Re: [httpstreaming] Current Status and Our Goal

-----Original Message-----
From: Ali C. Begen (abegen) [mailto:abegen@cisco.com] 
Sent: Wednesday, October 20, 2010 7:22 PM
To: Ning Zong; Roni Even; David A. Bryan; Qin Wu
Cc: httpstreaming@ietf.org
Subject: RE: [httpstreaming] Current Status and Our Goal

When the traffic is unicast, you don't have the problems we have in a
multicast environment. The unicast traffic will naturally start from a
random access point.
[ZN]: I am a little bit confused by the word "naturally". Do you mean the
unicast server will adjust the timing such that the starting packet/segment
will always begin with RAP? In fact, not all the HTTP streaming system
mandates that the segmentation should align with RAP.

 You might need some initialization data to start decoding or whatever, but
all that comes from the server over unicast anyway. 
[ZN]: right, but the reference information is not always available to be
transmitted at any time point even using unicast, unless there is a cache
point.

The same applies to both on-demand and live content. 

-acbegen

> -----Original Message-----
> From: Ning Zong [mailto:zongning@huawei.com]
> Sent: Wednesday, October 20, 2010 11:50 AM
> To: Ali C. Begen (abegen); 'Roni Even'; 'David A. Bryan'; 'Qin Wu'
> Cc: httpstreaming@ietf.org
> Subject: RE: [httpstreaming] Current Status and Our Goal
> 
> IMO, the issue may not only related to multicast or unicast, but the QoE
> improvement (e.g. reduce the startup time after user change the channel).
If
> I remember correctly, in the motivation of FCC in AVT, one important
concern
> is that the Retransmission server can store the most recent GoPs and feed
> them to the client with faster rate than playback to effectively fill the
> gap between the time point of user channel zapping and next complete GoP.
> This improvement also applies to unicast based HTTP streaming, right?
> The above concern also implies that adding some intelligence to
> intermediaries would improve the streaming performance of HTTP streaming
> system. To be more specific, having a deep look at the mechanisms of
> distinguish different types of HTTP traffic (e.g. live streaming with
higher
> timing requirement v.s. normal packet, streaming packet containing I-frame
> worthy of caching for further usage v.s. normal streaming packet) would be
a
> possible direction for consideration in this list.
> 
> My two cents.
> 
> BR,
> Ning Zong
> 
> -----Original Message-----
> From: httpstreaming-bounces@ietf.org
[mailto:httpstreaming-bounces@ietf.org]
> On Behalf Of Ali C. Begen (abegen)
> Sent: Thursday, October 07, 2010 6:15 AM
> To: Roni Even; David A. Bryan; Qin Wu
> Cc: httpstreaming@ietf.org
> Subject: Re: [httpstreaming] Current Status and Our Goal
> 
> > 2. Address the startup issue, we have worked in AVT on fast
> channel/content
> > change and I think this is relevant also in this case.
> 
> Are you assuming a multicast environment for http streaming? Ow, the
startup
> issue is not an issue in unicast connections.
> 
> -acbegen
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