rtpjitterbuffer: Does not handle bursts properly

Submitted by Nirbheek Chauhan @nirbheek

Link to original bug (#746035)

Description

Created attachment 299099
Sample rtsp audio stream which yields duplicate timestamps with rtpjitterbuffer

When the attached gdp-payloaded file is run through rtpjitterbuffer, with mode=slave (the default), the output audio has buffers with duplicate pts, but not with mode=buffer/synced/none. Those buffers all seem to contain silence (see bug 746032).

Bad:
gst-launch-1.0 filesrc location=output-gdp-audio.bin ! gdpdepay ! rtpjitterbuffer ! rtpmp4adepay ! decodebin ! ...

Good:
gst-launch-1.0 filesrc location=output-gdp-audio.bin ! gdpdepay ! rtpjitterbuffer mode=buffer ! rtpmp4adepay ! decodebin ! ...

gst-launch-1.0 filesrc location=output-gdp-audio.bin ! gdpdepay ! rtpjitterbuffer mode=synced ! rtpmp4adepay ! decodebin ! ...

gst-launch-1.0 filesrc location=output-gdp-audio.bin ! gdpdepay ! rtpjitterbuffer mode=none ! rtpmp4adepay ! decodebin ! ...

All the incoming packets are sequential and evenly-spaced (captured from gst-rtsp-server over a link-local network), so in theory there shouldn't be a "discontinuity" like that.

Attachment 299099, "Sample rtsp audio stream which yields duplicate timestamps with rtpjitterbuffer":
output-gdp-video.bin