[streaming] Multicast errors: discontinuity at reception

[Javier Gálvez Guerrero]

Hi,

I am trying to stream multicast videos through a hybrid wireless-wired
network and I am having some problems at wireless clients. I have checked
with differents devices and even with different networks (laboratory and
home), but the results are the same: "ts warning: discontinuity received 0xX
instead of 0xX (pid = 68 or 69)" messages, so having some video and audio
interruptions and poor frame decoding results.

I stream from a VLC server (through VLM, VLC 0.8.6d), Ubuntu Linux 32 bits
based, running in a laptop. It serves RTSP VOD videos and UDP multicast,
both configured with VLM telnet interface. It streams via 802.11g at 54 Mbps
to a Cisco Aironet 1200 series access point, connected to a switch with many
other computers. Then I have two clients: a desktop and a laptop. The
desktop is wired and it receives both VOD and the multicast streams
perfectly, but the laptop, connected to the network with 802.11g receives
VOD with no problems but the multicast stream with many discontinuity
errors. If I connect the laptop to the wired network the multicast streams
are received with no problems.

I configure the scheduled multicast streaming:

> new test broadcast enabled
> setup test input /media/sda2/diptv/server/contents/test.mpg
> setup test output #standard{mux=ts,access=udp,dst=239.255.1.5:60101}
> new test_tv schedule enabled
> setup test_tv date 2008/02/28-14:50:00
> setup test_tv append control test play

I have tried with different videos, different wireless receivers, different
802.11g channels and transmission rates (and many other access point
features), streaming from a wired and wireless server, with a WIFI
Conceptronic router or a D-Link DWL700 access point instead the Cisco
Aironet 1200 and receiving in a Linux or WinXP client with the same results,
the raw of discontinuity errors at receiver. I have also tried increasing
the buffer size of VLC for UDP muxer with no effect.

I have launched Wireshark protocol analyzer to track the udp packets on the
wired desktop and on the wireless laptop and the difference are some random
missing packets on the wireless laptop network interface, obvious losses.

So what I would like to know is if somebody has faced this problem with
multicast streaming in a wireless environment and, if it has been finally
solved, how to do it. If the solution is a different access point I would
like to know which ones have worked properly with this issue.


Thanks a lot.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.videolan.org/pipermail/streaming/attachments/20080303/21823765/attachment.htm