youtube_dl/downloader/dash.py

   1 from __future__ import unicode_literals
   2
   3 from .fragment import FragmentFD
   4 from ..compat import compat_urllib_error
   5 from ..utils import (
   6     DownloadError,
   7     urljoin,
   8 )
   9
  10
  11 class DashSegmentsFD(FragmentFD):
  12     """
  13     Download segments in a DASH manifest
  14     """
  15
  16     FD_NAME = 'dashsegments'
  17
  18     def real_download(self, filename, info_dict):
  19         fragment_base_url = info_dict.get('fragment_base_url')
  20         fragments = info_dict['fragments'][:1] if self.params.get(
  21             'test', False) else info_dict['fragments']
  22
  23         ctx = {
  24             'filename': filename,
  25             'total_frags': len(fragments),
  26         }
  27
  28         self._prepare_and_start_frag_download(ctx)
  29
  30         fragment_retries = self.params.get('fragment_retries', 0)
  31         skip_unavailable_fragments = self.params.get('skip_unavailable_fragments', True)
  32
  33         frag_index = 0
  34         for i, fragment in enumerate(fragments):
  35             frag_index += 1
  36             if frag_index <= ctx['fragment_index']:
  37                 continue
  38             # In DASH, the first segment contains necessary headers to
  39             # generate a valid MP4 file, so always abort for the first segment
  40             fatal = i == 0 or not skip_unavailable_fragments
  41             count = 0
  42             while count <= fragment_retries:
  43                 try:
  44                     fragment_url = fragment.get('url')
  45                     if not fragment_url:
  46                         assert fragment_base_url
  47                         fragment_url = urljoin(fragment_base_url, fragment['path'])
  48                     success, frag_content = self._download_fragment(ctx, fragment_url, info_dict)
  49                     if not success:
  50                         return False
  51                     self._append_fragment(ctx, frag_content)
  52                     break
  53                 except compat_urllib_error.HTTPError as err:
  54                     # YouTube may often return 404 HTTP error for a fragment causing the
  55                     # whole download to fail. However if the same fragment is immediately
  56                     # retried with the same request data this usually succeeds (1-2 attempts
  57                     # is usually enough) thus allowing to download the whole file successfully.
  58                     # To be future-proof we will retry all fragments that fail with any
  59                     # HTTP error.
  60                     count += 1
  61                     if count <= fragment_retries:
  62                         self.report_retry_fragment(err, frag_index, count, fragment_retries)
  63                 except DownloadError:
  64                     # Don't retry fragment if error occurred during HTTP downloading
  65                     # itself since it has own retry settings
  66                     if not fatal:
  67                         self.report_skip_fragment(frag_index)
  68                         break
  69                     raise
  70
  71             if count > fragment_retries:
  72                 if not fatal:
  73                     self.report_skip_fragment(frag_index)
  74                     continue
  75                 self.report_error('giving up after %s fragment retries' % fragment_retries)
  76                 return False
  77
  78         self._finish_frag_download(ctx)
  79
  80         return True