Override the value for file size in bytes. Useful for getting sensible track length values in feed mode or for HTTP streams.

https://www.mpg123.de/api/group__mpg123__status.shtml#gad0301e80dbc3f48e47e27d39cd328755

src/decoder/plugins/Mpg123DecoderPlugin.cxx

@@ -353,6 +353,10 @@ mpd_mpg123_stream_decode(DecoderClient &client, InputStream &is)
 	};
 
 	mpd_mpg123_open_stream(*handle, iohandle);
+
+	if (is.KnownSize())
+	    mpg123_set_filesize(handle, is.GetSize());
+
 	Decode(client, *handle, is.IsSeekable());
 }