This fixes the error:

mp4ff.c:91: error: static declaration of 'mp4ff_track_add' follows non-static declaration
mp4ffint.h:304: error: previous declaration of 'mp4ff_track_add' was here

diff -dur faad2/common/mp4ff/mp4ff.c src.faad2.1129998164.4669.1585831089/faad2/common/mp4ff/mp4ff.c
--- faad2/common/mp4ff/mp4ff.c	2004-01-11 16:52:18.000000000 +0100
+++ src.faad2.1129998164.4669.1585831089/faad2/common/mp4ff/mp4ff.c	2005-10-23 22:28:23.000000000 +0200
@@ -87,7 +87,7 @@
     if (ff) free(ff);
 }
 
-static void mp4ff_track_add(mp4ff_t *f)
+void mp4ff_track_add(mp4ff_t *f)
 {
     f->total_tracks++;