[postprocessor/ffmpeg] Fix avconv processing broken in #19025 (closes #19067)

youtube_dl/postprocessor/ffmpeg.py

@@ -217,11 +217,13 @@ class FFmpegPostProcessor(PostProcessor):
                 encodeArgument('-i'),
                 encodeFilename(self._ffmpeg_filename_argument(path), True)
             ])
-        cmd = ([encodeFilename(self.executable, True), encodeArgument('-y')] +
+        cmd = [encodeFilename(self.executable, True), encodeArgument('-y')]
-               [encodeArgument('-loglevel'), encodeArgument('repeat+info')] +
+        # avconv does not have repeat option
-               files_cmd +
+        if self.basename == 'ffmpeg':
-               [encodeArgument(o) for o in opts] +
+            cmd += [encodeArgument('-loglevel'), encodeArgument('repeat+info')]
-               [encodeFilename(self._ffmpeg_filename_argument(out_path), True)])
+        cmd += (files_cmd +
+                [encodeArgument(o) for o in opts] +
+                [encodeFilename(self._ffmpeg_filename_argument(out_path), True)])
 
         if self._downloader.params.get('verbose', False):
             self._downloader.to_screen('[debug] ffmpeg command line: %s' % shell_quote(cmd))