1 files changed, 87 insertions, 0 deletions
diff --git a/yt_dlp/downloader/dash.py b/yt_dlp/downloader/dash.py
new file mode 100644
index 0000000..4328d73
--- /dev/null
+++ b/yt_dlp/downloader/dash.py
@@ -0,0 +1,87 @@
+import time
+import urllib.parse
+
+from . import get_suitable_downloader
+from .fragment import FragmentFD
+from ..utils import update_url_query, urljoin
+
+
+class DashSegmentsFD(FragmentFD):
+    """
+    Download segments in a DASH manifest. External downloaders can take over
+    the fragment downloads by supporting the 'dash_frag_urls' protocol
+    """
+
+    FD_NAME = 'dashsegments'
+
+    def real_download(self, filename, info_dict):
+        if info_dict.get('is_live') and set(info_dict['protocol'].split('+')) != {'http_dash_segments_generator'}:
+            self.report_error('Live DASH videos are not supported')
+
+        real_start = time.time()
+        real_downloader = get_suitable_downloader(
+            info_dict, self.params, None, protocol='dash_frag_urls', to_stdout=(filename == '-'))
+
+        requested_formats = [{**info_dict, **fmt} for fmt in info_dict.get('requested_formats', [])]
+        args = []
+        for fmt in requested_formats or [info_dict]:
+            try:
+                fragment_count = 1 if self.params.get('test') else len(fmt['fragments'])
+            except TypeError:
+                fragment_count = None
+            ctx = {
+                'filename': fmt.get('filepath') or filename,
+                'live': 'is_from_start' if fmt.get('is_from_start') else fmt.get('is_live'),
+                'total_frags': fragment_count,
+            }
+
+            if real_downloader:
+                self._prepare_external_frag_download(ctx)
+            else:
+                self._prepare_and_start_frag_download(ctx, fmt)
+            ctx['start'] = real_start
+
+            extra_query = None
+            extra_param_to_segment_url = info_dict.get('extra_param_to_segment_url')
+            if extra_param_to_segment_url:
+                extra_query = urllib.parse.parse_qs(extra_param_to_segment_url)
+
+            fragments_to_download = self._get_fragments(fmt, ctx, extra_query)
+
+            if real_downloader:
+                self.to_screen(
+                    f'[{self.FD_NAME}] Fragment downloads will be delegated to {real_downloader.get_basename()}')
+                info_dict['fragments'] = list(fragments_to_download)
+                fd = real_downloader(self.ydl, self.params)
+                return fd.real_download(filename, info_dict)
+
+            args.append([ctx, fragments_to_download, fmt])
+
+        return self.download_and_append_fragments_multiple(*args, is_fatal=lambda idx: idx == 0)
+
+    def _resolve_fragments(self, fragments, ctx):
+        fragments = fragments(ctx) if callable(fragments) else fragments
+        return [next(iter(fragments))] if self.params.get('test') else fragments
+
+    def _get_fragments(self, fmt, ctx, extra_query):
+        fragment_base_url = fmt.get('fragment_base_url')
+        fragments = self._resolve_fragments(fmt['fragments'], ctx)
+
+        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 extra_query:
+                fragment_url = update_url_query(fragment_url, extra_query)
+
+            yield {
+                'frag_index': frag_index,
+                'fragment_count': fragment.get('fragment_count'),
+                'index': i,
+                'url': fragment_url,
+            }