1 files changed, 103 insertions, 0 deletions
diff --git a/yt_dlp/downloader/dash.py b/yt_dlp/downloader/dash.py
new file mode 100644
index 000000000..d758282c1
--- /dev/null
+++ b/yt_dlp/downloader/dash.py
@@ -0,0 +1,103 @@
+from __future__ import unicode_literals
+
+from ..downloader import _get_real_downloader
+from .fragment import FragmentFD
+
+from ..compat import compat_urllib_error
+from ..utils import (
+    DownloadError,
+    urljoin,
+)
+
+
+class DashSegmentsFD(FragmentFD):
+    """
+    Download segments in a DASH manifest
+    """
+
+    FD_NAME = 'dashsegments'
+
+    def real_download(self, filename, info_dict):
+        fragment_base_url = info_dict.get('fragment_base_url')
+        fragments = info_dict['fragments'][:1] if self.params.get(
+            'test', False) else info_dict['fragments']
+
+        real_downloader = _get_real_downloader(info_dict, 'frag_urls', self.params, None)
+
+        ctx = {
+            'filename': filename,
+            'total_frags': len(fragments),
+        }
+
+        if real_downloader:
+            self._prepare_external_frag_download(ctx)
+        else:
+            self._prepare_and_start_frag_download(ctx)
+
+        fragment_retries = self.params.get('fragment_retries', 0)
+        skip_unavailable_fragments = self.params.get('skip_unavailable_fragments', True)
+
+        fragment_urls = []
+        frag_index = 0
+        for i, fragment in enumerate(fragments):
+            frag_index += 1
+            if frag_index <= ctx['fragment_index']:
+                continue
+            fragment_url = fragment.get('url')
+            if not fragment_url:
+                assert fragment_base_url
+                fragment_url = urljoin(fragment_base_url, fragment['path'])
+
+            if real_downloader:
+                fragment_urls.append(fragment_url)
+                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:
+                    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 attempts
+                    # 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
+
+            if count > fragment_retries:
+                if not fatal:
+                    self.report_skip_fragment(frag_index)
+                    continue
+                self.report_error('giving up after %s fragment retries' % fragment_retries)
+                return False
+
+        if real_downloader:
+            info_copy = info_dict.copy()
+            info_copy['url_list'] = fragment_urls
+            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)
+            success = fd.real_download(filename, info_copy)
+            if not success:
+                return False
+        else:
+            self._finish_frag_download(ctx)
+        return True