Subject: [AVT] ABNF in draft-ietf-avt-smpte-rtp-08.txt

From: "Tom-PT Taylor" <[email-masked]>
Date: Wed, 21 Feb 2007 11:21:01 -0500

The ABNF in section 4 of draft-ietf-avt-smpte-rtp-08.txt needs fixing. 
Per RFC 4234, alternatives are expressed by forward slash rather than 
vertical bar. Thus your first line should be:

digit = "0"/"1"/"2"/"3"/"4"/"5"/"6"/"7"/"8"/"9"

I also note a discrepancy (legal, but undesirable) between the complete 
extensionattributes string and its definition as a series of 
space-separated parameters in [hdrext]. Would you consider replacing the 
"/" separator by space as defined in [hdrext]? Or is [hdrext] wrong in 
specifying space as a separator?

Finally, to get what you want for drop, use the square brackets:

drop = "/drop"
or
drop = space "drop"

and

extensionattributes = frame_duration "/" frames_per_tc_second [drop]
or
extensionattributes = frame_duration space frames_per_tc_second [drop]

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: Dave Singer <[email-masked]>
Date: Wed, 21 Feb 2007 10:07:03 -0800

At 11:21  -0500 21/02/07, Tom-PT Taylor wrote:
>The ABNF in section 4 of draft-ietf-avt-smpte-rtp-08.txt needs 
>fixing. Per RFC 4234, alternatives are expressed by forward slash 
>rather than vertical bar. Thus your first line should be:
>

I'm sure I copied this string from another RFC, but I don't mind changing it...

>I also note a discrepancy (legal, but undesirable) between the 
>complete extensionattributes string and its definition as a series 
>of space-separated parameters in [hdrext].

No, hdrext merely says that it is separated from the URI by a space. 
Or did I write something I didn't intend?

>Would you consider replacing the "/" separator by space as defined 
>in [hdrext]? Or is [hdrext] wrong in specifying space as a separator?

as I say, unless I missed something, I don't think it necessary.

>extensionattributes = frame_duration space frames_per_tc_second [drop]

ok

-- 
David Singer
Apple Computer/QuickTime

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From: "Tom-PT Taylor" <[email-masked]>
Date: Wed, 21 Feb 2007 13:36:32 -0500

Look at the first paragraph, last line, of section 7 of [hdrext]. Then 
decide how you want to go -- change [hdrext], change [smpte], or do 
nothing (though as I say, this last is undesirable).

> At 11:21  -0500 21/02/07, Tom-PT Taylor wrote:
...

> as I say, unless I missed something, I don't think it necessary.
...

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From: Dave Singer <[email-masked]>
Date: Wed, 21 Feb 2007 10:41:16 -0800

At 13:36  -0500 21/02/07, Tom-PT Taylor wrote:
>Look at the first paragraph, last line, of section 7 of [hdrext]. 
>Then decide how you want to go -- change [hdrext], change [smpte], 
>or do nothing (though as I say, this last is undesirable).

I'll remove "separated by spaces", thanks.  It's gratuitous.

>>No, hdrext merely says that it is separated from the URI by a 
>>space. Or did I write something I didn't intend?
>>

-- 
David Singer
Apple Computer/QuickTime

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From: Magnus Westerlund <[email-masked]>
Date: Fri, 23 Feb 2007 09:27:49 +0100

Regarding ABNF. There are a lot of different variants to ABNF/BNF. One 
should use only one, and that one is the one documented in RFC 4234. It 
is also highly recommended that one checks the ABNF one has created in 
for example Bill Fenner's online syntax check. It is linked from the 
very useful verification tool webpage:

http://tools.ietf.org/inventory/verif-tools

Cheers

Magnus

-- 

Magnus Westerlund

IETF Transport Area Director & TSVWG Chair
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