I get a segfault when i run reverse playback scenario with a particular mp4 file.

This is the stack trace.
gst_qtdemux_seek_to_previous_keyframe (qtdemux=<optimized out>) at qtdemux.c:3983
3983	  seg_media_start_mov = seg->trak_media_start;
(gdb) bt

+ Trace 235458

The crash is because, segment_index is -1.

For this particular sample, in gst_qtdemux_advance_sample

  /* see if we are past the segment */
  if (G_UNLIKELY (QTSAMPLE_DTS (stream, sample) >= segment->media_stop))
    goto next_segment;

This condition gets satisfied and in next_segment label, segment_index is set to -1.

I was able to solve the crash .. but not sure if it is really correct..

While checking if we are past the segment, >= is being checked, so even though qtsample time is same as media_stop, we are skipping to next_segment.
Changing the check to '>' fixes the issue. We are really past the segment only when is greater than media_stop. Not sure if >= is really needed..