vlc hardware encoding for real-time screen multicast

[samb]

We are preparing a solution to multicast the teacher's screen to 40 students' pcs. Teacher and students pcs can be both Ubuntu and Windows.
Some solutions were tested :
* iTalc ... not stable yet.
* multicast a "vnc -viewonly" ... no solution found
* capture the screen with VLC and multicast it.

That latest seems to work ... except that with a resolution like 1920x1200 it is just too much CPU intensive.
One idea would be to capture only the 4th of the screen. CPU is not saturated anymore but everything becomes really slow and the surface is too small anyway.
A second idea is to buy some hardware (e.g. a PCI card) which will be dedicated to real-time video encoding.
I could find this : http://wiki.videolan.org/Hardware_Compatibility_list but without knowing which one is still available and fits the requirements.

Anyone has an experience/knowledge on it?
Thanks!

[thomasferre]

Hi

I work in the Lille faculty of medecine in France.

We are using VLC to multicast HD (1920*1080) streaming lectures (PC or HD camera).

We are using the extremergb hardware :

http://www.xtremergb.com/categories/HDM ... ure-Cards/

The hardware is working very well (about 1 000 euros) but only under windows.

To do live H264 full HD capture at 30 fps, you will need a big cpu (quadcore).

Regards

[Jean-Baptiste Kempf]

Nice. Can you share your experiment a bit more?

[thomasferre]

Hi

We have 3 000 students in the first year of medical school in Lille (PACES).

We only take the 450 best students to pursuit medical studies.

As we don't have a signle 3 000 seats amphitheatre for the lectures, we do multicast streaming in several amphitheatres (600 seats, 300 seats, ...).

The Extremrgb is a very good full hd capture card.

To use H264 encoder at 30 fps, we need a quad core CPU.

I helped the Clermond Ferrand medical school to use the same infrastructure.

Regards

[Jean-Baptiste Kempf]

OS version? VLC version? Any special tweaks?

[thomasferre]

OS windows XP (extremergb driver only on windows)

We were using VLC 0.86i because it was the most stable and efficient H264 encoder.

We tried 1.1.x versions but there was a cyclic visual remance on black boards with H264 encoder.

The 1.1.9 H264 seemed OK but it seems that RTP causes VLC to crash after a few hours.

I am trying 1.1.10, which has a RTP bug fix.

Hope it will solve the pb

[Jean-Baptiste Kempf]

1.1.x should have a x264 version way newer, and thus, way faster...

[thomasferre]

I tried windows 1.1.10.

H264 RTP streaming crashes VLC after about 8 hours of streaming.

So I got back to 0.86i, which is quite stable.

[Jean-Baptiste Kempf]

Out of memory situations? What are the logs?

[thomasferre]

Hi

I am busy right now but I asked a colleague to post the VLC log of the crash.

Regards