Subject: European contribution

From: [email-masked] (David Tarrant)
Date: Fri, 4 Dec 1998 15:53:15 +0000

submit [email-masked]

Hello,

I will be attending the "IP over the VBI" session at next week's IETF meeting 
on behalf of the European Association of Consumer Electronics Manufacturers 
(EACEM). I will be willing to present the official EACEM (= European) 
position on the use of 625 line WST for data broadcasting.  The attached 
document contains the updates that we will be making to the existing European 
standard (ETSI document number ETS 300 708) which deals with data 
broadcasting in 625 line analogue TV systems. The changes improve the ability 
of WST to carry services such as "IP over the VBI". The document describes 
the format of a new independent packet and an FEC. 

There remains the task of mapping the new packet type to the "IP over the 
VBI" spec. The application has to define the use of the APP1 and APP0 bits in 
the Format Type byte. We propose that APP0 indicates whether the User Data 
field is full of useful data (= 0), or some or all of the User Data is filler 
data (=1). The codes for filler data, framing and IP compression remain the 
same as for the 525 line proposals.

We do not have a use for APP1 at present. The NABTS version takes two bits to 
indicate the length of the suffix on the data block, but the CI value already 
implies this (0-13 = 2 suffix bytes per packet; 14-15 = 37).

I look forward to next week's meeting. 

Kind regards,

David Tarrant
__________________________________________________________________________ 
Philips Semiconductors Systems Laboratory,        Tel: +44 (0) 1703 316376 
Millbrook Industrial Estate,                      Fax: +44 (0) 1703 316304 
Southampton, SO15 0DJ, UK.       Email: [email-masked]

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From: "Victor Papanaoum" <[email-masked]>
Date: Mon, 7 Dec 1998 11:18:26 +0800

Hello David

I have a suggestion regarding the Data Channel allocation scheme 
proposed by EACAM in the document Teletext IDL - Format B.

Currently, the document proposes to assign Data Channel number 
15 to IDL Format B (section 3).  Since the document already 
proposes to use the Format Type to distinguish between IDL 
Format A and IDL Format B, it would appear to make more sense 
for Format B to use the same Data Channel numbers already 
allocated to Format A.  In other words Data Channels 8 through to 
11 are used for both Format A and Format B.  This allocation 
scheme means that more Data Channels are available for Format 
B, keeps the Data Channel numbering scheme in ETSI 300 708 
unchanged and leaves the other Data Channels, including Data 
Channel 15, free for future standardisation.  

Please note the EACAM document already implies that this type of 
Data Channel allocation scheme should be used (para. 3, section 
2.1).

Regards

Victor Papanaoum
Io Research