Original commit message from CVS:
* docs/design/part-live-source.txt:
Add docs on how live sources should timestamp.
* libs/gst/base/gstbasesrc.c: (gst_base_src_do_sync):
Add some more debug info.
For subclasses that are live and like to sync, add aditional startup
latency to sync time and timestamps so that we timstamp according to the
design doc.