streaming over network to multiple clients in sync

[Marc Murphy]

Hi,
Just on a note, why are you using rtsp to send to multiple clients, you will always have loading issues if using lots of clients.

You would normally use a multicast system to allow for low load  (on the server and network) and clients can then easily subscribe/unsubscribe to the service.  The server would normally be constantly running.

Just maybe something else to look at.

Cheers
Marc
________________________________________
From: gstreamer-devel-bounces+marcmltd=marcm.co.uk at lists.freedesktop.org [gstreamer-devel-bounces+marcmltd=marcm.co.uk at lists.freedesktop.org] on behalf of John Ruemker [john.ruemker at gmail.com]
Sent: 15 February 2012 15:40
To: gstreamer-devel at lists.freedesktop.org
Subject: streaming over network to multiple clients in sync

Hey all,
I am a relative gstreamer n00b, but I've read the application
development manual and gone through as many pipeline examples as I can
find to try and get up to speed.

I'm trying to figure out the ideal pipeline for streaming over the
network to multiple clients.  The test I'm working with now is 720p mkvs
using filesrc on the server streaming to multiple clients that will need
to play back in-sync (more on that below).  I've come up with a number
of different pipelines that will stream it and play on the clients, but
the main two problems I need help solving are:

a) Performance.  I can't seem to get smooth playback on the client in
any of the pipelines I've tried.  Most of them have been pieced together
from examples I've found (I still don't have much familiarity with the
different plugins), so its quite possible I'm doing something stupid or
missing an important setting.  I'm able to play the same file over NFS
using different gstreamer players, so I'm convinced its something in the
pipeline.  Here's an example of what I've tried:

### server
# gst-launch -v gstrtpbin name=rtpbin filesrc location=file.mkv !
decodebin ! x264enc ! rtph264pay ! queue max-size-buffers=2
max-size-time=0 max-size-bytes=0  ! rtpbin.send_rtp_sink_0
rtpbin.send_rtp_src_0 ! udpsink host=192.168.2.2 port=5000
rtpbin.send_rtcp_src_0 ! udpsink preroll-queue-len=10000 port=5001
sync=false async=false udpsrc port=5005 ! rtpbin.recv_rtcp_sink_0

### client
# gst-launch udpsrc port=5000 caps="application/x-rtp,
media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264"
! .recv_rtp_sink_0     gstrtpbin ! decodebin ! xvimagesink

I've also tried without RTP, tcp instead of udp, and tweaking some of
the buffer/preroll settings to no avail.  Anyone have a good example of
a pipeline that performs well over the network?

b) Playing in sync on multiple clients. I need playback to be
synchronized on the clients, but can't figure out how to do so.  I
understand that I can use gst_net_time_provider_new() and
gst_net_client_clock_new(), but as I understand that will only cause the
client to use the same clock for playback, but their position in the
streams will not be synchronized.  Any idea how I can accomplish this?
Ideally the pipeline would be set up such that if I pause or set the
position on the client it would carry back to the server and propagate
to the other clients, but if the only way is to communicate from
client->server at an application level to have the server do it, that's
fine.

Thanks in advance for any help you can provide!

-John
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