[AG-TECH] Recording and streaming access grid session using Windows Media Encoder or VLC

[Andrew Rowley]

Hi,

 

Just to say that I have also been looking at these issues in relation to Memetic - in the CREW project, we have created a system for generating FLV files from recorded AG streams and this then allows you to show them from within a flash player.  I am now applying for funding to formalise this into a web service and have it generate other formats too.  This could then be extended to work with live streams fairly easily.  If the project gets funded, I will be setting up a Google Code site for it so others will be able to contribute and extend or reuse the code.  I would be happy for this to happen - I will keep you informed about any developments (this would start in April if successful).

 

One thing to note is that it doesn't combine streams into a single FLV just now (although this could come out of the project).  In CREW, we just select two of the streams (the speaker and the presentation slides) and synchronize those as separate streams in the CREW player.  You can look at this at http://crew.rcs.manchester.ac.uk/ - note that this is a demo site, and we don't know what it is like under high loads so it might not respond if too many people are trying at the same time!

 

One thing to think about with the live streaming is the fact that you only need to encode the streams once.  This could then be sent out to as many people as there are listening - this scales better than encoding once per user.  With a good flash player implementation, you could also support pause and rewind, although it is worth noting that flash can only jump to key frames, and increasing the number of key frames increases the bandwidth required to watch it.  There would need to be a trade off calculation in there somewhere.

 

Andrew :-)

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  Andrew G D Rowley
  Senior Development Officer

  Research Computing Services
  The University of Manchester
  Devonshire House, Oxford Road
  Manchester, M13 9PL

  t :  +44 (0) 161 275 0685
  e :  Andrew.Rowley at manchester.ac.uk
  w :  www.manchester.ac.uk/researchcomputing

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________________________________

From: ag-tech-bounces at lists.mcs.anl.gov [mailto:ag-tech-bounces at lists.mcs.anl.gov] On Behalf Of Andrew Ford
Sent: 04 February 2009 20:19
To: Thomas D. Uram
Cc: ag-tech at mcs.anl.gov
Subject: Re: [AG-TECH] Recording and streaming access grid session using Windows Media Encoder or VLC

 

Hi Tom,

Just FYI, I can't seem to compile AGVCRToMPEG2, and there are some other reasons this won't compile out of the box for most other people:

1) it won't compile on g++ 4.3 - there are a number of instances of <string.h> and other c libraries that need to be changed to <cstring>, etc
2) the script for compiling AGVCRToMPEG2.cpp won't find avformat.h, as it has -I/path/to/ffmpeg/libavformat and a few other subdirectories whereas a recent version of libavformat (svn20080206) seems to put them straight in /usr/include/ffmpeg

After fixing all that I get the error:
VPCMPEG2TSConsumer.cpp:73: error: cannot convert 'ByteIOContext**' to 'ByteIOContext*' for argument '1' to 'int url_fclose(ByteIOContext*)'

I'm not sure if this is g++ 4.3 being specifically finicky about pointer casting or what - I haven't had much time to actually dive into this code and see if there's a way around it. Any ideas?

Also, in the future I'd definitely be interested in expanding this to be more comprehensive - adding h264 decoding support is up there, plus I'd like to see if it's possible to make something out of this that would decode and tile/aggregate all videos from a venue in realtime to throw it somewhere else for streaming purposes.

--Andrew

2009/2/3 Thomas D. Uram <turam at mcs.anl.gov>

I'd like to point out that the V* code from ANU includes the AGVCRToMPEG2 project. All of this code, which was previously on agcentral.org, is now available in the UChicago subversion repository here:

    https://www.ci.uchicago.edu/svn/if-media

I've had mixed success with AGVCRToMPEG2 so far. With some work, it could be the missing link for recording and playback of AG sessions in standard movie formats.

If you're interested in this code and end up making changes that you'd like to contribute back, you'd simply need to get a UChicago account.  I'll send separate mail to the list with more details soon.

Tom




On 2/3/09 1:35 PM, Tran, Quang V. wrote: 

Thanks Todd.  We are looking to live webstreaming to users desktops.  Look like splitting video/audio feeds is the better option for us.

 

--

 

Quang Tran

LSU Health Sciences Center

qtran3 at lsuhsc.edu

 

________________________________

From: Todd Zimmerman [mailto:todd.zimmerman at ubc.ca]
Sent: Tue 2/3/2009 1:26 PM
To: Tran, Quang V.
Cc: ag-tech at mcs.anl.gov
Subject: Re: [AG-TECH] Recording and streaming access grid session using Windows Media Encoder or VLC

On Mon, 2009-02-02 at 15:46 -0600, Tran, Quang V. wrote:
> 
> Is it possible to use Windows Media Encoder or VLC to capture and
> stream an access grid session?  If not, is there another way to do
> this?

Are you looking to webstream it to browser/clients?  Or record /
rebroadcast via AG?

As Jeremy mentioned, agvcr will record and rebroadcast the AG event, but
will still only be available for AG style clients.

Webstreaming is a bit more difficult since AG is made up of multiple
video feeds etc.  If there is a specific 'presenting' site, then we use
a separate capture box (with a split of the primary camera feed and a
separate 'mixed' audio feed from all the sits) - then used VLC to send
it to a Quicktime/Darwin streaming server.  VLC will also concurrently
record the single video/mixed(all sites) audio for a webstream archive.



Cheers,

Todd






 

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