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Our school radio station is currently supplementing the audio based lessons with a slideshare meeting-based slideshow. Unfortunately slideshare has been pretty buggy and any time we want to stream video (say off youtube) the video fails because of the traffic generated by 20 devices loading the same video stream at the same time.

We could mitigate this if we could stream a screencast live on the local network - we could literally stream a keynote presentation off the radio mac's screen and any video content straight from the browser. We don't need to worry about bandwidth internally - it's our external internet connection that causes our lag problems.

I've tried QT Streaming Server but it's not so well supported and I can't stream a screencast, only a webcam video stream.

Is there an easy way to stream a live mac screencast locally to more than one mac client?

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Please: what's the age range of the students? –  Graham Perrin Mar 26 '13 at 3:32
    
OS X is pretty weak at this part. –  Shane Hsu Mar 26 '13 at 8:18
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@GrahamPerrin students are aged 5 - 12; we're a primary school. –  glenstorey Mar 26 '13 at 16:20
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3 Answers 3

To live stream your desktop, you will want to get two pieces of software:

Software to capture your desktop as a stream and redirect:

1) CamTwist - http://camtwiststudio.com/download/ - does desktop live capture and turns it into a video stream that is compatible for "webcam" input applications. I've used this to live stream my desktop to ustream.tv, Google Hangout, etc. (free)

AND

2) SoundFlower - https://code.google.com/p/soundflower/ - Allows you to redirect the system sound output so that it can be routed as an input for your stream (free)

Software to publish from your desktop:

1) EvoCam - http://www.evological.com/evocam.html - does a local http streaming server to serve your "webcam" stream out to the local area network. ( $30 )

OR

2) VLC - http://www.videolan.org/vlc/streaming.html - VideoLAN streaming component of VLC to livestream your "webcam" produced from your camtwist/soundflower combo. (free)

Can post more details, if this solution path works for you.

Edit: Note, a few test runs of VLC to export a stream crashes on my Mac. Looks like recent VLC builds support streaming the desktop, which is cool. With soundflower, you can also redirect the system output as well as the mic so that output from the apps and programs are livestreamed as well... provided your copy of VLC is running stably. :)

EDIT:

CamTwist is 32bit. So you will need to download the 32bit version of VLC for Mac OS X:

http://get.videolan.org/vlc/2.0.6/macosx/vlc-2.0.6-intel32.dmg

  1. Fire up CamTwist
  2. Select Desktop (not Desktop+) by double clicking it. This will add it to the list.
  3. Select "Save Setup", and give it a name.
  4. Go to [tools]->[Studio], which will pop up a new window showing a list of "sources", a preview pane, and a program pane. Your new stream probably shows up in "Program", which is the "live webcam" indicator. You can select another source via the buttons and it will show up in the "green preview" window. Hitting "cut" will cut over from preview to program.
  5. Fire up your 32bit VLC
  6. [file]->[open capture device]
  7. Under Capture Device, choose CamTwist.
  8. check the [streaming] radio box
  9. Choose the streaming settings
  10. Choose the [stream] radio button
  11. Leave most of the options as default
  12. Hit OK
  13. Hit Open
  14. This should start the stream.

On my box, my copy of VLC happens to crash at this point, but then again, my version of VLC (2.06 and 2.10) both seem to crash when I try to stream anything. So it might be a problem on my system.

But the above is how I get CamTwist setup and VLC to see CamTwist.

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Were your tests of VLC with recently released version 2.0.6? If not, then which version? –  Graham Perrin Apr 16 '13 at 10:43
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The relatively low cost of this solution is appealing, and the CamTwist Studio 2.0 Basics video is perfectly understandable. However, actually using CamTwist – for the first time – seems far less easy and critically: I don't see how to get output from CamTwist into VLC. Can you work on this answer a little before I decide where to award the bounty? Thanks. –  Graham Perrin Apr 16 '13 at 11:10
    
Updating my answer for CamTwist. For VLC, in order for you to see CamTwist's "webcam", you need to download and run the 32bit version of VLC. The 32/64bit version of VLC would work, but you would need to force it to run in 32bit mode. I downloaded the 32bit version and it was able to see the CamTwist input source. –  Wing Tang Wong Apr 16 '13 at 16:04
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My VLC seems to crash after the streaming starts. Any solutions to this was found? –  pedrofurla Sep 9 '13 at 9:25
    
Have not looked into it further, but can give it a go later today and gt back to you. –  Wing Tang Wong Sep 9 '13 at 22:09
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When I understand correctly you just want to broadcast the Mac's screen.

Maybe Wirecast would be an option: It allows broadcasting a local or remote screen to the a streaming server, such as QT Streaming Server or any flash based like Wowza, Red5,..

Additionally external video sources could be added and mixed at will.

A free alternative would be Flash Media Live Encoder in combination with CamTwist to capture the screen. Here is a tutorial: http://www.mikechambers.com/blog/2011/05/29/setting-up-desktop-streaming-on-mac-os-x/

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Unexpected commitments (moves at work) prevented me from testing this solution before half of the bounty was automatically awarded – sorry! I'll revisit this answer at a later date. –  Graham Perrin Apr 19 '13 at 19:54
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Now worries ;-) I voted up Wing's answer. It sound like a cheap solution. –  TheLostOne Apr 20 '13 at 20:17
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Consider:

SeeVogh Research Network

(You're located in New Zealand. New Zealand Research and Education is a member of the Network.)

With SeeVogh you can broadcast at least:

  • a talking head, if you have a camera and microphone

  • all or part of one screen.

There's a wealth of documentation, much of which relates to EVO (a predecessor to SeeVogh), but the simplest way to realise the features is:

  • register and use the service.

Hints:

  • SeeVogh is more user-friendly than EVO

  • a player for SeeVogh is expected within the next two weeks.

Requirements

On Linux, OS X and Windows:

Locality

Whilst SeeVogh services are non-local, related technologies such as LISA (Large Integrated Services Architecture) should be well-suited to working around bandwidth and other issues (for the curious, there's a MonALISA GUI).


If you find that SeeVogh does not work as expected for users on your LAN, I'll be interested to know; leave a comment.

Postscript: considering the additional information (students aged 5–12), SeeVogh is probably not suitable. I imagine sixteen-year-olds registering for, and using, the software without difficulty; but not five-year olds!

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