andoni@andoni-desktop:~/gst/head/gst-plugins-good (master)$ git show
commit ed01d3c07647254b2f722a743b162e6bcd93fca7
Author: Andoni Morales Alastruey <amorales@flumotion.com>
Date:   Mon Jul 26 13:38:31 2010 +0200

    qtdemux: set the pixel-aspect-ratio field also for par=1/1

diff --git a/gst/qtdemux/qtdemux.c b/gst/qtdemux/qtdemux.c
index 63d9aca..4ab565c 100644
--- a/gst/qtdemux/qtdemux.c
+++ b/gst/qtdemux/qtdemux.c
@@ -3981,11 +3981,11 @@ gst_qtdemux_add_stream (GstQTDemux * qtdemux,
         /* calculate the pixel aspect ratio using the display and pixel w/h */
         n = stream->display_width * stream->height;
         d = stream->display_height * stream->width;
-        if (n != d) {
-          GST_DEBUG_OBJECT (qtdemux, "setting PAR to %d/%d", n, d);
-          gst_caps_set_simple (stream->caps, "pixel-aspect-ratio",
-              GST_TYPE_FRACTION, n, d, NULL);
-        }
+        if (n == d)
+          n = d = 1;
+        GST_DEBUG_OBJECT (qtdemux, "setting PAR to %d/%d", n, d);
+        gst_caps_set_simple (stream->caps, "pixel-aspect-ratio",
+            GST_TYPE_FRACTION, n, d, NULL);
       }

       /* qt file might have pasp atom */