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yt-dlp/yt_dlp/downloader/fragment.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

432 lines
18 KiB
Python

from __future__ import division, unicode_literals
import os
import time
import json
try:
from Crypto.Cipher import AES
can_decrypt_frag = True
except ImportError:
can_decrypt_frag = False
try:
import concurrent.futures
can_threaded_download = True
except ImportError:
can_threaded_download = False
from .common import FileDownloader
from .http import HttpFD
from ..compat import (
compat_urllib_error,
compat_struct_pack,
)
from ..utils import (
DownloadError,
error_to_compat_str,
encodeFilename,
sanitize_open,
sanitized_Request,
)
class HttpQuietDownloader(HttpFD):
def to_screen(self, *args, **kargs):
pass
class FragmentFD(FileDownloader):
"""
A base file downloader class for fragmented media (e.g. f4m/m3u8 manifests).
Available options:
fragment_retries: Number of times to retry a fragment for HTTP error (DASH
and hlsnative only)
skip_unavailable_fragments:
Skip unavailable fragments (DASH and hlsnative only)
keep_fragments: Keep downloaded fragments on disk after downloading is
finished
_no_ytdl_file: Don't use .ytdl file
For each incomplete fragment download yt-dlp keeps on disk a special
bookkeeping file with download state and metadata (in future such files will
be used for any incomplete download handled by yt-dlp). This file is
used to properly handle resuming, check download file consistency and detect
potential errors. The file has a .ytdl extension and represents a standard
JSON file of the following format:
extractor:
Dictionary of extractor related data. TBD.
downloader:
Dictionary of downloader related data. May contain following data:
current_fragment:
Dictionary with current (being downloaded) fragment data:
index: 0-based index of current fragment among all fragments
fragment_count:
Total count of fragments
This feature is experimental and file format may change in future.
"""
def report_retry_fragment(self, err, frag_index, count, retries):
self.to_screen(
'\r[download] Got server HTTP error: %s. Retrying fragment %d (attempt %d of %s) ...'
% (error_to_compat_str(err), frag_index, count, self.format_retries(retries)))
def report_skip_fragment(self, frag_index):
self.to_screen('[download] Skipping fragment %d ...' % frag_index)
def _prepare_url(self, info_dict, url):
headers = info_dict.get('http_headers')
return sanitized_Request(url, None, headers) if headers else url
def _prepare_and_start_frag_download(self, ctx, info_dict):
self._prepare_frag_download(ctx)
self._start_frag_download(ctx, info_dict)
def __do_ytdl_file(self, ctx):
return not ctx['live'] and not ctx['tmpfilename'] == '-' and not self.params.get('_no_ytdl_file')
def _read_ytdl_file(self, ctx):
assert 'ytdl_corrupt' not in ctx
stream, _ = sanitize_open(self.ytdl_filename(ctx['filename']), 'r')
try:
ytdl_data = json.loads(stream.read())
ctx['fragment_index'] = ytdl_data['downloader']['current_fragment']['index']
if 'extra_state' in ytdl_data['downloader']:
ctx['extra_state'] = ytdl_data['downloader']['extra_state']
except Exception:
ctx['ytdl_corrupt'] = True
finally:
stream.close()
def _write_ytdl_file(self, ctx):
frag_index_stream, _ = sanitize_open(self.ytdl_filename(ctx['filename']), 'w')
try:
downloader = {
'current_fragment': {
'index': ctx['fragment_index'],
},
}
if 'extra_state' in ctx:
downloader['extra_state'] = ctx['extra_state']
if ctx.get('fragment_count') is not None:
downloader['fragment_count'] = ctx['fragment_count']
frag_index_stream.write(json.dumps({'downloader': downloader}))
finally:
frag_index_stream.close()
def _download_fragment(self, ctx, frag_url, info_dict, headers=None, request_data=None):
fragment_filename = '%s-Frag%d' % (ctx['tmpfilename'], ctx['fragment_index'])
fragment_info_dict = {
'url': frag_url,
'http_headers': headers or info_dict.get('http_headers'),
'request_data': request_data,
}
success = ctx['dl'].download(fragment_filename, fragment_info_dict)
if not success:
return False, None
if fragment_info_dict.get('filetime'):
ctx['fragment_filetime'] = fragment_info_dict.get('filetime')
ctx['fragment_filename_sanitized'] = fragment_filename
return True, self._read_fragment(ctx)
def _read_fragment(self, ctx):
down, frag_sanitized = sanitize_open(ctx['fragment_filename_sanitized'], 'rb')
ctx['fragment_filename_sanitized'] = frag_sanitized
frag_content = down.read()
down.close()
return frag_content
def _append_fragment(self, ctx, frag_content):
try:
ctx['dest_stream'].write(frag_content)
ctx['dest_stream'].flush()
finally:
if self.__do_ytdl_file(ctx):
self._write_ytdl_file(ctx)
if not self.params.get('keep_fragments', False):
os.remove(encodeFilename(ctx['fragment_filename_sanitized']))
del ctx['fragment_filename_sanitized']
def _prepare_frag_download(self, ctx):
if 'live' not in ctx:
ctx['live'] = False
if not ctx['live']:
total_frags_str = '%d' % ctx['total_frags']
ad_frags = ctx.get('ad_frags', 0)
if ad_frags:
total_frags_str += ' (not including %d ad)' % ad_frags
else:
total_frags_str = 'unknown (live)'
self.to_screen(
'[%s] Total fragments: %s' % (self.FD_NAME, total_frags_str))
self.report_destination(ctx['filename'])
dl = HttpQuietDownloader(
self.ydl,
{
'continuedl': True,
'quiet': True,
'noprogress': True,
'ratelimit': self.params.get('ratelimit'),
'retries': self.params.get('retries', 0),
'nopart': self.params.get('nopart', False),
'test': self.params.get('test', False),
}
)
tmpfilename = self.temp_name(ctx['filename'])
open_mode = 'wb'
resume_len = 0
# Establish possible resume length
if os.path.isfile(encodeFilename(tmpfilename)):
open_mode = 'ab'
resume_len = os.path.getsize(encodeFilename(tmpfilename))
# Should be initialized before ytdl file check
ctx.update({
'tmpfilename': tmpfilename,
'fragment_index': 0,
})
if self.__do_ytdl_file(ctx):
if os.path.isfile(encodeFilename(self.ytdl_filename(ctx['filename']))):
self._read_ytdl_file(ctx)
is_corrupt = ctx.get('ytdl_corrupt') is True
is_inconsistent = ctx['fragment_index'] > 0 and resume_len == 0
if is_corrupt or is_inconsistent:
message = (
'.ytdl file is corrupt' if is_corrupt else
'Inconsistent state of incomplete fragment download')
self.report_warning(
'%s. Restarting from the beginning ...' % message)
ctx['fragment_index'] = resume_len = 0
if 'ytdl_corrupt' in ctx:
del ctx['ytdl_corrupt']
self._write_ytdl_file(ctx)
else:
self._write_ytdl_file(ctx)
assert ctx['fragment_index'] == 0
dest_stream, tmpfilename = sanitize_open(tmpfilename, open_mode)
ctx.update({
'dl': dl,
'dest_stream': dest_stream,
'tmpfilename': tmpfilename,
# Total complete fragments downloaded so far in bytes
'complete_frags_downloaded_bytes': resume_len,
})
def _start_frag_download(self, ctx, info_dict):
resume_len = ctx['complete_frags_downloaded_bytes']
total_frags = ctx['total_frags']
# This dict stores the download progress, it's updated by the progress
# hook
state = {
'status': 'downloading',
'downloaded_bytes': resume_len,
'fragment_index': ctx['fragment_index'],
'fragment_count': total_frags,
'filename': ctx['filename'],
'tmpfilename': ctx['tmpfilename'],
}
start = time.time()
ctx.update({
'started': start,
# Amount of fragment's bytes downloaded by the time of the previous
# frag progress hook invocation
'prev_frag_downloaded_bytes': 0,
})
def frag_progress_hook(s):
if s['status'] not in ('downloading', 'finished'):
return
time_now = time.time()
state['elapsed'] = time_now - start
frag_total_bytes = s.get('total_bytes') or 0
s['fragment_info_dict'] = s.pop('info_dict', {})
if not ctx['live']:
estimated_size = (
(ctx['complete_frags_downloaded_bytes'] + frag_total_bytes)
/ (state['fragment_index'] + 1) * total_frags)
state['total_bytes_estimate'] = estimated_size
if s['status'] == 'finished':
state['fragment_index'] += 1
ctx['fragment_index'] = state['fragment_index']
state['downloaded_bytes'] += frag_total_bytes - ctx['prev_frag_downloaded_bytes']
ctx['complete_frags_downloaded_bytes'] = state['downloaded_bytes']
ctx['prev_frag_downloaded_bytes'] = 0
else:
frag_downloaded_bytes = s['downloaded_bytes']
state['downloaded_bytes'] += frag_downloaded_bytes - ctx['prev_frag_downloaded_bytes']
if not ctx['live']:
state['eta'] = self.calc_eta(
start, time_now, estimated_size - resume_len,
state['downloaded_bytes'] - resume_len)
state['speed'] = s.get('speed') or ctx.get('speed')
ctx['speed'] = state['speed']
ctx['prev_frag_downloaded_bytes'] = frag_downloaded_bytes
self._hook_progress(state, info_dict)
ctx['dl'].add_progress_hook(frag_progress_hook)
return start
def _finish_frag_download(self, ctx, info_dict):
ctx['dest_stream'].close()
if self.__do_ytdl_file(ctx):
ytdl_filename = encodeFilename(self.ytdl_filename(ctx['filename']))
if os.path.isfile(ytdl_filename):
os.remove(ytdl_filename)
elapsed = time.time() - ctx['started']
if ctx['tmpfilename'] == '-':
downloaded_bytes = ctx['complete_frags_downloaded_bytes']
else:
self.try_rename(ctx['tmpfilename'], ctx['filename'])
if self.params.get('updatetime', True):
filetime = ctx.get('fragment_filetime')
if filetime:
try:
os.utime(ctx['filename'], (time.time(), filetime))
except Exception:
pass
downloaded_bytes = os.path.getsize(encodeFilename(ctx['filename']))
self._hook_progress({
'downloaded_bytes': downloaded_bytes,
'total_bytes': downloaded_bytes,
'filename': ctx['filename'],
'status': 'finished',
'elapsed': elapsed,
}, info_dict)
def _prepare_external_frag_download(self, ctx):
if 'live' not in ctx:
ctx['live'] = False
if not ctx['live']:
total_frags_str = '%d' % ctx['total_frags']
ad_frags = ctx.get('ad_frags', 0)
if ad_frags:
total_frags_str += ' (not including %d ad)' % ad_frags
else:
total_frags_str = 'unknown (live)'
self.to_screen(
'[%s] Total fragments: %s' % (self.FD_NAME, total_frags_str))
tmpfilename = self.temp_name(ctx['filename'])
# Should be initialized before ytdl file check
ctx.update({
'tmpfilename': tmpfilename,
'fragment_index': 0,
})
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:
pack_func = lambda frag_content, _: frag_content
def download_fragment(fragment, ctx):
frag_index = ctx['fragment_index'] = fragment['frag_index']
headers = info_dict.get('http_headers', {})
byte_range = fragment.get('byte_range')
if byte_range:
headers['Range'] = 'bytes=%d-%d' % (byte_range['start'], byte_range['end'] - 1)
# Never skip the first fragment
fatal = is_fatal(fragment.get('index') or (frag_index - 1))
count, frag_content = 0, None
while count <= fragment_retries:
try:
success, frag_content = self._download_fragment(ctx, fragment['url'], info_dict, headers)
if not success:
return False, frag_index
break
except compat_urllib_error.HTTPError as err:
# Unavailable (possibly temporary) fragments may be served.
# First we try to retry then either skip or abort.
# See https://github.com/ytdl-org/youtube-dl/issues/10165,
# https://github.com/ytdl-org/youtube-dl/issues/10448).
count += 1
if count <= fragment_retries:
self.report_retry_fragment(err, frag_index, count, fragment_retries)
except DownloadError:
# Don't retry fragment if error occurred during HTTP downloading
# itself since it has own retry settings
if not fatal:
break
raise
if count > fragment_retries:
if not fatal:
return False, frag_index
ctx['dest_stream'].close()
self.report_error('Giving up after %s fragment retries' % fragment_retries)
return False, frag_index
return frag_content, frag_index
def decrypt_fragment(fragment, frag_content):
decrypt_info = fragment.get('decrypt_info')
if not decrypt_info or decrypt_info['METHOD'] != 'AES-128':
return frag_content
iv = decrypt_info.get('IV') or compat_struct_pack('>8xq', fragment['media_sequence'])
decrypt_info['KEY'] = decrypt_info.get('KEY') or self.ydl.urlopen(
self._prepare_url(info_dict, info_dict.get('_decryption_key_url') or decrypt_info['URI'])).read()
# Don't decrypt the content in tests since the data is explicitly truncated and it's not to a valid block
# size (see https://github.com/ytdl-org/youtube-dl/pull/27660). Tests only care that the correct data downloaded,
# not what it decrypts to.
if self.params.get('test', False):
return frag_content
return AES.new(decrypt_info['KEY'], AES.MODE_CBC, iv).decrypt(frag_content)
def append_fragment(frag_content, frag_index, ctx):
if not frag_content:
if not is_fatal(frag_index - 1):
self.report_skip_fragment(frag_index)
return True
else:
ctx['dest_stream'].close()
self.report_error(
'fragment %s not found, unable to continue' % frag_index)
return False
self._append_fragment(ctx, pack_func(frag_content, frag_index))
return True
max_workers = self.params.get('concurrent_fragment_downloads', 1)
if can_threaded_download and max_workers > 1:
def _download_fragment(fragment):
ctx_copy = ctx.copy()
frag_content, frag_index = download_fragment(fragment, ctx_copy)
return fragment, frag_content, frag_index, ctx_copy.get('fragment_filename_sanitized')
self.report_warning('The download speed shown is only of one thread. This is a known issue and patches are welcome')
with concurrent.futures.ThreadPoolExecutor(max_workers) as pool:
for fragment, frag_content, frag_index, frag_filename in pool.map(_download_fragment, fragments):
ctx['fragment_filename_sanitized'] = frag_filename
ctx['fragment_index'] = frag_index
result = append_fragment(decrypt_fragment(fragment, frag_content), frag_index, ctx)
if not result:
return False
else:
for fragment in fragments:
frag_content, frag_index = download_fragment(fragment, ctx)
result = append_fragment(decrypt_fragment(fragment, frag_content), frag_index, ctx)
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