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Re: webtv-ISSUE-21: Time synchronisation

From: Giuseppe Pascale <giuseppep@opera.com>
Date: Tue, 07 Jun 2011 15:43:27 +0200
To: "Jean-Claude Dufourd" <jean-claude.dufourd@telecom-paristech.fr>, "public-web-and-tv@w3.org" <public-web-and-tv@w3.org>, "Olivier Carmona" <ocarmona@awox.com>
Message-ID: <op.vwpkepw46ugkrk@rabdomant-ubuntu>
On Tue, 07 Jun 2011 10:33:32 +0200, Olivier Carmona <ocarmona@awox.com>  
wrote:

> JC,
>
>
>
> Reversely, an argument such as "let's implement it again" because it  
> does not follow W3C patent policy is not a better way to proceed. Up to  
> my knowledge, there are plenty of technology out on the market that does  
> not follow the W3C Patent Policy such as H.264, AAC, MPEG 4 Visual,  
> etc... for instance and that are referenced by HTML5 (see  
> http://dev.w3.org/html5/spec-author-view/video.html).
>
>
>
> Don't you think that there is a middle way in between here?
>
JC, Olivier, all
my take on this:

I think that, in accordance to out TF charter, what we should try to do is  
the following:
- identify use cases
- identify why these use cases cannot be implemented with current Open  
Standards
- identify existing solution to cover those usecases if already available.

I think there are cases where (for whatever reason) it still make sense to  
"reinvent the wheel" and cases where this doesn't make sense, so the  
discussion needs to be done case by case and I don't think we can set a  
general policy. We can of course give recommendation case by case based on  
different parameters (technical, patents, etc)

At the end, as you know, manufacturer decide what to implement and what  
not, what we can do is to highlight benefit of following a path rather  
than another.

/g

>
>
> Regards,
>
> Olivier
>
>
>
> From: Jean-Claude Dufourd  
> [mailto:jean-claude.dufourd@telecom-paristech.fr]
> Sent: mardi 7 juin 2011 10:19
> To: public-web-and-tv@w3.org
> Subject: Re: webtv-ISSUE-21: Time synchronisation
>
>
>
> Thanks to Russell and Olivier for pointing out the precise technology  
> that allows this type of synchronisation.
>
> However, is this feature present in all discovery and service protocols  
> that HNTF has to consider ? I do not think so.
> So it may be a valid request to have this feature in HNTF, to provide it  
> when the underlying technologies don't.
>
> An argument such as "this feature is already in this standard so do not  
> touch it" is difficult to accept, specially if the standard in question  
> does not follow the W3C patent policy.
>
> Best regards
> JC
>
>
> On 7/6/11 08:05 , Olivier Carmona wrote:
>
> JC,
>
>
>
> As an example, AwoX achieves below +/-10ms using PTP (aka IEEE  
> 1588-2002) within its commercial synchronized solutions above UPnP AV.
>
>
>
> Regards,
>
> Olivier
>
>
>
> From: Russell Berkoff [mailto:r.berkoff@sisa.samsung.com]
> Sent: mardi 7 juin 2011 03:10
> To: Jean-Claude Dufourd;  
> public-web-and-tv@w3.org<mailto:public-web-and-tv@w3.org>
> Subject: 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>  
> [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<mailto: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
> Tel: +33145817733 - Mob: +33677843843 - Fax: +33145817144
>
>
>
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>
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>
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>
> Le message a été vérifié par ESET NOD32 Antivirus.
>
> http://www.eset.com
>
>
>
>
>
>
> --
> 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
> Tel: +33145817733 - Mob: +33677843843 - Fax: +33145817144
>
>
>
> __________ Information provenant d'ESET NOD32 Antivirus, version de la  
> base des signatures de virus 6185 (20110606) __________
>
> Le message a été vérifié par ESET NOD32 Antivirus.
>
> http://www.eset.com
>


-- 
Giuseppe Pascale
TV & Connected Devices
Opera Software - Sweden
Received on Tuesday, 7 June 2011 13:44:00 UTC

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