Created attachment 179290 [details] [review]
unit test which triggers the leak

The muxer will leak the ebml_write->caps after reset. I've seen the problem in plugins-good 0.10.24 but i am pretty sure it also exists in the latest version of the muxer.

The easiest way to reproduce the leak is:

gst_element_state (pipe, GST_STATE_PLAY);
gst_element_state (pipe, GST_STATE_NULL);
gst_element_state (pipe, GST_STATE_PLAY);

and gst_matroska_mux_start () will create new caps without unreffing the old caps. The suggested fix is to unref the caps in gst_ebml_write_reset ():

void
gst_ebml_write_reset (GstEbmlWrite * ebml)
{
  ebml->pos = 0;

  if (ebml->cache) {
    gst_byte_writer_free (ebml->cache);
    ebml->cache = NULL;
  }

  if (ebml->caps) {
    gst_caps_unref (ebml->caps);
    ebml->caps = NULL;
  }

  ebml->last_write_result = GST_FLOW_OK;
  ebml->timestamp = GST_CLOCK_TIME_NONE;
  ebml->need_newsegment = TRUE;
}

Attached is also a unit test which triggers the problem.