[xrblock] Comments on draft-ietf-xrblock-rtcp-xr-synchronization-00

"Claire Bi(jiayu)" <bijy@sttri.com.cn> Thu, 18 October 2012 01:20 UTC

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Date: Thu, 18 Oct 2012 09:19:55 +0800
From: "Claire Bi(jiayu)" <bijy@sttri.com.cn>
To: xrblock <xrblock@ietf.org>
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Subject: [xrblock] Comments on draft-ietf-xrblock-rtcp-xr-synchronization-00
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I was asked to review draft-ietf-xrblock-rtcp-xr-synchronization-00 and have the following several comments.

1. Section 2.1, Synchronization Offset
Is Synchronization Offset a absolute value or relative value? Is Synchronizztion Offset delay variance or Delay Variation?
2. Section 3, last Paragraph said:
   For example,
   one audio stream and one video stream belong to the same session and
   audio stream are transmitted lag behind video stream for multiple
   tens of milliseconds.  The RTP Flows Synchronization Offset block can
   be used to report such synchronization offset between video stream
   and audio stream
Would you like to provide a reference to this example?
3. Section 4.2
s/Statistics Summary Report Block/RTP Flows Initial Synchronization Delay Report Block
4. Section4.2 Definition of Initial Synchronization Delay
It is not clear how to use in-band mapping of RTP and NTP-format timestamps to calculate
the intial Synchronization Delay, it is better to add text to clarify this.