Re: [payload] WGLC for VP8 Payload

[Jonathan Lennox <[e-mail]>]

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]] On Behalf Of Patrik Westin
Sent: Friday, December 14, 2012 5:47 PM
To: Ali C. Begen (abegen)
Cc: Jonathan Lennox; [e-mail]; [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]>
>>
>>
>>_______________________________________________
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>

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