Allow specifying path in `--external-downloader`

README.md

@@ -326,9 +326,10 @@ Then simply run `make`. You can also run `make yt-dlp` instead to compile only t
     --no-hls-use-mpegts              Do not use the mpegts container for HLS
                                      videos. This is default when not
                                      downloading live streams
-    --external-downloader NAME       Use the specified external downloader.
+    --external-downloader NAME       Name or path of the external downloader to
-                                     Currently supports aria2c, avconv, axel,
+                                     use. Currently supports aria2c, avconv,
-                                     curl, ffmpeg, httpie, wget
+                                     axel, curl, ffmpeg, httpie, wget
+                                     (Recommended: aria2c)
     --downloader-args NAME:ARGS      Give these arguments to the external
                                      downloader. Specify the downloader name and
                                      the arguments separated by a colon ":". You

yt_dlp/downloader/__init__.py

@@ -53,7 +53,7 @@ def get_suitable_downloader(info_dict, params={}, default=HttpFD):
     external_downloader = params.get('external_downloader')
     if external_downloader is not None:
         ed = get_external_downloader(external_downloader)
-        if ed.can_download(info_dict):
+        if ed.can_download(info_dict, external_downloader):
             return ed
 
     if protocol.startswith('m3u8'):

yt_dlp/downloader/external.py

@@ -85,16 +85,16 @@ class ExternalFD(FileDownloader):
         return self.params.get('external_downloader')
 
     @classmethod
-    def available(cls):
+    def available(cls, path=None):
-        return check_executable(cls.get_basename(), [cls.AVAILABLE_OPT])
+        return check_executable(path or cls.get_basename(), [cls.AVAILABLE_OPT])
 
     @classmethod
     def supports(cls, info_dict):
         return info_dict['protocol'] in cls.SUPPORTED_PROTOCOLS
 
     @classmethod
-    def can_download(cls, info_dict):
+    def can_download(cls, info_dict, path=None):
-        return cls.available() and cls.supports(info_dict)
+        return cls.available(path) and cls.supports(info_dict)
 
     def _option(self, command_option, param):
         return cli_option(self.params, command_option, param)

yt_dlp/options.py

@@ -650,8 +650,8 @@ def parseOpts(overrideArguments=None):
         '--external-downloader',
         dest='external_downloader', metavar='NAME',
         help=(
-            'Use the specified external downloader. '
+            'Name or path of the external downloader to use. '
-            'Currently supports %s' % ', '.join(list_external_downloaders())))
+            'Currently supports %s (Recommended: aria2c)' % ', '.join(list_external_downloaders())))
     downloader.add_option(
         '--downloader-args', '--external-downloader-args',
         metavar='NAME:ARGS', dest='external_downloader_args', default={}, type='str',