tsparse: doesn't output aligned ts packets (streaming from file to vlc doesn't recover on unaligned ts)

Submitted by Andreas Frisch @fraxinas

Link to original bug (#747457)

Description

i've observed that i couldn't stream certain ts files from gst-rtsp-server to vlc (gstreamer as a client works) so i digged a bit and found out that the trigger for the issue were random bytes before the first ts packet

this is easily reproducable:
just prepend a few bytes before a valid, working ts file
printf "blafaselfoobar1234567890abcdefghijk" | cat - streamtest.ts > streamtest-broken.ts

start gst-rtsp-server
test-launch "( filesrc location=streamtest-broken.ts ! tsparse set-timestamps=true ! queue ! rtpmp2tpay name=pay0 pt=96 )"

playback with vlc