returned from YouTube as much as possible + next if line.is_a? HeadingLine + vtt.cue(line.start_ms, line.end_ms, line.line) end end return vtt end - - private def self.parse(initial_data : Hash(String, JSON::Any)) - body = initial_data.dig("actions", 0, "updateEngagementPanelAction", "content", "transcriptRenderer", - "content", "transcriptSearchPanelRenderer", "body", "transcriptSegmentListRenderer", - "initialSegments").as_a - - lines = [] of TranscriptLine - body.each do |line| - # Transcript section headers. They are not apart of the captions and as such we can safely skip them. - if line.as_h.has_key?("transcriptSectionHeaderRenderer") - next - end - - line = line["transcriptSegmentRenderer"] - - start_ms = line["startMs"].as_s.to_i.millisecond - end_ms = line["endMs"].as_s.to_i.millisecond - - text = extract_text(line["snippet"]) || "" - - lines << TranscriptLine.new(start_ms, end_ms, text) - end - - return lines - end end end