Hey Rüdiger,
so we have to do an additional decoding and re-encoding to h.264
for the streaming.
Doesn't your Hauppauge model provide a "raw" video output? Have you
considered using it instead the mpeg2-encoded one? We have tested two
or three different models and all of them "created" three devices in
the OS: one corresponding to the raw audio, other to the raw video,
and other to the mpeg2-encoded combination of the former. I know that
decoding mpeg2 is not very cpu-consuming, but you can give it a try
anyway.
Best regards
2012/2/9 Ruediger Rolf <[email protected]
<mailto:[email protected]>>
Hi Kevin,
we only use two i7 for capturing. One of these is a Windows PC
using the Blackmagic H.264 Pro Recorder box (that's why windows)
for HD-recording. But as this box is still missing the APIs that
Blackmagic promissed the recording is still manual. The machine is
quite over-powered (20-30% CPU load while capturing 1280x800 vga
and 1080i video simultanous).
The second i7 is in use for our live streaming test system, that
we use for over a semester now. If we record, enable confidence
monitoring and do h.264-live-streaming for 2 streams (SD-video
only) with the Matterhorn Capture Agent we are getting to 40-50%
CPU load. So again this machine could be slower. I production we
used only single stream live-streaming, which ran at about 30% CPU
load. We are using the Hauppauge PVR-150 in all our machines, so
we have to do an additional decoding and re-encoding to h.264 for
the streaming.
Both machines are Dell Optiplex MT 980 with the cheapest quad-core
i7 and 4 GB RAM.
In general we use Dell Optiplex 780 as recorders with a Pentium 4
Dual Core with 2.8 Ghz and 4GB RAM. They run at 70-80% CPU load
while recording 2 streams. With the optimisations in Matterhorn
1.3 these machines can do recording and live streaming at 90-100%
CPU load, what may cause some frame drops if we are unfortunate.
For only recordings the general CPU load will go down
significantly too with 1.3. Again we are using Hauppauge PVR-150
and epiphan VGA2USB LR on all of these machines.
Currently if I would need to buy new computers as recorders I
would recommend a Dell Optiplex MT 790 with a i5-2400. As this
would probably have enough power for reliable live-streaming at least.
If you are interested I can try to check how much CPU load it will
take on the i7 to capture from the epiphan device and a Blackmagic
Intensity Pro HD-capture-card. This is already on my to do list,
but I had no time to evaluate this yet. The capture card is lying
on my desk for a a while already...
Rüdiger
Am 08.02.2012 18:14, schrieb Kevin Chan:
Hi Nils,
Thanks for your info. While I have heard of other universities
running different hardware, this is the first documented case
(as far as I know) of someone specifically stating that
someone is running capture agents using i5/i7 cores.
At UC Berkeley, we are likely to need some higher powered
capture agents to do some HD camera captures (and possibly for
SD camera captures) and that's why I have been trying to get
the Opencast Community to share their hardware/software/config
setup on this list (and even better would be on the Opencast
Wiki).
As such, can you share some basic information about your setup
(perhaps with a note on the path that led you to your
particular setup)?
Even though we are still in our very early stages of
testing/silent piloting, if I have a few minutes today, I will
try to get a "capture agent setup page" for UC Berkeley
started on the Opencast wiki so that others can benefit from
this information.
Kevin Chan
Operations Team
Educational Technology Services
UC Berkeley
On 2/7/12 10:46 PM, Nils Birnbaum wrote:
Hi Kevin,
besides Gallicaster, this is a general problem. Most
Universities run i5
or i7 processor to capture sufficient framerates for
2-stream-recording.
So you have a trade off between CPU-Power and framerate
(and some RAM) to
get a result that match with the needs of your institution.
Regards
Nils
Hi Ruben,
Thanks for the info, your approach sounds reasonable
to me.
I am still unclear on what hardware setup you are
using. I found this
page -
http://wiki.teltek.es/display/Galicaster/Hardware+recommendations
- so I am guessing you are probably running your
captures against an
Intel i3 processor with some sort of Hauppauge card.
So in summary:
a) using the above hardware setup, you had some video
sync/dropped frame
rate issues
b) these issues were fixed with "a different pipeline
structure with the
element 'videorate' to guarantee the video stream
synchronization"
In theory, adding "videorate" to the MH capture agent
pipeline should
also fix this issue, but the placement of this element
is probably key
to the whole thing!
Let me know if I got any of the above wrong.
Kevin Chan
Operations Team
Educational Technology Services
UC Berkeley
On 2/6/12 4:51 AM, Rubén Pérez wrote:
Hi all,
The pipeline we are using in Galicaster is rather
different than the
one used in the standard capture agent in many
ways, the first one
coming to my mind being the fact that Galicaster
needs to provide
video feedback and the CA doesn't.
Still, I will take a look and see if we can commit
some changes to
improve the synchronization quality. I cannot
guarantee though.
The pipeline used is in the code of Galicaster,
available at
www.galicaster.org
<http://www.galicaster.org><http://www.galicaster.org>
.
Sorry I cannot be more specific right now. When I
have some spare time
I'll try to document myself on this topic and try
to apply a patch
based on our research in Galicaster, if that's
feasible without
altering the current CA pipeline too much. Does
this sound reasonable?
Regards
2012/2/2 Kevin Chan<[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>>
Hi Ruben,
Was this "fix" done against the referenced MH
capture hardware or
some other hardware setup?
In any case, thanks for the info, it would be
great if you can
provide this info for the MH developers in:
http://opencast.jira.com/browse/MH-8505
Also, if you can provide the full pipeline
structure, that would
be great (for novice pipeline constructors
like me).
Kevin Chan
Operations Team
Educational Technology Services
UC Berkeley
On 1/30/12 5:38 AM, Tobias Wunden wrote:
Hi Ruben,
any chance that fix will make it back into
trunk anytime soon? It
would have been great to have this in for
1.3 as well, given that
you seem to have sorted out that issue a
while ago.
Tobias
On 30.01.2012, at 09:15, Rubén
Pérez<[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>> wrote:
Hi Kevin,
I can also confirm that we experienced
the same frame drop/out
of sync problem in long recordings,
both in the capture agent
and also in Galicaster's development
stages. Finally, we
discovered that the key was a
different pipeline structure with
the element 'videorate' to guarantee
the video stream
synchronization.
Maybe you could try and add this
element to the CA's standard
pipeline, and see what happens. Of
course, you can also try
Galicaster :)
Good luck
Rubén
On 25 Xan, 2012 07:18, "Kevin
Chan"<[email protected]
<mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>> wrote:
Hi all,
During preliminary testing of a 2h
15m capture (which we
intend to post produce for
YouTube), UC Berkeley discovered
that the capture files for video
and screen were off by 15m
(with the screen capture via
Epiphan being 15m short), which
is more or less unacceptable to
our post production folks
(as it is very difficult for them
to stitch this back
together). This is likely to be
due to dropped frame rate,
but it is a bit difficult to confirm.
I am wondering if anyone else
(besides Saskatchewan folks,
who confirmed this issue) has
encounter this issue and how
they are working around it. I
imagine that lowering
framerates and bitrates would
work, though some initial
testing using various capture
agent configurations seems to
suggest that the capture files are
still off by a few
minutes even with the CPUs being
not fully taxed.
We are using the reference capture
agent hardware and very
basic capture agent settings. This
issue has been filed in
MH Jira if anyone is interested:
http://opencast.jira.com/browse/MH-8505
Finally, we have heard that there
are various hardware and
configuration setups for
Matterhorn Capture Agents in
production. I think it would be
great if that we, as a
community, can share this
information (via the MH wiki) to
help each other understand and
learn about the various use
cases and setups that are employed.
Thanks,
--
Kevin Chan
Operations Team
Educational Technology Services
UC Berkeley
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--
________________________________________________
Rüdiger Rolf, M.A.
Universität Osnabrück - Zentrum virtUOS
Heger-Tor-Wall 12, 49069 Osnabrück
Telefon: (0541) 969-6511 - Fax: (0541) 969-16511
E-Mail: [email protected] <mailto:[email protected]>
Internet: www.virtuos.uni-osnabrueck.de
<http://www.virtuos.uni-osnabrueck.de>
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