use yt-dlp by default (#1850, #2028)

gallery_dl/downloader/ytdl.py

@@ -39,7 +39,7 @@ class YoutubeDLDownloader(DownloaderBase):
         if not ytdl_instance:
             ytdl_instance = self.ytdl_instance
             if not ytdl_instance:
-                module = __import__(self.config("module") or "youtube_dl")
+                module = ytdl.import_module(self.config("module"))
                 self.ytdl_instance = ytdl_instance = ytdl.construct_YoutubeDL(
                     module, self, self.ytdl_opts)
                 if self.outtmpl == "default":

gallery_dl/extractor/ytdl.py

@@ -23,9 +23,9 @@ class YoutubeDLExtractor(Extractor):
 
     def __init__(self, match):
         # import main youtube_dl module
-        module_name = self.ytdl_module_name = config.get(
-            ("extractor", "ytdl"), "module") or "youtube_dl"
-        module = __import__(module_name)
+        ytdl_module = ytdl.import_module(config.get(
+            ("extractor", "ytdl"), "module"))
+        self.ytdl_module_name = ytdl_module.__name__
 
         # find suitable youtube_dl extractor
         self.ytdl_url = url = match.group(1)
@@ -34,7 +34,7 @@ class YoutubeDLExtractor(Extractor):
             self.ytdl_ie_key = "Generic"
             self.force_generic_extractor = True
         else:
-            for ie in module.extractor.gen_extractor_classes():
+            for ie in ytdl_module.extractor.gen_extractor_classes():
                 if ie.suitable(url):
                     self.ytdl_ie_key = ie.ie_key()
                     break
@@ -48,7 +48,7 @@ class YoutubeDLExtractor(Extractor):
 
     def items(self):
         # import subcategory module
-        ytdl_module = __import__(
+        ytdl_module = ytdl.import_module(
             config.get(("extractor", "ytdl", self.subcategory), "module") or
             self.ytdl_module_name)
         self.log.debug("Using %s", ytdl_module)

gallery_dl/ytdl.py

@@ -14,6 +14,15 @@ import itertools
 from . import text, util, exception
 
 
+def import_module(module_name):
+    if module_name is None:
+        try:
+            return __import__("yt_dlp")
+        except ImportError:
+            return __import__("youtube_dl")
+    return __import__(module_name.replace("-", "_"))
+
+
 def construct_YoutubeDL(module, obj, user_opts, system_opts=None):
     opts = argv = None
     config = obj.config