add resolution parameter to playlist.download_all with helper function in StreamQuery

pytube/contrib/playlist.py

@@ -120,13 +120,12 @@ class Playlist:
         download_path: Optional[str] = None,
         prefix_number: bool = True,
         reverse_numbering: bool = False,
+        resolution:str = "720p"
     ) -> None:
         """Download all the videos in the the playlist. Initially, download
         resolution is 720p (or highest available), later more option
         should be added to download resolution of choice
 
-        TODO(nficano): Add option to download resolution of user's choice
-
         :param download_path:
             (optional) Output path for the playlist If one is not
             specified, defaults to the current working directory.
@@ -140,6 +139,9 @@ class Playlist:
             (optional) Lets you number playlists in reverse, since some
             playlists are ordered newest -> oldest.
         :type reverse_numbering: bool
+        :param resolution:
+            Video resolution i.e. "720p", "480p", "360p", "240p", "144p"
+        :type resolution: str
         """
 
         self.populate_video_urls()
@@ -156,14 +158,8 @@ class Playlist:
                 if not self.suppress_exception:
                     raise e
             else:
-                # TODO: this should not be hardcoded to a single user's
-                # preference
-                dl_stream = (
-                    yt.streams.filter(progressive=True, subtype="mp4",)
-                    .order_by("resolution")
-                    .desc()
-                    .first()
-                )
+                dl_stream = yt.streams.get_by_resolution(resolution=resolution) or yt.streams.get_lowest_resolution()
+                assert dl_stream is not None
 
                 logger.debug("download path: %s", download_path)
                 if prefix_number:

pytube/query.py

@@ -221,7 +221,7 @@ class StreamQuery:
         """
         return self
 
-    def get_by_itag(self, itag) -> Optional[Stream]:
+    def get_by_itag(self, itag:int) -> Optional[Stream]:
         """Get the corresponding :class:`Stream <Stream>` for a given itag.
 
         :param int itag:
@@ -234,6 +234,33 @@ class StreamQuery:
         """
         return self.itag_index.get(int(itag))
 
+    def get_by_resolution(self, resolution:str) -> Optional[Stream]:
+        """Get the corresponding :class:`Stream <Stream>` for a given resolution.
+        Stream must be a progressive mp4.
+
+        :param str resolution:
+            Video resolution i.e. "720p", "480p", "360p", "240p", "144p"
+        :rtype: :class:`Stream <Stream>` or None
+        :returns:
+            The :class:`Stream <Stream>` matching the given itag or None if
+            not found.
+
+        """
+        return self.filter(
+            progressive=True, subtype='mp4', resolution=resolution
+        ).first()
+
+    def get_lowest_resolution(self) -> Optional[Stream]:
+        """Get lowest resolution stream that is a progressive mp4.
+
+        :rtype: :class:`Stream <Stream>` or None
+        :returns:
+            The :class:`Stream <Stream>` matching the given itag or None if
+            not found.
+
+        """
+        return self.filter(progressive=True, subtype='mp4').order_by('resolution').desc().last()
+
     def first(self) -> Optional[Stream]:
         """Get the first :class:`Stream <Stream>` in the results.