Re: [httpstreaming] FW: New Version Notification for draft-zong-httpstreaming-gap-analysis-01

[Thomas Stockhammer <[e-mail]>]

Ning,

thanks ....

I recognized that you only replied to some of my comments.
Does this mean that you agree/disagree with the remaining ones?

Inline some more with [T] ... [\T]

Thomas

> - I am not sure I understand the term "is encrypted into files"
> [ZN]: I mean "use file with media container" here.

[T]  I do not understand this either! [\T]

> - What do you mean "normal text file"?
> [ZN]: traditional web page (e.g. html file).

[T] we should be much more careful with terminology [\T]

> - The intelligence in the Adaptive Streaming over HTTP is almost
> exclusively in the client, there is no negotiation
> [ZN]: Sorry for confusion, "negotiation" should be "massage exchange".

[T]
First I hope this is a typo, otherwise I get more curious ...!
Secondly, I am still not clear what needs to be done beyond regular  
http connections
[\T]

> 5.2)
> - It is not correct that the 3GPP MPD needs to be updated even for
> live. If you use a template mode, the MPD stays static until some
> "unforeseen" event occurs. Client and Content Preparation have agreed
> on rules to construct URIs.
> - If necessary, the MPD update happens asynchronously to the media
> decoding, so this is not considered to be a problem.
> [ZN]: I didn't intend to state that pull model doesn't work. My  
> point is,
> why not investigating the possible usage of push model in certain  
> cases
> without experiencing the above mentioned "unforeseen" event or  
> asynchronous
> updates?

[T]
"Push" is a very very broad term. In Web applications you can for  
example use AJAX or RSS/ATOM like techniques for push-like updates. If  
you use conditional GET for regular polling, this is very efficient.  
The MPD updates in 3GPP work in a similar manner. If you use polling,  
conditional GETs and templates, you are extremely efficient. We should  
really understand what we mean by push model? HTTP-based delivery is  
rich and provides many successfully deployed options.

Should you really refer to something completely different such as IP  
multicast, then I would feel very very uncomfortable.
[\T]

> - There is for sure mechanisms to deliver important packets more
> reliably in HTTP - you just request it earlier. In anticipation of
> switching a smart client may also prepare such data. The client is
> intelligent.
> [ZN]: Well, I think this startup issue doesn't like the pre-fetch  
> which is
> of course still valuable to improve playback. IMO, it is hard to  
> predict
> which channel the user will switch to in the next moment, hence it  
> is not
> reasonable to request important packets for other channels. Did I
> misunderstand you?

[T]
I would not be worried to have the MPD and the initialization segment  
of the two neighboring channels ready in my device. Again, the client  
can be very smart, especially as it does have access to all the  
information.

In general, I do not disagree that we can create more detailed use  
cases for environments in which we envision that HTTP streaming will  
be used. This may include live multi-channel environments. However, we  
should not conclude per se that the existing technologies do have a  
problem.
[\T]

> - 3GPP defines QoE metrics that can reused also for HTTP Streaming.
> there will also be efforts in MPEG in including QoE.
> [ZN]: I am not proposing to focus on defining QoE metrics, but  
> looking on
> the protocols to report such metrics, like RTCP. We will support the  
> work in
> 3GPP/MPEG and cooperate with them to see how to capsulate the  
> metrics in a
> series of messages.

[T]
What do you mean with "capsulate"?
Also, can you be more specific what metrics there are in RTCP that can  
also be used in HTTP Streaming. I consider that anything dealing with  
packet loss is irrelevant. I also do not see the relevance of sending  
regular 5 seconds receiver reports as the content is static and  
adaptation will not happen. Some reporting on Media Presentation level  
may be sufficient, for example when the presentation has been completed.
[\T]


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