Re: [payload] WGLC for VP8 Payload

[Glen Zorn <[e-mail]>]

On 12/15/2012 06:27 AM, Stephan Wenger wrote:

> Hi, I'm with Ali here.

Me, too.

> The design choice that has been  made in the VP8 payload is different
 > from the one in the SVC payload, despite similarity in codepoint
 > names and functionality. The reasoning for that ought to be
 > documented. In the SVC payload format, we didn't need to, because we
 > were first in describing something like this :-) A sentence or two
 > should suffice, along the lines Jonathan proposed. Stephan
 >
 > From: "Ali C. Begen (abegen)" <[e-mail]
 > <mailto:[e-mail]>> Date: Friday, 14 December, 2012 15:09 To:
 > "[e-mail] <mailto:[e-mail]>" <[e-mail]
 > <mailto:[e-mail]>>, Jonathan Lennox <[e-mail]
 > <mailto:[e-mail]>> Cc:
 > "[e-mail]
 > <mailto:[e-mail]>"
 > <[e-mail]
 > <mailto:[e-mail]>>, "[e-mail]
 > <mailto:[e-mail]>" <[e-mail]
 > <mailto:[e-mail]>> Subject: Re: [payload] WGLC for VP8
 > Payload
 >
 > Personally (chair-hat off), I think we should. It does not harm
 > anything but provides clarification to someone who is not deep down
 > in every detail.
 >
 > From: Patrik Westin <[e-mail] <mailto:[e-mail]>>
 > Reply-To: "[e-mail] <mailto:[e-mail]>"
 > <[e-mail] <mailto:[e-mail]>> Date: Friday,
 > December 14, 2012 6:06 PM To: Jonathan Lennox <[e-mail]
 > <mailto:[e-mail]>> Cc: "Ali C. Begen" <[e-mail]
 > <mailto:[e-mail]>>, "[e-mail]
 > <mailto:[e-mail]>" <[e-mail]
 > <mailto:[e-mail]>>, "[e-mail]
 > <mailto:[e-mail]>"
 > <[e-mail]
 > <mailto:[e-mail]>> Subject: Re:
 > [payload] WGLC for VP8 Payload
 >
 > Ali do you really want me to add that to the draft?
 >
 >
 > On Fri, Dec 14, 2012 at 2:55 PM, Jonathan Lennox <[e-mail]
 > <mailto:[e-mail]>> wrote:
 >
 > What I think Ali meant was to add some text describing the
 > implications of this design choice for splicers – i.e., if these
 > features are in use, they must re-write packets indefinitely
 > following a splice.
 >
 >
 >
 > *From:*[e-mail] <mailto:[e-mail]>
 > [mailto:[e-mail] <mailto:[e-mail]>] *On Behalf Of
 > *Patrik Westin *Sent:* Friday, December 14, 2012 5:47 PM *To:* Ali C.
 > Begen (abegen) *Cc:* Jonathan Lennox; [e-mail]
 > <mailto:[e-mail]>; [e-mail]
 > <mailto:[e-mail]>
 >
 >
 > *Subject:* Re: [payload] WGLC for VP8 Payload
 >
 >
 >
 > Well he did not have a point in my mind. This is what he wrote.
 >
 >
 >
 > "The VP8 payload format's decision is a reasonable design choice --
 > as compared to the H.264 SVC rules, it removes some ambiguity between
 > splice points and packet loss, giving decoders somewhat greater
 > visibility as to what's going on in the bitstream, and also allows
 > TL0PICIDX and KEYIDX to be orthogonal options because they increment
 > independently."
 >
 >
 >
 > The worst thing that can happen in a draft is to leave ambiguity,
 > which we don't have in the current draft. However if we do it the way
 > H.264 SVC do we could introduce such ambiguity
 >
 >
 >
 > On Fri, Dec 14, 2012 at 2:30 PM, Ali C. Begen (abegen)
 > <[e-mail] <mailto:[e-mail]>> wrote:
 >
 > Are you at least planning to put some text around the point Jonathan
 > brought up?
 >
 >
 >
 > *From: *Patrik Westin <[e-mail]
 > <mailto:[e-mail]>> *Reply-To: *"[e-mail]
 > <mailto:[e-mail]>" <[e-mail]
 > <mailto:[e-mail]>> *Date: *Friday, December 14, 2012 4:53
 > PM
 >
 >
 > *To: *"Ali C. Begen" <[e-mail] <mailto:[e-mail]>>
 >
 > *Cc: *Jonathan Lennox <[e-mail]
 > <mailto:[e-mail]>>, "[e-mail]
 > <mailto:[e-mail]>" <[e-mail]
 > <mailto:[e-mail]>>, "[e-mail]
 > <mailto:[e-mail]>"
 > <[e-mail]
 > <mailto:[e-mail]>>
 >
 >
 > *Subject: *Re: [payload] WGLC for VP8 Payload
 >
 >
 >
 > Trying to send this again since my previous message did not reach the
 > list.
 >
 > Thanks for pointing out the inconsistency. We've submitted a new
 > draft that fixes that problem.
 >
 >
 > The second issue was intentional. We'll keep it this way.
 >
 >
 >
 > On Thu, Dec 13, 2012 at 8:55 AM, Ali C. Begen (abegen)
 > <[e-mail] <mailto:[e-mail]>> wrote:
 >
 > Thanks, the authors just rev'ed the draft to fix the first issue. I
 > hope they will address the second issue first in the list and then
 > reflect the agreement in the next revision. I will hold on to the doc
 > write-up till then.
 >
 >
 > -acbegen
 >
 > -----Original Message----- From: Jonathan Lennox <[e-mail]
 > <mailto:[e-mail]>>
 >
 > Date: Thursday, December 13, 2012 11:29 AM To: "Ali C. Begen"
 > <[e-mail] <mailto:[e-mail]>>, "[e-mail]
 > <mailto:[e-mail]>" <[e-mail]
 > <mailto:[e-mail]>> Cc: "[e-mail]
 > <mailto:[e-mail]>"
 > <[e-mail]
 > <mailto:[e-mail]>>
 >
 > Subject: RE: [payload] WGLC for VP8 Payload
 >
 >> Hi, Ali --
 >>
 >> I just wanted to make sure the issue had been considered; if the
 >> WG agrees that the current design is okay given the limitations
 >> I've mentioned, I'm not going to object.
 >>
 >> Discussion of the issue might be helpful in the document.
 >>
 >> -----Original Message----- From: Ali C. Begen (abegen)
 >> [mailto:[e-mail] <mailto:[e-mail]>] Sent: Tuesday,
 >> December 11, 2012 7:13 PM To: Jonathan Lennox; [e-mail]
 >> <mailto:[e-mail]> Cc: [e-mail]
 >> <mailto:[e-mail]> Subject: Re:
 >> [payload] WGLC for VP8 Payload
 >>
 >> The first one should be fixed by the authors thru a quick revision.
 >> As for the second one, I will ask the authors reply. Also if there
 >> are others who strongly think one way or another, lets discuss it.
 >>
 >> Jonathan, are you ok if the authors simply acknowledge this in the
 >> draft (assuming they agree with you) or do you actually not like
 >> this at all?
 >>
 >> -acbegen
 >>
 >> -----Original Message----- From: Jonathan Lennox
 >> <[e-mail] <mailto:[e-mail]>> Date: Tuesday,
 >> December 11, 2012 11:49 AM To: "[e-mail]
 >> <mailto:[e-mail]>" <[e-mail]
 >> <mailto:[e-mail]>> Subject: Re: [payload] WGLC for VP8
 >> Payload
 >>
 >>> Hi -- I have two comments on this draft. Sorry for being late.
 >>>
 >>> First of all, an editorial matter: Section 6 says the format has
 >>> no parameters, but section 6.1 lists two optional parameters
 >>> (max-fr and max-fs).
 >>>
 >>>
 >>> Secondly, more substantively, I note that the payload format's
 >>> rules on KEYIDX and TL0PICIDX impose a fair bit of overhead on
 >>> boxes that wish to splice together VP8 streams, since both values
 >>> are required to always increment consecutively in a bitstream (if
 >>> they're being used).
 >>>
 >>> By contrast, the equivalent fields of the H.264 SVC payload
 >>> format (in the PACSI) just say that IDRPICID must be different in
 >>> consecutive IDR frames, without requiring that the value
 >>> increment by 1; and TL0PICIDX resets to 0 on every IDR frame,
 >>> rather than carrying on continuously. (H.264's IDR frames are
 >>> analogous for these purposes to VP8's essential keyframes).
 >>>
 >>> This means that an H.264 SVC splicer -- as long as it doesn't
 >>> get unlucky, such that the two streams it's splicing happen to
 >>> have identical IDRPICID values at the splice point -- can just
 >>> transition from one bitstream to another at any IDR frame.
 >>>
 >>> By contrast, following a splice, a VP8 splicer must re-write both
 >>> these fields for the rest of the lifetime of the stream, since
 >>> they each have only one valid possible value following the
 >>> splice.
 >>>
 >>> The VP8 payload format's decision is a reasonable design choice
 >>> -- as compared to the H.264 SVC rules, it removes some ambiguity
 >>> between splice points and packet loss, giving decoders somewhat
 >>> greater visibility as to what's going on in the bitstream, and
 >>> also allows TL0PICIDX and KEYIDX to be orthogonal options because
 >>> they increment independently. However, I wanted to make sure
 >>> this had been considered explicitly by the working group, and we
 >>> had consensus that it was the right decision.
 >>>
 >>> (Note well disclaimer: Vidyo has an IPR declaration against the
 >>> VP8 payload -- see <http://tracker.tools.ietf.org/ipr/1622/>.)
 >>>
 >>>
 >>> On Dec 5, 2012, at 9:20 PM, Ali C. Begen (abegen) wrote:
 >>>
 >>>> I have not seen any comments on the list. Please review the
 >>>> draft and post your comments on the list.
 >>>>
 >>>> Thanks. -acbegen
 >>>>
 >>>> -----Original Message----- From: "Ali C. Begen"
 >>>> <[e-mail] <mailto:[e-mail]>> Date: Monday,
 >>>> November 19, 2012 3:15 PM To: "[e-mail]
 >>>> <mailto:[e-mail]>" <[e-mail]
 >>>> <mailto:[e-mail]>> Subject: [payload] WGLC for VP8
 >>>> Payload
 >>>>
 >>>>> Hi everyone,
 >>>>>
 >>>>> We had a WGLC for this draft earlier this year and there have
 >>>>> been a few updates to the document. I am starting a 2nd
 >>>>> WGLC. Please review and comment on the list by December
 >>>>> 10th.
 >>>>>
 >>>>> https://datatracker.ietf.org/doc/draft-ietf-payload-vp8/?include_tex
 >
 >>>>>
 >>>> t=1
 >>>>>
 >>>> https://www.ietf.org/mailman/listinfo/payload
 >>>>
 >>>
 >>> -- Jonathan Lennox [e-mail]
 >>> <mailto:[e-mail]>
 >>>
 >>>
 >>> _______________________________________________ payload mailing
 >>> list [e-mail] <mailto:[e-mail]>
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 >>
 >
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