Hello!
[ I hope I am on-topic here. I have considered to post this to the
tuxbox-forum, but decided to post it here because it has more to
do with stream encodings than with the dbox2.]
I'm trying to transport live streams over a 10BaseT[1] network. With
most channels, there is no problem. But on some programs (most notably
the german ARD) the bitrate is changing pretty much. After a lot of
investigations, i've got some assumptions:
- Most of the bandwidth is consumed by the video-pid (pid 101). This is
not really a surprise. I mention this here only because I need a reason
to ignore the other PIDs :)
- Most of the time the bitrate on the video-pid is quite low (about
2000..3500 TS packets per second, which gives something below 7MBps).
But sometimes (every 10..20 minutes) the bitrate raises dramatically[2]
for a couple of seconds (sometimes just one second, sometimes up to 20
seconds) and comes down again to the 2000..3500 range. I really don't
understand what is going on here. How come this dramatic raise without
increase in the motion or in picture-details? Is this raise really
caused by the video stream?
- Next, I checked how much stuffing (via adaptation field) is inserted.
It seems to me that about 6..8% stuffing is inserted.
My guess is that with recoding the TS into PS, it should be possible to
avoid this stuffing. In addition, the TS header (another 2%) can be
avoided. With a little luck, this might be sufficient to get the bitrate
below 10MBps (check footnote [2]).
Can anyone confirm or correct my assumptions or have any other idea what
might be going wrong here?
I would like to try this recoding (TS->PS). Extracting PES from the TS
is not really a probem. But unfortunately, I could not find any
description how PS streams are to be constructed. Any pointers?
Thanks in advance!
[1] Using 100BaseT is no option, since this is for the dbox2, which
is limited to 10BaseT by hardware.
[2] I have seen bitrates of up to 5400 TS-packets per second. This gives
about 1015200 cps, which is obviously too much for a 10BaseT network
=8).
--
No software patents in Europe -- http://nosoftwarepatents.com
-- Josef Wolf -- jw@xxxxxxxxxxxxx --
