Re: [xrblock] Proposed change to summary discard draft to address discard type issue

[Qin Wu <[e-mail]>]

Hi,
----- Original Message ----- 
From: "Glen Zorn" <[e-mail]>
To: "Qin Wu" <[e-mail]>
Cc: "Huangyihong (Rachel)" <[e-mail]>; "Glen Zorn" <[e-mail]>; "xrblock" <[e-mail]>
Sent: Friday, September 21, 2012 4:31 PM
Subject: Re: [xrblock] Proposed change to summary discard draft to address discard type issue


> On 09/21/2012 02:36 PM, Qin Wu wrote:
> 
> ...
> 
>>
> > Yes but the statement that the '"number of packets discarded" is
> > filled with the number of packets discarded due to both early and
> > late arrival which is obtained from the RTCP XR Discard Block" is
> > only true if a) the "Discard Type" field in the Discard block is set
> > to 11 or b) two instances of the Discard block are present, one with
> > the DT field set to 10 & the other with the DT field set to 01. Do
> > you think that that should be mentioned?
> >
> > [Rachel]: I got your point. How about changing the text to : " where
> > "number of packets discarded" is filled with the number of packets
> > discarded due to both early and late arrival (e.g. the discard type
> > field in the Discard block is set to 11)
> >
> > [Qin]: say "e.g." is not correct, it is better to rephrase as
> > (i.e.,Discard Type (DT) field set to 11 in the Discard block)
> 
> Yes, "e.g." is not right, but because it appears that this data is only 
> valid under certain conditions, I think that it would be better to spell 
> out those conditions precisely.

[Qin] I think calculate "number of packets discards" based on two instances of Discard Block is
not more straightforward than filling "number of packets discards" with the the number of packet 
discarded due to both early arrival and late arrival (DT=3) since you need to do the sum. But discard (DT=3)block may be not 
received in some case. So how about add the following text at the end of section 3.2.2:
OLD TEXT:
"
where "number of packets discarded" is obtained from the RTCP XR Discard Block [DISCARD] and 
Packets Expected is calculated as the difference between "extended last sequence number"
and "extended first sequence number" (Interval or Cumulative) provided in the
Measurement Information block [MEASIDENT].
"
NEW TEXT:
"
where "number of packets discarded" is obtained from the RTCP XR Discard Count Block [DISCARD] and 
Packets Expected is calculated as the difference between "extended last sequence number" 
and "extended first sequence number" (Interval or Cumulative) provided in the
Measurement Information block [MEASIDENT]. If Discard Count (DT=3) Block is received, 
"the number of packet discarded"is filled with the number of packets discarded due to both early 
and late arrival(DT=3). If Discard Count (DT=3) is not received, "the number of packet discarded"
 is calculated as the sum of packet discards due to early arrival (DT=1)and packet discards due to late arrival(DT=2).
"
Is that what you are looking for? Or you have other proposal?
> ...
>