[downloader/external] Add support for custom options (Fixes #4885, closes #5098)

2 files changed, 14 insertions, 3 deletions

diff --git a/youtube_dl/downloader/common.py b/youtube_dl/downloader/common.py
index 3ae90021a..8ed5c19a6 100644
--- a/youtube_dl/downloader/common.py
+++ b/youtube_dl/downloader/common.py
@@ -42,6 +42,8 @@ class FileDownloader(object):
     max_filesize:       Skip files larger than this size
     xattr_set_filesize: Set ytdl.filesize user xattribute with expected size.
                         (experimenatal)
+    external_downloader_args:  A list of additional command-line arguments for the
+                        external downloader.
 
     Subclasses of this one must re-define the real_download method.
     """
diff --git a/youtube_dl/downloader/external.py b/youtube_dl/downloader/external.py
index 51c41c704..1673b2382 100644
--- a/youtube_dl/downloader/external.py
+++ b/youtube_dl/downloader/external.py
@@ -51,6 +51,13 @@ class ExternalFD(FileDownloader):
             return []
         return [command_option, source_address]
 
+    def _configuration_args(self, default=[]):
+        ex_args = self.params.get('external_downloader_args')
+        if ex_args is None:
+            return default
+        assert isinstance(ex_args, list)
+        return ex_args
+
     def _call_downloader(self, tmpfilename, info_dict):
         """ Either overwrite this or implement _make_cmd """
         cmd = self._make_cmd(tmpfilename, info_dict)
@@ -79,6 +86,7 @@ class CurlFD(ExternalFD):
         for key, val in info_dict['http_headers'].items():
             cmd += ['--header', '%s: %s' % (key, val)]
         cmd += self._source_address('--interface')
+        cmd += self._configuration_args()
         cmd += ['--', info_dict['url']]
         return cmd
 
@@ -89,15 +97,16 @@ class WgetFD(ExternalFD):
         for key, val in info_dict['http_headers'].items():
             cmd += ['--header', '%s: %s' % (key, val)]
         cmd += self._source_address('--bind-address')
+        cmd += self._configuration_args()
         cmd += ['--', info_dict['url']]
         return cmd
 
 
 class Aria2cFD(ExternalFD):
     def _make_cmd(self, tmpfilename, info_dict):
-        cmd = [
-            self.exe, '-c',
-            '--min-split-size', '1M', '--max-connection-per-server', '4']
+        cmd = [self.exe, '-c']
+        cmd += self._configuration_args([
+            '--min-split-size', '1M', '--max-connection-per-server', '4'])
         dn = os.path.dirname(tmpfilename)
         if dn:
             cmd += ['--dir', dn]