Internet Engineering Task Force                                 A. Clark
Internet-Draft                                     Telchemy Incorporated
Expires: 30th June 2006                                     A. Pendleton
                                                                  Nortel
                                                            January 2006








             RTCP XR - IP Video Metrics Report Blocks
                  draft-clark-avt-rtcpxr-video-00

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on 30th June 2006.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document defines extensions to the RTCP XR extended report
   packet type blocks to support video over IP (VoIP) monitoring
   for IPTV and video conferencing endpoint reporting.






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Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.   Definitions  . . . . . . . . . . . . . . . . . . . . . . . . 2
   3.   IP Video Metrics Report Block  . . . . . . . . . . . . . . . 4
   4.   IP Video Metrics Configuration Block . . . . . . . . . . . . 9
   5.   Practical applications   . . . . . . . . . . . . . . . . . . 12
   6.   Summary  . . . . . . . . . . . . . . . . . . . . . . . . . . 12
   7.   Security Considerations  . . . . . . . . . . . . . . . . . . 12
   8.   IANA Considerations  . . . . . . . . . . . . . . . . . . . . 12
   9.   Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
   10.  Informative References . . . . . . . . . . . . . . . . . . . 13
        Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 
        Intellectual Property and Copyright Statements . . . . . . . 




1.  Introduction

   This draft defines several new block types to augment those defined
   in RFC3611 for use in Quality of Service reporting for video over IP.  
   The new block types defined in this draft are the IP Video Metrics 
   Report Block, and the IP Video Metrics Configuration Block.


2.  Definitions

   2.1 Local and Remote IP Endpoints

   A report block produced per this draft is normally produced by the
   endpoint of an RTP stream, and relates to the quality of the received
   RTP stream and impairments that may affect the RTP payload. The
   diagram below illustrates the potential end and mid points that may
   be involved in this process.  Within the context of this example, 
   endpoint "C" is the reporting endpoint and the RTCP XR report relates
   to the RTP stream from "B" to "C".  The other points "A", "B" and "D"
   could also be generating RTCP XR reports.


       ----------->    --------RTP---------->   ------------->
   <A>             <B>                       <C>              <D> 
       <-----------    <-------RTP----------- | <-------------
                                              |
                       <------RTCP XR---------|

   With respect to RTCP XR report blocks generated by "C" in relation to
   the RTP stream from "B" to "C".

   (i) The term "External" is used to relate to the network connected to
   the other side of "this" endpoint (i.e. to the connection from "C" to
   "D").

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   (ii) The Local IP Endpoint is "this" endpoint (i.e. "C")

   (iii) The Remote IP Endpoint is the source for the RTP stream
   terminated at this endpoint, and for which packet/frame related
   metrics apply. (i.e. "B")

   (iv) The Remote External Endpoint is the remote endpoint on the
   "external" side of this endpoint (i.e. "D").

   (v) The endpoint on the external side of the Remote IP Endpoint (i.e.
   "A") does not have a specific term applied to it, however note that
   some metrics may apply to the "A" to "B" connection.

   2.2 Cumulative and Interval Metrics

   Cumulative metrics relate to the entire duration of the call to the
   point at which metrics are determined and reported, and are typically
   used to report call quality.  Cumulative metrics generally result in
   a lower volume of data that may need to be stored, as each report
   supersedes earlier reports.

   Interval metrics relate to the period since the last Interval report. 
   Interval data may be easier to correlate with specific network events
   for which timing is known, and may also be used as a basis for
   threshold crossing alerts.
   Note that interval metrics for the start and end of calls may be
   unreliable due to factors such as irregular interval length and the
   difficulty in knowing when packet transmission started and ended.

   2.3 Bursts and Gaps

   The terms Burst and Gap are used in a manner consistent with that of
   RTCP XR (RFC3611).  A Gap is a period of time between Bursts such
   that any lost or discarded packets or frames are separated by some
   number of "good" packets or frames.  A Burst is a period of time that
   fails the test for a Gap, and hence corresponds to a degraded quality
   period.  The recommended value for Gmin in RFC3611 resulted in a
   Burst being a period of time during which the packet loss/discard
   rate exceeded 5%. As video is generally more sensitive to packet loss
   this report block uses a larger value for Gmin.

   2.4 Numeric formats

   This report block makes use of binary fractions.  The terminology
   used is
   
   S X:Y, where S indicates a signed representation, 
                X the number of bits prior to the decimal place and 
                Y the number of bits after the decimal place.

   Hence 8:8 represents an unsigned number in the range 0.0039 to
   255.996.


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3  Video Metrics Report Block

3.1 Block Description

   This block comprises a header and a series of sub-blocks.  The 
   Map field in the header defines which sub-blocks are present.

   Header sub-block
    0               1               2               3
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     BT=N      |           Map                  | block length |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Correlation tag                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Duration                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   IP Layer Loss Metrics sub-block
    0               1               2               3
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Pre-FEC Loss Rate       |   Post-FEC Loss Rate          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 Number of IP packets expected                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   RTP Metrics sub-block
    0               1               2               3
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        SSRC of source                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Loss Rate             |         Discard Rate          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Average Jitter            |    Jitter Percentile          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Threshold     |             Burst Duration (ms)               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Gap Duration (ms)                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Burst Loss/Disc Proportion    |  Gap Loss/Disc Proportion     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  









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   MPEG Transport Metrics sub-block
    0               1               2               3
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Video Stream PID       |      Audio Stream PID         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Loss Rate             |        Discard Rate           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Average Jitter            |    Jitter Percentile          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Threshold     |             Burst Duration (ms)               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Gap Duration (ms)                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Burst Loss/Disc Percentage    |  Gap Loss/Disc Percentage     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Video/Audio Metrics sub-block
    0               1               2               3
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Full Frame Loss Rate       | Interpolated Frame Loss Rate  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   PSNR        |   V Factor    |   VQS Score   |   VCP Score   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Audio MOS-LQ          |          Audio MOS-CQ         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Video bit rate (bits/sec)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Audio bit rate (bits/sec)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    A-V Delay (Network I/F)    |    A-V Delay (Video I/F)      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Round Trip Delay (media)  |   Round Trip Delay (control)  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Playout Buffer Metrics sub-block
    0               1               2               3
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Playout Interrupt Count       | Mean Playout Interrupt Size   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Playout buffer size      |        Mean buffer level      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.2 Header

   Implementations MUST send the Header block within each High
   Resolution Metrics report.

   3.2.1 Block type
   Nine Video Performance Reporting Metrics blocks are defined
		
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   mmm   = Video Metrics- Cumulative, Locally Generated
   mmm+1 = Video Metrics- Cumulative, Relayed from Remote IP Endpoint
   mmm+2 = Video Metrics- Cumulative. Relayed from Remote External
           Endpoint
   mmm+3 = Video Metrics- Interval - Locally Generated
   mmm+4 = Video Metrics- Interval - Relayed from Remote IP Endpoint
   mmm+5 = Video Metrics- Interval - Relayed from Remote External
           Endpoint
   mmm+6 = Video Metrics- Alert - Locally Generated
   mmm+7 = Video Metrics- Alert - Relayed from Remote IP Endpoint
   mmm+8 = Video Metrics- Alert - Relayed from Remote External
           Endpoint

   The time interval associated with these report blocks is left to the
   implementation.  Spacing of RTCP reports should be in accordance
   with RFC3550 however the specific timing of RTCP XR Video reports may
   be determined in response to an internally derived alert such as a
   threshold crossing.

   3.2.2 Map field
   An Map field indicates the optional sub-blocks present in this
   report. A 1 indicates that the sub-block is present, and a 0 that
   the block is absent.  If present, the sub-blocks must be in the 
   sequence defined in this document. 
   The bits have the following definitions:

   0 RTP Metrics block 
   1 MPEG Transport Metrics block
   2-15 Reserved, set to 0

   3.2.3 Block Length
   The block length indicates the length of this report in 32 bit 
   words and includes the header and any extension octets.

   3.2.5 Correlation tag
   The correlation tag facilitates the correlation of this report
   block with other call or session related data or endpoint data.

3.3 IP Layer loss metrics sub-block

   The IP Layer loss metrics sub-block MUST be present.  

   3.3.1 Pre-FEC Loss Rate
   The proportion of IP packets lost before the effects of FEC,
   expressed as a binary fraction in 0:16 format.

   3.3.2 Post-FEC Loss Rate
   The effective proportion of IP packets after before the effects of
   FEC, expressed as a binary fraction in 0:16 format.
   
   3.3.3 Number of IP Packets Expected
   The number of IP packets that the receiving system estimates that
   it should have received.

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3.4 RTP Metrics sub-block

   If RTP transport is used, the RTP Metrics sub-block MUST be present
   and if present MUST be indicated in the Map field.

   3.4.1 Source SSRC
   The SSRC associated with the RTP stream to which this report block
   relates.

   3.4.2 Loss Rate
   The (post-FEC) proportion of RTP frames lost in the network.

   3.4.3 Discard Rate
   The proportion of RTP frames discarded due to late or early 
   arrival.

   3.4.4 Average Jitter
   The average PPDV, MAPDV or Y.1540 jitter level in milliseconds

   3.4.5 Jitter Percentile
   The proportion of RTP frames arriving later than the jitter
   threshold

   3.4.6 Threshold
   The Gmin threshold associated with the definition of bursts and
   gaps.

   3.4.7 Burst duration
   The duration of bursts of lost and discarded RTP frames
   expressed in milliseconds.

   3.4.8 Gap duration
   The mean duration of gaps between bursts expressed in milliseconds.

   3.4.9 Burst loss/discard proportion
   The proportion of frames lost or discarded during burst periods
   expressed as a binary fraction.

   3.4.10 Gap loss/discard proportion
   The proportion of frames lost or discarded during burst periods
   expressed as a binary fraction.

3.5 MPEG Transport Metrics sub-block

   The MPEG Transport Metrics sub-block MUST be present if MPEG 
   Transport is used, and if present MUST be indicated in the Map
   field.

   3.5.1 Video Stream Program ID
   The Program ID (PID) associated with the video stream.

   3.5.2 Audio Stream Program ID
   The Program ID (PID) associated with the audio stream

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   3.5.3 Loss Rate
   The (post-FEC) proportion of Transport Units lost in the network.
   3.5.4 Discard Rate
   The proportion of Transport Units discarded due to late or early 
   arrival.

   3.5.5 Average Jitter
   The average PPDV, MAPDV or Y.1540 jitter level in milliseconds

   3.5.6 Jitter Percentile
   The proportion of Transport Units arriving later than the jitter
   threshold

   3.5.7 Threshold
   The Gmin threshold associated with the definition of bursts and
   gaps.

   3.5.8 Burst duration
   The duration of bursts of lost and discarded Transport Units
   expressed in milliseconds.

   3.5.9 Gap duration
   The mean duration of gaps between bursts expressed in milliseconds.

   3.5.10 Burst loss/discard proportion
   The proportion of Transport Units lost or discarded during burst 
   periods expressed as a binary fraction.

   3.5.11 Gap loss/discard proportion
   The proportion of Transport Units lost or discarded during burst
   periods expressed as a binary fraction.

3.6 Video/Audio Metrics sub-block
   The Video/Audio Metrics sub-block MUST be present.

   3.6.1 Full frame loss rate
   The proportion of full or intra-frame encoded video frames lost

   3.6.2 Interpolated frame loss rate
   The proportion of interpolated video frames lost

   3.6.3 PSNR
   The estimated PSNR in dB

   3.6.4 V Factor
   The video transmission quality expressed as a V Factor

   3.6.5 VQS Score
   The estimated video subjective quality expressed as a VQS score

   3.6.6 Video Control Protocol performance score
   The performance of the video control protocol (tbd)


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   3.6.7 Audio MOS-LQ
   The listening quality of the audio stream expressed as a MOS score.

   3.6.8 Audio MOS-CQ
   The conversational audio quality of an interactive video session

   3.6.9 Video bit rate
   The short term average bit rate of the video codec.

   3.6.10 Audio bit rate
   The short term average bit rate of the audio codec

   3.6.11 Audio-Video Delay (Network Interface)
   The relative delay between audio and video measured before the 
   decoder and expressed in milliseconds

   3.6.12 Audio-Video Delay (Video Interface)
   The relative delay between audio and video measured after the 
   decoder and expressed in milliseconds

   3.6.13 Round Trip Delay (Media)
   The round trip delay for the media path, required only for 
   interactive video sessions.

   3.6.14 Round Trip Delay (Control)
   The round trip delay for the video control (trick play) path.

3.7 Playout Buffer Metrics sub-block
   The Playour Buffer Metrics sub-block MUST be present.

   3.7.1 Playout Interruption Count
   The number of interruptions in video playout that have occurred due
   to playout buffer starvation or excessive packet loss.

   3.7.2 Mean Playout Interruption Size
   The mean size of interruptions in playout, expressed in multiples of
   100 milliseconds

   3.7.3 Playout Buffer Size
   The playout buffer size, expressed in multiples of 100 milliseconds

   3.7.4 Mean Buffer Size
   The average playout buffer size expressed in multiples of 100
   milliseconds

4. RTCP HR Configuration Block

   This block type provides a flexible means to describe the algorithms
   used for call quality calculation and other data.  This block need 
   only be exchanged occasionally, for example sent once at the start 
   of a call.

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   Header sub-block
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     BT=N      |           Map                  | block length |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        SSRC of source                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Correlation tag                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Algorithm sub-block
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Alg type      | Descriptor len|       Algorithm descriptor... |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   ... Algorithm descriptor                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Payload Descriptor sub-block
    0               1               2               3
    0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Video Frame Size (H)    |     Video Frame Size (V)      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Video Frames per Second       |          Configuration        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Video Codec Type            |    Audio Codec Type           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.1 Header

   Implementations MUST send the Header block within each Video Metrics
   Configuration report.

   4.2.1 Block type
   One Video Metrics Configuration block is defined
		
   mmm+9   = Video Metric Configuration Block

   The time interval associated with these report blocks is left to the
   implementation.  Spacing of RTCP reports should be in accordance
   with RFC3550 however the specific timing of RTCP HR reports may
   be determined in response to an internally derived alert such as a
   threshold crossing.

   4.2.2 Map field
   An Map field indicates the optional sub-blocks present in this
   report. A 1 indicates that the sub-block is present, and a 0 that
   the block is absent.  If present, the sub-blocks must be in the 
   sequence defined in this document. 
   The bits have the following definitions:

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   0 Algorithm Descriptor 1 
   1 Algorithm Descriptor 2 
   2 Algorithm Descriptor 3  
   3 Algorithm Descriptor 4 
   4 Algorithm Descriptor 5 
   5 Algorithm Descriptor 6 
   6 Algorithm Descriptor 7 
   7 Algorithm Descriptor 8 
   8 Payload Descriptor 
   9 Vendor Specific Extension
   10-15 Reserved, set to 0

   4.2.3 Block Length
   The block length indicates the length of this report in 32 bit 
   words and includes the header and any extension octets.

   4.2.4 SSRC
   The SSRC of the stream to which this report relates.

   4.2.5 Correlation tag
   The correlation tag facilitates the correlation of this report
   block with other call or session related data or endpoint data.

4.3 Algorithm description

   The Algorithm Description sub-block MAY be present however if present
   MUST be indicated in the MAP field
   The Algorithm descriptor is a bit field which indicates which
   algorithm is being described.  The bits are defined as:-

      Bit 0:      MOS-LQ Algorithm
      Bit 1:      MOS-CQ Algorithm
      Bit 2:      R-LQ Algorithm
      Bit 3:      R-CQ Algorithm
      Bit 4:      Video Monitoring Algorithm
      Bit 5-7:    Reserved and set to 0

  The descriptor length gives the overall length of the descriptor in
  32 bit words and includes the algorithm descriptor and length fields.

  The algorithm descriptor is a text field that contains the
  description or name of the algorithm.  If the algorithm name is 
  shorter than the length of the field then the trailing octets 
  must be set to 0x00.

  For example, an implementation may report:

      Algorithm descriptor = 0x0F   - R and MOS algorithms
      Descriptor length = 3         - 3 words
      Descriptor = "Alg X" 0x00     - description
  



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4.4 Payload description field

   The Extended Payload Description sub-block MAY be present however 
   if present it MUST be indicated in the Header Map field. This sub
   -block provides a detailed description of the payload format used.

   4.3.1 Video Frame Size - Horizontal
   The encoded video frame size expressed in pixels

   4.3.2 Video Frame Size - Vertical
   The encoded video frame size expressed in pixels

   4.3.3 Video Frames per Second
   The number of video frames per second

   4.3.4 Video configuration
   Format TBD but e.g.:-
   - HD
   - Widescreen
   - Audio channels (1, 2, 5.1..)

   4.3.5 Video Codec Type
   Format TBD but - MPEG1,2,4....

   4.3.6 Audio Codec Type
   Format TBD
 
  

5. Practical Applications

5.1 Overview
   The objective of this section is to identify a number of cases in
   which there could potentially be some ambiguity in the application
   of the report blocks defined above or some exceptions to the 
   defined operation of the metrics.  


6. Summary


7. IANA Considerations

8.  Security Considerations

   RTCP reports can contain sensitive information since they can provide
   information about the nature and duration of a session established
   between two endpoints.  As a result, any third party wishing to
   obtain this information should be properly authenticated and the
   information transferred securely.

9.  Contributors


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10.  Informative References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [2]  Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson,
        "RTP: A Transport Protocol for Real-Time Applications", STD 64,
        RFC 3550, July 2003.

   [3]  Friedman, T., Caceres, R. and A. Clark, "RTP Control Protocol
        Extended Reports (RTCP XR)", RFC 3611, November 2003.

Authors' Addresses

   Alan Clark
   Telchemy Incorporated
   3360 Martins Farm Road, Suite 200
   Suwanee, GA  30024
   Email: alan@telchemy.com

   Amy Pendleton
   Nortel
   2380 Performance Drive
   Richardson, TX  75081
   Email: aspen@nortel.com

Full Copyright Statement

   Copyright (C) The Internet Society (2006).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

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   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
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   on the procedures with respect to rights in RFC documents can be
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   Copies of IPR disclosures made to the IETF Secretariat and any
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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



































Clark               Expires June 2006                         [Page 14]