Subject: Re: [AVT] I-D ACTION:draft-ietf-avt-rtp-vc1-00.txt

From: Thomas Kernen <[email-masked]>
Date: Wed, 21 Sep 2005 16:52:26 +0200

[email-masked] wrote:
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Audio/Video Transport Working Group of the IETF.
> 
> 	Title		: RTP Payload Format for Video Codec 1 (VC-1)
> 	Author(s)	: A. Klemets
> 	Filename	: draft-ietf-avt-rtp-vc1-00.txt
> 	Pages		: 21
> 	Date		: 2005-8-25
> 	
>    This memo specifies an RTP payload format for encapsulating Video 
>    Codec 1 (VC-1) compressed bit streams, as defined by the proposed 
>    Society of Motion Picture and Television Engineers (SMPTE) standard, 
>    SMPTE 421M.  SMPTE is the main standardizing body in the motion 
>    imaging industry and the proposed SMPTE 421M standard defines a 
>    compressed video bit stream format and decoding process for 
>    television. 
> 
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-vc1-00.txt
> 

Here are my comments with regards to the draft. These are minor points 
related to wording clarification.

- In section 3, the Advanced profile is referred to as "... making it 
suitable for nearly lossless encoding of HDTV signals". This is subject 
to interpretation and therefore is there a purpose to specify this 
matter? In n years from now the meaning of the term HDTV may not be the 
same as today, therefore this comment may be incorrect. Shouldn't the 
document be more factual?

- In section 3.1, BI-picture is referred to but is not defined in 
section 2. Please could you either define in section 2 or change the 
wording of "These terms are defined in section 2 of this document and in 
section 4.12 of SMPTE 421M [1]". I was expecting to find a reference to 
BI-picture in the section 2 considering it's one liner in 4.12 of SMPTE 
421M.

- In section 4.3, "Knowing if the stream will contain B-pictures helps 
the decoder allocate resources more efficiently, as the encoder will not 
reorder any frames." Should not this be the other way around? "Knowing 
if the stream will NOT contain B-pictures..."

- Across sections 6.1, 6.2 & 8, VC1 is referred to in lowercase and 
uppercase, is this related to the definition of VC1 as an (un)approved 
MIME subtype or simply an overlooked inconsistency in the draft?

HTH
Thomas

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