Re: [payload] I-D Action: draft-ietf-payload-rtp-ancillary-13.txt

[Thomas Edwards <[e-mail]>]

OK, I am fine with this:

Horizontal_Offset: 12 bits
           This field defines the location of the ANC data packet in an
           SDI raster relative to the start of active video (SAV, a
           digital synchronizing signal present in SDI interfaces) as an
           unsigned integer in network byte order.  A value of 0 means
           that the Ancillary Data Flag (ADF) of the ANC data packet
           begins immediately following SAV.  The horizontal offset
           from SAV is measured in terms of 10-bit words of the
           indicated data stream and data channel.

For line number, I see your point.  Really no point in referencing anything even for SD, how about just:

Line_Number: 11 bits
           This field contains the digital interface line number
           that corresponds to the location of the ANC data
           packet as an unsigned integer in network
           byte order.

-Thomas


On 1/4/18, 4:21 AM, "John Fletcher" <[e-mail]> wrote:

    That is better but there is still the issue that no definition is given for UHD.  I don't think there is any need for make a distinction for SD/HD/UHD, so the last sentence could be as below (deleting the "For SD..." sentence):
    
    "The horizontal offset from SAV is measured in terms of 10-bit words of the indicated data stream/data channel."
    
    I also have a slight issue with the Line_Number definition because it says line number for HD is defined in ITU-R BT.1120 but that does not cover 3G Level A or HFR.  So I would suggest changing the first paragraph to:
    
    "This field contains the line number (as defined in ITU-R BT.1700 [BT1700] for SD video or the appropriate interface mapping specification for HD or UHD video) that corresponds to the location of the ANC data packet in an SDI raster as an unsigned integer in network byte order."
    
    I would also move the paragraph beginning "In multi-stream interfaces ..." so that it follows the first paragraph.
    
    And finally, in the "Note ..." paragraph, I would change "sample structure specification" to "interface mapping specification".
    
    John
    ________________________________________
    From: Thomas Edwards [[e-mail]]
    Sent: 04 January 2018 01:17
    To: John Fletcher; [e-mail]
    Cc: Ali C. Begen
    Subject: Re: [payload] I-D Action: draft-ietf-payload-rtp-ancillary-13.txt
    
    draft-ietf-payload-rtp-ancillary-13 currently says for Horizontal_Offset:
    
    “This field defines the location of the ANC data packet in an SDI raster relative to the start of active video (SAV, a digital synchronizing signal present in SDI interfaces) as an unsigned integer in network byte order.  A value of 0 means that the Ancillary Data Flag (ADF) of the ANC data packet begins immediately following SAV.  For HD, this is in units of Y samples as defined in ITU-R BT.1120 [BT1120]…”
    
    How about we change the last sentence to:
    
    “For HD, the horizontal offset from SAV is measured in terms of 10-bit words of the particular channel indicated by the ‘C’ bit.”
    
    -Thomas
    
    
    On 12/20/17, 9:30 AM, "payload on behalf of John Fletcher" <[e-mail] on behalf of [e-mail]> wrote:
    
        I think there may still be an issue with the definition of Horizontal_Offset.  No definition is given for UHD and I'm not sure that the HD definition in terms of Y samples is always applicable.
    
        The ANC data consists of 10-bit words in a 10-bit data stream (or a data channel of a data stream).  The position should be measured in terms of  10-bit words relative to the SAV sequence in the data stream.  A definition along those lines works regardless of the image format (YCbCr, RGB, 10-bit, 12-bit) or the mapping from source image to interface.
    
        John Fletcher
        ________________________________________
        From: payload [[e-mail]] on behalf of Ali C. Begen [[e-mail]]
        Sent: 16 December 2017 14:21
        To: [e-mail]
        Subject: Re: [payload] I-D Action: draft-ietf-payload-rtp-ancillary-13.txt
    
        Payload WG,
    
        Is there any objection to the latest revision that addresses the issues Thomas pointed out earlier? The draft was in the RFC editor queue and if there are no objections, we will soon ship it back there. But to give people a chance to read and officially comment on the revision, I think we should start a new IETF LC for a week.
    
        @Ben, could we do that?
    
        -acbegen