From 25a3f4f5d6de2bd5fb60cd11a46f0ac232882a56 Mon Sep 17 00:00:00 2001 From: Felix S Date: Mon, 9 Aug 2021 20:22:30 +0000 Subject: [PATCH] [webvtt] Merge daisy-chained duplicate cues (#638) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Fixes: https://github.com/yt-dlp/yt-dlp/issues/631#issuecomment-893338552 Previous deduplication algorithm only removed duplicate cues with identical text, styles and timestamps. This change also merges cues that come in ‘daisy chains’, where sequences of cues with identical text and styles appear in which the ending timestamp of one equals the starting timestamp of the next. This deduplication algorithm has the somewhat unfortunate side effect that NOTE blocks between cues, if found, will be emitted in a different order relative to their original cues. This may be unwanted if perfect fidelity is desired, but then so is daisy-chain deduplication itself. NOTE blocks ought to be ignored by WebVTT players in any case. Authored by: fstirlitz --- yt_dlp/downloader/fragment.py | 5 +++- yt_dlp/downloader/hls.py | 55 +++++++++++++++++++++++------------ yt_dlp/webvtt.py | 20 +++++++++++++ 3 files changed, 61 insertions(+), 19 deletions(-) diff --git a/yt_dlp/downloader/fragment.py b/yt_dlp/downloader/fragment.py index 1cc99a4e9..e3af140fd 100644 --- a/yt_dlp/downloader/fragment.py +++ b/yt_dlp/downloader/fragment.py @@ -329,7 +329,7 @@ def _prepare_external_frag_download(self, ctx): 'fragment_index': 0, }) - def download_and_append_fragments(self, ctx, fragments, info_dict, pack_func=None): + def download_and_append_fragments(self, ctx, fragments, info_dict, *, pack_func=None, finish_func=None): fragment_retries = self.params.get('fragment_retries', 0) is_fatal = (lambda idx: idx == 0) if self.params.get('skip_unavailable_fragments', True) else (lambda _: True) if not pack_func: @@ -424,5 +424,8 @@ def _download_fragment(fragment): if not result: return False + if finish_func is not None: + ctx['dest_stream'].write(finish_func()) + ctx['dest_stream'].flush() self._finish_frag_download(ctx, info_dict) return True diff --git a/yt_dlp/downloader/hls.py b/yt_dlp/downloader/hls.py index 9cbd5a584..9cfc191cb 100644 --- a/yt_dlp/downloader/hls.py +++ b/yt_dlp/downloader/hls.py @@ -260,29 +260,35 @@ def pack_fragment(frag_content, frag_index): block.end += adjust dedup_window = extra_state.setdefault('webvtt_dedup_window', []) - cue = block.as_json - # skip the cue if an identical one appears - # in the window of potential duplicates - # and prune the window of unviable candidates + ready = [] + i = 0 - skip = True + is_new = True while i < len(dedup_window): - window_cue = dedup_window[i] - if window_cue == cue: - break - if window_cue['end'] >= cue['start']: - i += 1 + wcue = dedup_window[i] + wblock = webvtt.CueBlock.from_json(wcue) + i += 1 + if wblock.hinges(block): + wcue['end'] = block.end + is_new = False continue + if wblock == block: + is_new = False + continue + if wblock.end > block.start: + continue + ready.append(wblock) + i -= 1 del dedup_window[i] - else: - skip = False - if skip: - continue + if is_new: + dedup_window.append(block.as_json) + for block in ready: + block.write_into(output) - # add the cue to the window - dedup_window.append(cue) + # we only emit cues once they fall out of the duplicate window + continue elif isinstance(block, webvtt.Magic): # take care of MPEG PES timestamp overflow if block.mpegts is None: @@ -317,6 +323,19 @@ def pack_fragment(frag_content, frag_index): block.write_into(output) return output.getvalue().encode('utf-8') + + def fin_fragments(): + dedup_window = extra_state.get('webvtt_dedup_window') + if not dedup_window: + return b'' + + output = io.StringIO() + for cue in dedup_window: + webvtt.CueBlock.from_json(cue).write_into(output) + + return output.getvalue().encode('utf-8') + + self.download_and_append_fragments( + ctx, fragments, info_dict, pack_func=pack_fragment, finish_func=fin_fragments) else: - pack_fragment = None - return self.download_and_append_fragments(ctx, fragments, info_dict, pack_fragment) + return self.download_and_append_fragments(ctx, fragments, info_dict) diff --git a/yt_dlp/webvtt.py b/yt_dlp/webvtt.py index ef55e6459..eee2a4a2d 100644 --- a/yt_dlp/webvtt.py +++ b/yt_dlp/webvtt.py @@ -331,6 +331,26 @@ def as_json(self): 'settings': self.settings, } + def __eq__(self, other): + return self.as_json == other.as_json + + @classmethod + def from_json(cls, json): + return cls( + id=json['id'], + start=json['start'], + end=json['end'], + text=json['text'], + settings=json['settings'] + ) + + def hinges(self, other): + if self.text != other.text: + return False + if self.settings != other.settings: + return False + return self.start <= self.end == other.start <= other.end + def parse_fragment(frag_content): """