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yt-dlp/yt_dlp/downloader/hls.py
Felix S 25a3f4f5d6
[webvtt] Merge daisy-chained duplicate cues (#638) 
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
2021-08-10 01:52:30 +05:30

342 lines
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Python
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from __future__ import unicode_literals
import re
import io
import binascii
from ..downloader import get_suitable_downloader
from .fragment import FragmentFD, can_decrypt_frag
from .external import FFmpegFD
from ..compat import (
compat_urlparse,
)
from ..utils import (
parse_m3u8_attributes,
update_url_query,
bug_reports_message,
)
from .. import webvtt
class HlsFD(FragmentFD):
"""
Download segments in a m3u8 manifest. External downloaders can take over
the fragment downloads by supporting the 'm3u8_frag_urls' protocol and
re-defining 'supports_manifest' function
"""
FD_NAME = 'hlsnative'
@staticmethod
def can_download(manifest, info_dict, allow_unplayable_formats=False, with_crypto=can_decrypt_frag):
UNSUPPORTED_FEATURES = [
# r'#EXT-X-BYTERANGE', # playlists composed of byte ranges of media files [2]
# Live streams heuristic does not always work (e.g. geo restricted to Germany
# http://hls-geo.daserste.de/i/videoportal/Film/c_620000/622873/format,716451,716457,716450,716458,716459,.mp4.csmil/index_4_av.m3u8?null=0)
# r'#EXT-X-MEDIA-SEQUENCE:(?!0$)', # live streams [3]
# This heuristic also is not correct since segments may not be appended as well.
# Twitch vods of finished streams have EXT-X-PLAYLIST-TYPE:EVENT despite
# no segments will definitely be appended to the end of the playlist.
# r'#EXT-X-PLAYLIST-TYPE:EVENT', # media segments may be appended to the end of
# # event media playlists [4]
# r'#EXT-X-MAP:', # media initialization [5]
# 1. https://tools.ietf.org/html/draft-pantos-http-live-streaming-17#section-4.3.2.4
# 2. https://tools.ietf.org/html/draft-pantos-http-live-streaming-17#section-4.3.2.2
# 3. https://tools.ietf.org/html/draft-pantos-http-live-streaming-17#section-4.3.3.2
# 4. https://tools.ietf.org/html/draft-pantos-http-live-streaming-17#section-4.3.3.5
# 5. https://tools.ietf.org/html/draft-pantos-http-live-streaming-17#section-4.3.2.5
]
if not allow_unplayable_formats:
UNSUPPORTED_FEATURES += [
r'#EXT-X-KEY:METHOD=(?!NONE|AES-128)', # encrypted streams [1]
]
def check_results():
yield not info_dict.get('is_live')
is_aes128_enc = '#EXT-X-KEY:METHOD=AES-128' in manifest
yield with_crypto or not is_aes128_enc
yield not (is_aes128_enc and r'#EXT-X-BYTERANGE' in manifest)
for feature in UNSUPPORTED_FEATURES:
yield not re.search(feature, manifest)
return all(check_results())
def real_download(self, filename, info_dict):
man_url = info_dict['url']
self.to_screen('[%s] Downloading m3u8 manifest' % self.FD_NAME)
urlh = self.ydl.urlopen(self._prepare_url(info_dict, man_url))
man_url = urlh.geturl()
s = urlh.read().decode('utf-8', 'ignore')
if not self.can_download(s, info_dict, self.params.get('allow_unplayable_formats')):
if info_dict.get('extra_param_to_segment_url') or info_dict.get('_decryption_key_url'):
self.report_error('pycryptodome not found. Please install')
return False
if self.can_download(s, info_dict, with_crypto=True):
self.report_warning('pycryptodome is needed to download this file natively')
fd = FFmpegFD(self.ydl, self.params)
self.report_warning(
'%s detected unsupported features; extraction will be delegated to %s' % (self.FD_NAME, fd.get_basename()))
return fd.real_download(filename, info_dict)
is_webvtt = info_dict['ext'] == 'vtt'
if is_webvtt:
real_downloader = None # Packing the fragments is not currently supported for external downloader
else:
real_downloader = get_suitable_downloader(
info_dict, self.params, None, protocol='m3u8_frag_urls', to_stdout=(filename == '-'))
if real_downloader and not real_downloader.supports_manifest(s):
real_downloader = None
if real_downloader:
self.to_screen(
'[%s] Fragment downloads will be delegated to %s' % (self.FD_NAME, real_downloader.get_basename()))
def is_ad_fragment_start(s):
return (s.startswith('#ANVATO-SEGMENT-INFO') and 'type=ad' in s
or s.startswith('#UPLYNK-SEGMENT') and s.endswith(',ad'))
def is_ad_fragment_end(s):
return (s.startswith('#ANVATO-SEGMENT-INFO') and 'type=master' in s
or s.startswith('#UPLYNK-SEGMENT') and s.endswith(',segment'))
fragments = []
media_frags = 0
ad_frags = 0
ad_frag_next = False
for line in s.splitlines():
line = line.strip()
if not line:
continue
if line.startswith('#'):
if is_ad_fragment_start(line):
ad_frag_next = True
elif is_ad_fragment_end(line):
ad_frag_next = False
continue
if ad_frag_next:
ad_frags += 1
continue
media_frags += 1
ctx = {
'filename': filename,
'total_frags': media_frags,
'ad_frags': ad_frags,
}
if real_downloader:
self._prepare_external_frag_download(ctx)
else:
self._prepare_and_start_frag_download(ctx, info_dict)
extra_state = ctx.setdefault('extra_state', {})
format_index = info_dict.get('format_index')
extra_query = None
extra_param_to_segment_url = info_dict.get('extra_param_to_segment_url')
if extra_param_to_segment_url:
extra_query = compat_urlparse.parse_qs(extra_param_to_segment_url)
i = 0
media_sequence = 0
decrypt_info = {'METHOD': 'NONE'}
byte_range = {}
discontinuity_count = 0
frag_index = 0
ad_frag_next = False
for line in s.splitlines():
line = line.strip()
if line:
if not line.startswith('#'):
if format_index and discontinuity_count != format_index:
continue
if ad_frag_next:
continue
frag_index += 1
if frag_index <= ctx['fragment_index']:
continue
frag_url = (
line
if re.match(r'^https?://', line)
else compat_urlparse.urljoin(man_url, line))
if extra_query:
frag_url = update_url_query(frag_url, extra_query)
fragments.append({
'frag_index': frag_index,
'url': frag_url,
'decrypt_info': decrypt_info,
'byte_range': byte_range,
'media_sequence': media_sequence,
})
elif line.startswith('#EXT-X-MAP'):
if format_index and discontinuity_count != format_index:
continue
if frag_index > 0:
self.report_error(
'Initialization fragment found after media fragments, unable to download')
return False
frag_index += 1
map_info = parse_m3u8_attributes(line[11:])
frag_url = (
map_info.get('URI')
if re.match(r'^https?://', map_info.get('URI'))
else compat_urlparse.urljoin(man_url, map_info.get('URI')))
if extra_query:
frag_url = update_url_query(frag_url, extra_query)
fragments.append({
'frag_index': frag_index,
'url': frag_url,
'decrypt_info': decrypt_info,
'byte_range': byte_range,
'media_sequence': media_sequence
})
if map_info.get('BYTERANGE'):
splitted_byte_range = map_info.get('BYTERANGE').split('@')
sub_range_start = int(splitted_byte_range[1]) if len(splitted_byte_range) == 2 else byte_range['end']
byte_range = {
'start': sub_range_start,
'end': sub_range_start + int(splitted_byte_range[0]),
}
elif line.startswith('#EXT-X-KEY'):
decrypt_url = decrypt_info.get('URI')
decrypt_info = parse_m3u8_attributes(line[11:])
if decrypt_info['METHOD'] == 'AES-128':
if 'IV' in decrypt_info:
decrypt_info['IV'] = binascii.unhexlify(decrypt_info['IV'][2:].zfill(32))
if not re.match(r'^https?://', decrypt_info['URI']):
decrypt_info['URI'] = compat_urlparse.urljoin(
man_url, decrypt_info['URI'])
if extra_query:
decrypt_info['URI'] = update_url_query(decrypt_info['URI'], extra_query)
if decrypt_url != decrypt_info['URI']:
decrypt_info['KEY'] = None
elif line.startswith('#EXT-X-MEDIA-SEQUENCE'):
media_sequence = int(line[22:])
elif line.startswith('#EXT-X-BYTERANGE'):
splitted_byte_range = line[17:].split('@')
sub_range_start = int(splitted_byte_range[1]) if len(splitted_byte_range) == 2 else byte_range['end']
byte_range = {
'start': sub_range_start,
'end': sub_range_start + int(splitted_byte_range[0]),
}
elif is_ad_fragment_start(line):
ad_frag_next = True
elif is_ad_fragment_end(line):
ad_frag_next = False
elif line.startswith('#EXT-X-DISCONTINUITY'):
discontinuity_count += 1
i += 1
media_sequence += 1
# We only download the first fragment during the test
if self.params.get('test', False):
fragments = [fragments[0] if fragments else None]
if real_downloader:
info_copy = info_dict.copy()
info_copy['fragments'] = fragments
fd = real_downloader(self.ydl, self.params)
# TODO: Make progress updates work without hooking twice
# for ph in self._progress_hooks:
# fd.add_progress_hook(ph)
return fd.real_download(filename, info_copy)
if is_webvtt:
def pack_fragment(frag_content, frag_index):
output = io.StringIO()
adjust = 0
for block in webvtt.parse_fragment(frag_content):
if isinstance(block, webvtt.CueBlock):
block.start += adjust
block.end += adjust
dedup_window = extra_state.setdefault('webvtt_dedup_window', [])
ready = []
i = 0
is_new = True
while i < len(dedup_window):
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]
if is_new:
dedup_window.append(block.as_json)
for block in ready:
block.write_into(output)
# 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:
block.mpegts = 0
extra_state.setdefault('webvtt_mpegts_adjust', 0)
block.mpegts += extra_state['webvtt_mpegts_adjust'] << 33
if block.mpegts < extra_state.get('webvtt_mpegts_last', 0):
extra_state['webvtt_mpegts_adjust'] += 1
block.mpegts += 1 << 33
extra_state['webvtt_mpegts_last'] = block.mpegts
if frag_index == 1:
extra_state['webvtt_mpegts'] = block.mpegts or 0
extra_state['webvtt_local'] = block.local or 0
# XXX: block.local = block.mpegts = None ?
else:
if block.mpegts is not None and block.local is not None:
adjust = (
(block.mpegts - extra_state.get('webvtt_mpegts', 0))
- (block.local - extra_state.get('webvtt_local', 0))
)
continue
elif isinstance(block, webvtt.HeaderBlock):
if frag_index != 1:
# XXX: this should probably be silent as well
# or verify that all segments contain the same data
self.report_warning(bug_reports_message(
'Discarding a %s block found in the middle of the stream; '
'if the subtitles display incorrectly,'
% (type(block).__name__)))
continue
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:
return self.download_and_append_fragments(ctx, fragments, info_dict)
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