diff --git a/yt_dlp/YoutubeDL.py b/yt_dlp/YoutubeDL.py
index fb3f9337f8..f38697365a 100644
--- a/yt_dlp/YoutubeDL.py
+++ b/yt_dlp/YoutubeDL.py
@@ -669,7 +669,7 @@ class YoutubeDL:
                 'Set the LC_ALL environment variable to fix this.')
             self.params['restrictfilenames'] = True
 
-        self.outtmpl_dict = self.parse_outtmpl()
+        self._parse_outtmpl()
 
         # Creating format selector here allows us to catch syntax errors before the extraction
         self.format_selector = (
@@ -996,21 +996,19 @@ class YoutubeDL:
             self.report_warning(msg)
 
     def parse_outtmpl(self):
-        outtmpl_dict = self.params.get('outtmpl', {})
-        if not isinstance(outtmpl_dict, dict):
-            outtmpl_dict = {'default': outtmpl_dict}
-        # Remove spaces in the default template
-        if self.params.get('restrictfilenames'):
+        self.deprecation_warning('"YoutubeDL.parse_outtmpl" is deprecated and may be removed in a future version')
+        self._parse_outtmpl()
+        return self.params['outtmpl']
+
+    def _parse_outtmpl(self):
+        sanitize = lambda x: x
+        if self.params.get('restrictfilenames'):  # Remove spaces in the default template
             sanitize = lambda x: x.replace(' - ', ' ').replace(' ', '-')
-        else:
-            sanitize = lambda x: x
-        outtmpl_dict.update({
-            k: sanitize(v) for k, v in DEFAULT_OUTTMPL.items()
-            if outtmpl_dict.get(k) is None})
-        for _, val in outtmpl_dict.items():
-            if isinstance(val, bytes):
-                self.report_warning('Parameter outtmpl is bytes, but should be a unicode string')
-        return outtmpl_dict
+
+        outtmpl = self.params.setdefault('outtmpl', {})
+        if not isinstance(outtmpl, dict):
+            self.params['outtmpl'] = outtmpl = {'default': outtmpl}
+        outtmpl.update({k: sanitize(v) for k, v in DEFAULT_OUTTMPL.items() if outtmpl.get(k) is None})
 
     def get_output_path(self, dir_type='', filename=None):
         paths = self.params.get('paths', {})
@@ -1248,7 +1246,7 @@ class YoutubeDL:
     def _prepare_filename(self, info_dict, *, outtmpl=None, tmpl_type=None):
         assert None in (outtmpl, tmpl_type), 'outtmpl and tmpl_type are mutually exclusive'
         if outtmpl is None:
-            outtmpl = self.outtmpl_dict.get(tmpl_type or 'default', self.outtmpl_dict['default'])
+            outtmpl = self.params['outtmpl'].get(tmpl_type or 'default', self.params['outtmpl']['default'])
         try:
             outtmpl = self._outtmpl_expandpath(outtmpl)
             filename = self.evaluate_outtmpl(outtmpl, info_dict, True)
@@ -1878,7 +1876,7 @@ class YoutubeDL:
             and (
                 not can_merge()
                 or info_dict.get('is_live') and not self.params.get('live_from_start')
-                or self.outtmpl_dict['default'] == '-'))
+                or self.params['outtmpl']['default'] == '-'))
         compat = (
             prefer_best
             or self.params.get('allow_multiple_audio_streams', False)
@@ -3224,7 +3222,7 @@ class YoutubeDL:
     def download(self, url_list):
         """Download a given list of URLs."""
         url_list = variadic(url_list)  # Passing a single URL is a common mistake
-        outtmpl = self.outtmpl_dict['default']
+        outtmpl = self.params['outtmpl']['default']
         if (len(url_list) > 1
                 and outtmpl != '-'
                 and '%' not in outtmpl