Index: libhb/muxmp4.c
===================================================================
--- libhb/muxmp4.c	(revision 1278)
+++ libhb/muxmp4.c	(working copy)
@@ -444,11 +444,20 @@
         }
     
         /* Video */
+        
+        if ( job->vfr ) 
+        { 
+            int64_t bias = ( buf->start * job->arate / 90000 ) - m->sum_dur;
+            duration = ( buf->stop - buf->start ) * job->arate / 90000 + bias;
+        } 
+        else 
+        { 
+            duration    = ( buf->stop * job->arate / 90000 ) - m->sum_dur; 
+        }
+        
         /* Because we use the audio samplerate as the timescale,
            we have to use potentially variable durations so the video
            doesn't go out of sync */
-        int64_t bias = ( buf->start * job->arate / 90000 ) - m->sum_dur;
-        duration = ( buf->stop - buf->start ) * job->arate / 90000 + bias;
         m->sum_dur += duration;
     }
     else