+ frag_index = 0
+ for i, fragment in enumerate(fragments):
+ frag_index += 1
+ if frag_index <= ctx['fragment_index']:
+ continue
+ # In DASH, the first segment contains necessary headers to
+ # generate a valid MP4 file, so always abort for the first segment
+ fatal = i == 0 or not skip_unavailable_fragments
+ count = 0
+ while count <= fragment_retries:
+ try:
+ fragment_url = fragment.get('url')
+ if not fragment_url:
+ assert fragment_base_url
+ fragment_url = urljoin(fragment_base_url, fragment['path'])
+ success, frag_content = self._download_fragment(ctx, fragment_url, info_dict)
+ if not success:
+ return False
+ self._append_fragment(ctx, frag_content)
+ break
+ except compat_urllib_error.HTTPError as err:
+ # YouTube may often return 404 HTTP error for a fragment causing the
+ # whole download to fail. However if the same fragment is immediately
+ # retried with the same request data this usually succeeds (1-2 attemps
+ # is usually enough) thus allowing to download the whole file successfully.
+ # To be future-proof we will retry all fragments that fail with any
+ # HTTP error.
+ 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:
+ self.report_skip_fragment(frag_index)
+ break
+ raise