Network Services Status

[Rick Stevens]

Thans Susanne,

These are very helpful...and I'm glad to see that we have been making
good progress on the network services prototypes.


Wed, 24 Nov 2004, Susanne Lefvert wrote:

> 
> Here is an update on network services. Feel free to give comments.
> 
> 
> Selector
> =========
> 
> Current State:
> --------------
> Selecting a video stream works well for both Quicktime and VIC.  Selecting 
> audio works for the first stream, however, switching to a new stream 
> causes Quicktime to fail.
> 
> Suggested Improvements:
> -----------------------
> * Recreate timestamps in rtp packages to make audio switching work 
> properly
> * Enable multiple stream selection
> * Separate UI from service and make it run on Windows
> 
> 
> Transcoder:
> ===========
> 
> Current State:
> --------------
> I used rat3 that can transform linear16 8kHz <-> pcmu 8kHz.  An AG venue 
> can, based on client capabilities, connect to the transcoder and send back 
> appropriate streams to the clients.
> 
> Suggested Improvements:
> -----------------------
> * Find/implement a transcoder that is capable of transcoding linear16 
> 16kHz <-> pcmu 8kHz.
> 
> 
> Broadcaster
> ============
> 
> Current State:
> --------------
> When pointed at a venue, the broadcaster retrieves multicast addresses and 
> starts the Selector for video and the Transcoder/Mixer (rat3) for audio.  
> The selected video stream and mixed audio stream are sent to new 
> multicast/unicast addresses.  Next, the broadcaster writes a session 
> description file and starts a web server where the sdp file is published.  
> Quicktime can then be started from a URL and play back audio and display 
> video from the venue.
> 
> Suggested Improvements:
> -----------------------
> * Quicktime can only play back pcmu 8kHz audio.  Find/create a 
> mixer/transcoder that can perform linear16 16kHz -> pcmu 8kHz. (Quicktime 
> fails when using rat3 as a transcoder in linear16 8kHz -> pcmu 8kHz mode)
> * Integrate a QuickBridge so we can send to more than one unicast address.
> * Audio is delayed ~2 seconds compared to video.
> 
> 
> Schemas
> ========
> Prototype xml schemas for node services and nodes can be found at: 
> http://www-unix.mcs.anl.gov/~lefvert/AGEP/AGEP-0128.html
> 
> 
> /Susanne
> 
>