RE: webtv-ISSUE-21: Time synchronisation

Hello,

 

I'm told that IEEE-802.1AS is quite good at getting devices to
synchronize to a common timebase (down to the 10's of nS). 

 

UPnP actions to do scheduled playback such as  SyncPlay() (based on the
availability of well synchronized device timebases) were added in AV-4.
This approach is different than the previous approach of having a UPnP
Control Point just send a Play command to the renderer at the "right"
moment.

 

Sorry I couldn't provide the pointers to the specs earlier.

 

Regards,

Russell Berkoff

 

From: public-web-and-tv-request@w3.org
[mailto:public-web-and-tv-request@w3.org] On Behalf Of Jean-Claude
Dufourd
Sent: Monday, June 06, 2011 10:32 AM
To: public-web-and-tv@w3.org
Subject: Re: webtv-ISSUE-21: Time synchronisation

 

I would think the actual relevant section in the second document to be
2.5.9 Clocksync (within the theory of operations you point to in another
email).
All examples point to a synchronisation in seconds. I can believe that
this technology allows a synchronization with a precision of seconds.
We believe there is no way to achieve lip-sync (-20ms to +40ms) with
such a mechanism based on UPnP 1.0, regardless of the media transport
technology used.
Best regards
JC

On 6/6/11 10:47 , Russell Berkoff wrote: 

Hello,

 

The submitted test case is redundant with facilities available in UPnP.

 

UPnP AV-4 provides Linked Content Metadata (Object Linking) as well as
Precision Time Synchronization facilities. As previously mentioned in
this forum, the current UPnP specifications are now available at no
charge.

 

Please refer to:

 

http://www.upnp.org/specs/av/UPnP-av-ContentDirectory-v4-Service.pdf

 

Appendix G: Content Authoring with Object Linking

 

and

 

http://www.upnp.org/specs/av/UPnP-av-AVTransport-v3-Service.pdf

 

2.4.25 SyncPlay()

 

Regards,

Russell Berkoff






-- 
JC Dufourd
Directeur d'Etudes/Professor
Groupe Multimedia/Multimedia Group
Traitement du Signal et Images/Signal and Image Processing
Telecom ParisTech, 37-39 rue Dareau, 75014 Paris, France 
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