[xrblock] Loss-Type concealment vs Buffer adjustment type concealment

[Qin Wu <[e-mail]>]

Hi,
In draft-ietf-xrblock-rtcp-xr-concsec,concealment is splitted into two type of concealments.
One is Loss-Type concealment and the other is Buffer adjustment type concealment.
So the question is are these two type of concealments applied to video? If the answer is yes,
how to take video loss concealment into account? Since in the current draft, when we define
Loss-type concealment and buffer adjustment type concealment, only audio loss concealment 
is considered. See section 2.2 of draft-ietf-xrblock-rtcp-xr-concsec below for defintions of loss-type concealment
and buffer adjustment type concealment:
"    
     Loss-type concealment is reactive insertion or deletion of samples
      in the audio playout stream due to effective frame loss at the
      audio decoder.  "Effective frame loss" is the event in which a
      frame of coded audio is simply not present at the audio decoder
      when required.  In this case, substitute audio samples are
      generally formed, at the decoder or elsewhere, to reduce audible
      impairment.

      Buffer Adjustment-type concealment is proactive or controlled
      insertion or deletion of samples in the audio playout stream due
      to jitter buffer adaptation, re-sizing or re-centering decisions
      within the endpoint. Because this insertion is controlled, rather than occurring
      randomly in response to losses, it is typically less audible than
      loss-type concealment.  For example, jitter buffer adaptation
      events may be constrained to occur during periods of talker
      silence, in which case only silence duration is affected, or
      sophisticated time-stretching methods for insertion/deletion
      during favorable periods in active speech may be employed.  For
      these reasons, buffer adjustment-type concealment MAY be exempted
      from inclusion in calculations of Concealed Seconds and Severely
      Concealed Seconds.
"

Regards!
-Qin