We use to display the latency of each element in random order which is
not very convenient when comparing latency between different runs.
Sort them by "first activity" (the first latency reported for each
element) so it's consistent betwen runs.
This is the same logic when sorting and displaying element stats.
Latency is easier to read when formatted as time rather than displayed
as a flat number in ns.
Especially when displaying GST_CLOCK_TIME_NONE which is now formated as
99:99:99.999999999 instead of 18446744073709551615.
This will output latency information when parsing a log file with gst-stats that
has latency trace information. It will show the min, max and mean latency for
the pipeline and all its elements. It will also show the reported latency for
each element of the pipeline. Output example:
Latency Statistics:
pulsesrc0_src|fakesink0_sink: mean=190000043 min=190000043 max=190000043
Element Latency Statistics:
flacparse0_src: mean=45561281 min=654988 max=90467575
flacenc0_src: mean=89938883 min=81913512 max=97964254
flacdec0_src: mean=45804881 min=228962 max=91380801
Element Reported Latency:
pulsesrc0: min=10000000 max=200000000 ts=0:00:00.262846528
flacenc0: min=104489795 max=104489795 ts=0:00:00.262898616
flacparse0: min=0 max=0 ts=0:00:00.262927962
