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

["Huangyihong (Rachel)" <[e-mail]>]

Best Regards!
Rachel


-----Original Message-----
From: Glen Zorn [mailto:[e-mail]] 
Sent: Friday, September 21, 2012 2:26 PM
To: Huangyihong (Rachel)
Cc: Glen Zorn; xrblock
Subject: Re: [xrblock] Proposed change to summary discard draft to address discard type issue

On 09/21/2012 12:55 PM, Huangyihong (Rachel) wrote:

...

>
 >
 > In section 3.2.2, the description of Gap Discard Rate field, the
 > third paragraph.
 >
 > 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 filled with number of packets
 > due to both
 >
 > early and late to be played outwhich 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].
 >
 > "
 >
 >
 > I would rewrite this as
 >
 > "where "number of packets discarded" is filled with the number of
 > packets discarded due to both early and late arrivalwhich is obtained
 > from the RTCP XRDiscard Block [DISCARD], and Packets Expected is
 > calculatedas the difference between "extended last sequence number"
 > and "extendedfirst sequence number" (Interval or Cumulative) provided
 > in The Measurement Information block [MEASIDENT]."
 >
 > But even so, it would imply that two instances of the RTCP XR Discard
 > Block are required, since a single Discard block can only report
 > discards due to either early or late arrival, not both. Is that your
 > intent? If so, then I would suggest making it explicit; if not, the
 > maybe just leave the text as it is.
 >
 > [Rachel]: I am okay with your proposed change. Also one instance is
 > sufficient since Discard draft supports reporting discards due to
 > both.

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) which 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].

"

...