Index: MPlayer-r33333/libmpdemux/video.c
===================================================================
--- MPlayer-r33333.orig/libmpdemux/video.c	2011-04-30 13:42:17.000000000 +0200
+++ MPlayer-r33333/libmpdemux/video.c	2011-04-30 13:43:31.000000000 +0200
@@ -61,6 +61,8 @@
   VIDEO_OTHER
 } video_codec_t;
 
+#define FOURCC_THEORA mmioFOURCC('t', 'h', 'e', 'o')
+
 static video_codec_t find_video_codec(sh_video_t *sh_video)
 {
   demux_stream_t *d_video=sh_video->ds;
@@ -581,7 +583,8 @@
     frame_time*=sh_video->frametime;
 
     // override frame_time for variable/unknown FPS formats:
-    if(!force_fps) switch(demuxer->file_format){
+    if(!force_fps && sh_video->format != FOURCC_THEORA)
+      switch(demuxer->file_format){
       case DEMUXER_TYPE_GIF:
       case DEMUXER_TYPE_MATROSKA:
       case DEMUXER_TYPE_MNG: