1. IEEE P1722 technical issues and talking points
Version 0.01,
Alan K. Bartky
SNAP Networks
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April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

2. Notice of copyright release
This document has been prepared to assist the work of the IEEE P1722 and IEEE 802 Working Groups. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
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The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by the IEEE P1722 Working Group or the IEEE 802 Working Group.
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

3. gm_discontinuity / holdover
Bump count on every discontinuity?
Picked for simplicity and to not have listeners need to have a timeout.
A step in time (no GM changes) does not need to have the talker set the hold
Bump only once until holdover cleared? NO
Either?
holdover
Maximum holdover time?
There is no maximum time for 802.1AS to stabilize.
This is dependency for us
There is a discussion going on in AS
Minimum holdover time?
We don’t believe there is a need to define in 1722
If you step the time, the minimum could be zero.
Holdover time/timeout reset?
Timestamp field use during holdover
802.1BA does not exist and won’t in our timeframe needs. We need to define the minimum accuracy for 802.1AS
100 ppm
Talkers must be GM capable
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

4. Permanent holder over (h bit always 1)
A maximum time for AVBTP in addition to AS maximum time is required
Notes from meeting
AS time
Detection of loss of GM ms
Election of new grandmaster
Wish from 1722 team: Keep max to ms
Must be less than 1 second
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

5. Media clock Reset/discontinuity
Bit to indicate?
Proposal Toggle on change
Consensus this is a useful thing to add
Consensus if there is a toggle, there also must be a minimum time before you can toggle it again.
Tie into holdover bit? No
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

6. IEEE P1722 AVBTP Working Group Contribution
Presentation time
Late presentation time
As normal case, with LP bit
Consensus to drop this bit from the spec
Occasional & permanently late time
Application specific
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

7. IEEE P1722 AVBTP Working Group Contribution
Data smoothing
Multiple packets per 8 kHz tick single stream
Multiple streams (smoothing across streams)
What does and what should 802.1Qav handle?
Qav will handle this and we don’t have to talk about this in 1722
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

8. Mandatory padding of 1722 frame
Should it be required?
No, Alan to change spec to remove this requirement
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

9. IEEE P1722 AVBTP Working Group Contribution
Deprecated types:
Summary of support in AVB
Below is a preliminary list of supported and unsupported parts of the TA Document Audio and Music Data Transmission Protocol 2.1 for P1722 audio end-stations. P1722 Gateways may need to support any format available for maximum compatibility.
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

10. IEEE P1722 AVBTP Working Group Contribution
Deprecated types
These are recommendations for the minimal required support and are based on real world uses of the protocol on IEEE1394 devices. Removal of support for formats like DVD Audio may seem short sighted but DRM restrictions have made use of the format impractical and DVD players use the non-DRM version audio formats instead. The 32bit floating point format is included even though there are no existing implementations using the format because new audio CODECS will support 32bit floating point formatted audio directly and P1722 should be prepared to stream the new format.
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

11. Supported 61883-6 Event Types
8.1 AM824 Data
8.1.2 IEC Conformant Data
8.1.3 Multi-bit Linear Audio (MBLA)
8.1.5 MIDI Conformant Data
Allow mix of the above per rules
bit Floating Point Data
All the above agree to keep
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

12. Deprecated 61883-6 Event Types
AM824 options to be deprecated
8.1.1 Generic Format
8.1.4 One Bit Audio
8.1.6 SMPTE Time Code Data
8.1.7 Sample Count Data
8.1.8 High Precision Multi-bit Linear Audio
8.1.9 Ancillary Data
Application Specific Ancillary Data
bit * 4 Audio Pack
All the above agree to deprecate
Matt to inform 1394TA of our plans to support and deprecate
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

13. IEEE P1722 AVBTP Working Group Contribution
61883 timing
Is current method of “editing instructions” adequate?
Agreed this is an issue, especially for over AVBTP.
Matt to start working on a contribution
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

14. IEEE P1722 AVBTP Working Group Contribution
“Gateway” / “IWU”
Which term to use
Details
Work on Annex B
Agreed single term is needed
Alan to ping Norm on thoughts on a name
Will copy AVBTP team
If no suggestion in 2 weeks, Editor’s discretion on picking new name, then we can re-visit
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

15. IEEE P1722 AVBTP Working Group Contribution
IIDC
Channel mapping
31 on AVBTP
Current IIDC spec specifies only 0 to 15 for valid IDs
Same kind of “edit instructions” as done for series is needed
Additional work for Gateway/IWU for channel mapping
Alan to make fixes based on John’s comments
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution

16. Q tagging and TPID field
MAAP protocol
Question: Should this be best effort instead of priority 6?
This standard will not specify nor recommend.
Will only specify
Protocol MAC address
Protocol Ethertype
Don and Michael to discuss this with Norm at the next 802 AVB meeting
Stream data
Can the bridge strip the TPID and VLAN field on sending to end stations for AVB streams?
April 24, 2017
IEEE P1722 AVBTP Working Group Contribution